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Humans among the primates

The views expressed are those of the author and are not necessarily those of Scientific American.

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A montage of modern primates. From left to right: human, tarsier, gorilla, bonobo, orangutan, crested gibbon, capuchin, macaque, lemur. Image by Darren Naish.

It is not in the least bit controversial to picture humans* within the context of the placental mammal group that we belong to, the primates. Nor is it unusual for primatologists, anthropologists or biologists of other sorts to compare the anatomy, social or sexual behaviour, lifestyles or cognitive abilities of humans with those of other primates (e.g., Morris 1967, Sarmiento 1995, 1998, de Waal 2002). Despite this, Homo sapiens is often missed out or ignored when authors review the living primates of the world**, a perhaps understandable omission given that these works are about ‘other’ animals, but a misleading one given that it really helps to see the human lineage as part of the group; as an important and conspicuous part of primate diversity.

It is neither novel nor innovative to compare humans with other primates. Here's the cover of a famous book that aimed to popularise a scenario of human evolution and biology.

* ‘Human’ as used throughout this article denotes Homo sapiens alone. When H. sapiens and its extinct relatives are being referred to, the term ‘hominin’ is used.

** I should note that several books that cover primate diversity do include our species within the roster: Walker’s Mammals of the World does, so does Redmond’s The Primate Family Tree and Dunbar and Barrett’s Cousins: Our Primate Relatives, for example.

In many respects, Homo sapiens is an ‘extreme’ primate. Our vocal abilities, cultural diversity and application of technology (this includes the use of fire) exceeds that of other primates, and it can be argued that it is unparalleled technological innovation that has enabled us to pursue lifestyles – those involving agriculture, livestock management, or regular travel at sea, for example – that are so different relative to those of other primate species. In many respects, however, we aren’t unusual at all and fit within the broad spectrum of primate diversity: our substantial anatomical and cultural diversity is what we would predict for a widespread primate that occurs in numerous habitats, many of the anatomical and behavioural traits once considered unique to humans are not unique at all, and our social systems fit within the spectrum present in related primate species. [Images below by Tropenmuseum of the Royal Tropical Institute and Agência Brasil.]

Technological innovation, the exploitation of other animals, and complex systems of planning, co-operation and management of territories have allowed humans to follow lifestyles not allowed to other primates. Clockwise from top left: complex land management, agriculture and the manipulation of plants; the crossing of water via boats and ships; the domestication and use of other animals, like these cattle; reliance on aquatic resources that are harvested with nets and other inventions. Clockwise from top left: Philippines rice terraces by unknown photographer ( licensed under Creative Commons Attribution 2.5 Generic license); 1912-13 photo of Papuan people on Lorentz River by August Adriaan (licensed under Creative Commons Attribution 3.0 Brazil license); traffic scene in Mumbai by Antônio Milena/ABr. (licensed under Creative Commons Attribution 3.0 Brazil license); Mexican fisherman image by Régis Lachaume (in public domain).

In the following text, I want to explore just a few ideas that arise when we compare ourselves to our close relatives. The more we learn about primate biology, history and evolution, the smaller the gaps become between Homo sapiens and other primate species, and the less unusual we appear. Indeed, most of our traditional ideas about human ‘uniqueness’ reflect the fact that the species that seemingly bridge the gap between us and our closest living relatives are extinct.

Adrienne Zihlman and colleagues argued that Bonobos (Pan paniscus) represent a good morphological match for the African ape concestor: this diagram (from Zihlman 1984) combines Bonobo anatomy on the left with that of an australopithecine on the right.

Little discussed today is the fact that humans are unusual apes in that we’re actually proportioned more like monkeys. In fact, our superficially ‘monkey-like’ anatomy goes some way to explaining why the idea of a ‘pre-pongid’ divergence of the human lineage was so popular among anatomists prior to the molecular age (see Bowler 1987, Sarmiento 1998). The idea that living (non-human) apes are all somewhat specialised and thus different from whichever species were ancestral to the human lineage has often been mentioned, and as more fossil apes have been discovered it has become clear that hominids and hominid-like hominoids possessed a diversity of body plans, some of which were more ‘monkey-like’ than ‘ape-like’ (e.g., Moyà-Solà et al. 2004).

However, fossils show that hominins evolved from among a radiation of species with ‘ape-like’ proportions; the idea that the common ancestor of the whole African ape clade was Bonobo-like overall has been proposed (Zihlman et al. 1978), and data from australopithecines shows that some, at least, had ‘ape-like’ long forelimbs and proportionally short hindlimbs, though they didn’t have the same skeletal specialisations for climbing or knuckle-walking as extant African apes (McHenry & Berger 1998, Lovejoy et al. 2009, Berger 2013). The evolution of especially long hindlimbs and of forelimbs proportioned more like those of monkeys than apes are therefore hominin innovations evolved somewhere on the branch between certain australopithecine species and the earliest members of Homo.

Let’s get it out of the way: apes are monkeys

If humans are apes, apes are monkeys. Image by Darren Naish, and available on a t-shirt...

Having mentioned monkeys, there’s something we have to get out of the way. The idea that humans are apes is a familiar and generally accepted one among people who follow tree-based thinking. Furthermore, despite the traditional idea that humans are ‘different enough’ from other primates to warrant their own group, we recognise today that Homo, Australopithecus and their close relatives should be united with chimps, gorillas and other great apes in a group that shares a single common ancestor. This group is Hominidae, within which the African ape branch is termed Homininae (the hominines), within which the human branch is termed Hominini (the hominins). Together with their ‘lesser ape’ relatives the gibbons and siamangs (the hylobatids), hominids are part of a more include clade called Hominoidea.

So, humans are apes from the phylogenetic point of view. That is, in scientific parlance, ‘ape’ no longer means ‘non-human hominoid’ (you might argue that, in common parlance, ‘ape’ does indeed mean ‘non-human hominoid’, but common parlance does not dictate best practice). But, if humans are apes it’s time to bite the bullet and admit that humans, and apes as a whole, are also monkeys. Again, common parlance would have it that monkeys are small, typically tailed, and do not include apes but, from a tree-based, phylogenetic point of view, apes are a particular group of large, tailless monkeys.

Like many people, I long resisted vociferously to this idea, insisting that the term ‘monkey’ has to be restricted to non-ape anthropoids (Anthropoidea is the clade that includes New World monkeys and both Old World monkeys and apes). But if birds are dinosaurs, whales are artiodactyls, and humans are apes then, dammit, apes are monkeys. This video from the brilliant AronRa helped sway my opinion, and you can help preach the message with this new t-shirt I’ve recently designed!

Apparently this colour is called 'lemon'. I will be wearing mine on the conference circuit this year. Oh, I'm not doing the conference circuit this year... oh well.

Bipedality, orthogrady, hips and hindlimbs

Orangutans and gibbons are capable of proficient bipedality and often use it in terrestrial settings and on compliant branches. This could mean that bipedality originally evolved in an arboreal setting. Image by Darren Naish.

Let’s now look at various anatomical features of humans and see how they compare to those of other primates. For no particular reason we begin with habitual bipedal behaviour, something that occurs more regularly in some non-human primates than used to be thought, a fact that has only become better appreciated as more hours of field observation have been logged, as more species have been intensively studied, and as improved technology has allowed people to better record behaviour. There are several competing ideas on the distribution and early evolution of orthograde (= erect-bodied) bipedalism, with the idea that bipedality evolved in a terrestrial setting from quadrupedal, pronograde (= horizontal-bodied), knuckle-walking ancestors still being supported by some lines of evidence (e.g., Richmond & Strait 2000, Richmond et al. 2001).

Lumbar vertebra of the Miocene hominoid Morotopithecus bishopi (with C being a CT-scan of a human lumbar vertebra) showing the similar form and position of the Morotopithecus transverse process and associated structures relative to those of humans. Image by Aaron G. Filler, licensed under Creative Commons Attribution-Share Alike 2.5 Generic license.

However, the presence of both arboreal and terrestrial bipedal behaviour in gibbons and orangutans (Stanford 2006, Thorpe et al. 2006, 2007, b) and the presence of features associated with bipedal behaviour in fossil hominoids like Morotopithecus and Orrorin suggests that proficient bipedal abilities were present in some of the earliest hominids and hence inherited by hominines (the African ape clade) and hominins (australopithecines and Homo). Under this scenario, bipedalism evolved in an arboreal setting, and quadrupedal hominines (gorillas and chimps) evolved from more bipedal ancestors, knuckle walking evolving independently at least twice (see Dainton & Macho 1999).

Note that all of the skeletal features associated with bipedalism in humans – all of them – are present in various non-humans where they also assist in bipedal behaviours, or are associated with vertical climbing or quadrupedality (Sarmiento & Marcus 2000). We thus see such features as short hips, a prominent ischial spine, a wide sacrum, and a femur with a strong bicondylar angle in such taxa as spider monkeys, howler monkeys, orangutans and lorises (Sarmiento & Marcus 2000): the characters concerned are not unique to humans; rather, humans are unique in combining this diverse set of features.

A very special pelt

Ultra-fine, ultra-tiny hair on a Caucasian human (here, on the upper and inner part of the left forearm).

Humans appear somewhat weird in possessing several features that look unusual compared to those of other primates. Perhaps the most famous aspect of human weirdness concerns our super-fine, especially short body hairs; our pelage is so fine that it creates the impression of a naked-skinned appearance. As has been argued several times, humans are not ‘naked’ at all: according to Schwartz & Rosenblum (1981) our hair follicles are distributed at the sort of density expected for an ape of our size.

Exactly what sort of selection led to our reduced pelt has been the source of substantial speculation (and virtually all of it really is just speculation): is it a product of neoteny (Morris 1967), were thermoregulatory pressures paramount (Wheeler 1992), was it to reduce parasite loads (Pagel & Bodmer 2003), or was it something to do with sexual selection (Darwin 1888) or, most radically, adaptation to an amphibious mode of life (Morgan 1997)? Based on the ecological context in which we evolved (tropical woodland-savannah complexes with watercourses and coasts within walking distance) and the presence within our species of sexually dimorphic integumentary features (read on), a combination of sexual selection and thermoregulation seems most likely.

Human body hair is highly variable across the peoples of different regions. Diagram by Undress 006, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

The human face and nose

Cranial peculiarities of Homo sapiens: long head hair, the nose, white sclera to the eyes, eyebrows.

Other anatomical peculiarities include our hemispherical buttocks and our especially robust, fully adducted hallux (‘big toe’) (‘adducted’ means that it’s been moved to occupy a position close to the midline of the foot: the opposite anatomical term – referring to a position away from the midline – is ‘abducted’).

And yet more weirdness comes from the fact that we are flamboyant animals, our bodies acting as billboards that advertise sexual condition and quality, and our faces possessing features that function in visual display and social behaviour: eyebrows, the white sclera and sometimes blue, grey, green or hazel irides of our eyes, the beards and moustaches of males (in some, not all, populations) and long head hair.

Seen within the context of facial characters present across primates (not in apes alone), none of our facial features are remarkable: pale or unusually coloured eyes, beards and moustaches, pale and dark streaks, bars and circles around and above the eyes, and showy masses of head hair are present across monkeys and apes. The prominent, cartilage-supported, ‘hooded’ human nose looks unusual compared to that of other extant apes and presumably evolved as an aid to thermoregulation, filtration and water control (Elad et al. 1993, Churchill et al. 2004), crucial within the environments we evolved in: its evolution is ‘logical’ in a big-bodied, erect mammal that walks long distances in arid or semi-arid environments.

The human nose is highly variable in size and shape. Remarkable crooked shapes as shown here are seen in many people of European ancestry. Image by unknown photographer, licensed under Creative Commons Attribution-Share Alike 2.0 Generic license.

Our large nose – involving innovations in the form and size of the nasal, ethmoid, sphenoid and maxilla and position of the fleshy nostril openings – can thus be seen as the best solution a short-faced primate could make in adapting to these problems, a poor version of the enhanced noses present in other big mammals of similar environments, but one which occurred in step with pharyngeal shape and hence vocal communication. In the simple sense of what it looks like on the outside, the human nose is, again, not unique within primates but has precedent in the pendulous noses of some cercopithecid monkeys where hooded and pendulous noses almost certainly evolved within the regime of sexual display. While the human face undeniably reflects a complex evolutionary interplay between social signalling, environmental, dietary adaptation and our short-faced, big-brained anthropoid legacy, the general message behind its anatomy is that we are part of the spectrum of elaborate facial forms present across our group.

The human female

A randomly selected image of a group of women. These are Fula women of Paoua, Central African Republic. The Fula number over 40 million, speak Fulfulde, and include a significant nomadic component: they are one of the most diverse and important groups of African people. Image by hdptcar, licensed under Creative Commons Attribution 2.0 Generic license.

It sometimes seems assumed that the features of the human female body associated with sexuality are ‘unusual’ compared to the anatomy of non-human primates. The fact that signs of oestrus are ‘concealed’ by the human body (we don’t produce obvious sexual swellings) has been much discussed and usually taken as evidence that the evolution of our anatomy was driven by the maintenance of pair-bonds, and hence social cohesion, through sex (Lovejoy 1981). Some authors have argued that oestrus shouldn’t be considered ‘concealed’, but – rather – that human females display what looks like ‘permanent oestrus’ (Szalay & Costello 1991). [Photo above by hdptcar.]

Pectoral display structures are present in geladas (both males and females). This is a female. Image by BluesyPete, licensed under Creative Commons Attribution-Share Alike 3.0 Unported, 2.5 Generic, 2.0 Generic and 1.0 Generic license.

Human breasts are not unprecedented when we look at the pectoral display structures of other primates (Geladas Theropithecus gelada, with their brightly coloured array of intermittently-present pink pectoral vesicles, are the classic example [adjacent photo by BluesyPete]), and those of average individuals don’t seem tremendously unusual in size or proportions compared to those of other hominids during parts of their reproductive cycles. Having said that, I don’t think there’s any indication that the breasts of bonobos, gorillas or orangutans play the same role in sexual attraction as they do in humans, and human breasts typically contain more fatty tissue that those of other primates. Most hypotheses put forward to explain the evolution of breasts posit that they are honest indicators of fat reserves and hence advertise reproductive potential in some way. Marlowe (1997) termed this the Nubility Hypothesis. The idea that they might deceive potential partners by enhancing perceived reproductive potential – the so-called Deception Hypothesis (Caro & Sellen 1989) – has also been put forward. [Woman of Willendorf image below by Matthias Kabel.]

The Woman (or "Venus") of Willendorf, a c. 25,000 year old human figurine discovered in Austria in 1908. Whatever figures like this were 'for' (if anything), they help illustrate the symbolic significance of breasts within our species. Image by Matthias Kabel, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

The inevitable conclusion of this line of argumentation is that female bodies display a permanent sexual availability that evolved in step with bipedality, that the evolution of breasts and other female secondary sexual characteristics was adaptive as it enhanced access to resources acquired by males and acted as an anti-infanticidal strategy (because males would assume that children were the products of the numerous matings they had had with their ‘permanently available’ partners), and that it links to our reduced pelage (by making females, and sex, ‘sexier’).

However, there are several reasons why this view of humans as creatures that display a mock ‘permanent oestrus’ might be problematic, or at best over-simplified. One is that the expectation that humans should display oestrus swellings of any sort might be a mistake based on misleading comparisons made with chimps and various monkey species. Pawłowski (1999) argued that humans might lack oestrus swellings as an adaptation to our orthograde bipedality and choice of habitat, but also noted that the idea that swellings were ancestral for our lineage might be erroneous anyway (they aren’t present in gibbons, orangutans or gorillas and, within Hominoidea, might be unique to the Pan lineage).

Another problem with the idea that the female body advertises permanent sexual availability is that it implies or relies on the idea that females are sexually passive and effectively selected by males based on their reproductive potential; it more or less paints a picture of females as home-bound creatures that get protected and cared for by males if they’re plucked from the crowd on the basis of their good genes.

Intrasexual competition among females (implied by this roving gang of intimidating individuals) may be a crucial component of human evolution. This image is from Annalee Newitz's io9 article 'Evolution is steered by aggressive competition between females'.

This scenario looks at odds with what we more typically see in other animals, including primates: females select males as mates and typically choose who mates with them and when, and it’s males who are the showy ones whose evolution has been driven by selection to be sexually attractive. A large body of literature suggests that these generalisations apply across primates, including lemurs, macaques, mandrills, orangutans, chimps and others; in fact, several studies emphasise the importance of intrasexual competition among females, female selection of mates, and the adaptive advantage of promiscuity among females (e.g., Smuts 1987, Paul 2002, Drea 2005). This view isn’t without controversy, however, since some workers have argued that female mate choice in primates is fundamentally limited by male aggression, especially in species with strong sexual dimorphism.

As for humans, there’s little doubt that women are acutely aware of the physical appearance and social status of other women, and some studies show that women are highly competitive – at least as competitive as men (Buss 1988) – when it comes to mate attraction. However, the ability of females to exercise choice is known to be limited by social conditions across primates (Keddy-Hector 1992), and if anything is clear from the conventions and constraints of culture, it’s that people don’t usually get to simply pick up who they like.

Sexual dimorphism is obvious in humans, but size dimorphism is not great compared to that of some of our close relatives. This image of people from the Congo region is from 1902 and is in the public domain.

We therefore have a complex situation where several factors seemingly evolved in tandem: yes, breasts and other features of the human female body do attract male attention and male choice may have contributed to female appearance, but intrasexual competition among females and its link with social standing and hence mate choice may also have been important, perhaps more so. The fact that sexual size dimorphism in hominins is reduced relative to that of other hominids (men are, on average, approximately 15% heaver than women, whereas the size different in gorillas and orangutans is more like 50%) (Larsen 2003, Reno et al. 2003) suggests that a reasonably egalitarian sexual system was ancestral for humans: it was not males in charge all the way.

The human male

To return to that idea that human females are ‘unusual’ as goes our hypothesised ancestral condition, note that the opposite might also be true: male facial and body hair and the bulbous human penis all appear unusual compared to the conditions in other closest relatives. The sometimes thick and extensive beards and moustaches of human males (remember though: extensive facial hair is not a universal male trait of our species) seem to have roles in perceived attractiveness (Dixson & Brooks 2013), a fact which strongly suggests that sexual selection has driven their evolution. Similar claims can be made about other aspects of the male face and jaw.

Facial broadening, the evolution of beards and moustaches and features that enhance gaze and the movements of eyebrows and eyelids are all common trends in primate evolution. This illustration - comparing orangutan and human facial appearance - is by Jonathan Kingdon and is from Kingdon (2003).

How does the ornamented male face compare to that of related primates? Of course, comparative data across all the bits of anatomy we’re interested in have yet to be compiled. However, Weston et al. (2007) documented sexual dimorphism in the breadth-to-height ratio of the upper face in Homo sapiens and found the same sort of dimorphism to be present across the hominins they sampled. It is not present, however, in the faces of chimpanzees, leading them to suggest that, while hominins reduced the amount of sexual dimorphism present within their canine teeth, they compensated for it by increasing facial dimorphism.

Again, however, this doesn’t mean that humans are somehow doing anything especially different from what’s seen in other primates, since other forms of facial dimorphism are present in other lineages: in chimps, orangutans, capuchins and macaques, males have proportionally broader faces than females (Weston et al. 2004). This facial breadth is clearly accentuated in male orangutans by the massive cheek flanges they possess. Note, however, that researchers who have searched for this kind of facial dimorphism in certain human populations have failed to find it (Özener 2012) so it may not be universal.

Cultures and conventions emphasising modesty of dress arguably override the ancestry showiness of our species. Image shows a burqa-wearing woman in Mea She'arim, Israel. Image by Zivya, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

In the end, the bodies of male and female humans both exhibit significant morphological novelties that almost certainly evolved within the context of sexual selection, and we should be perceived as showy primates highly reliant on visual signals of quality. As is the case with other comparisons made between Homo sapiens and other primates, we can better appreciate the evolutionary context of our showiness by looking beyond our nearest relatives – the relatively conservative chimps and gorillas – and at other hominids (orangutans), hominoids (gibbons) and catarrhines (Old World monkeys).

However, never forget that culture and convention are paramount in how humans present themselves to others – the evolutionary pressures that led to our anatomy, behaviour and sexual dimorphism are effectively over-ridden, to a greater or lesser degree, in numerous cultures [adjacent image by Zivya]. Does this mean that they no longer play a role in selection and hence evolution? Well, that’s hard to answer. Meanwhile, in other cultures, dress, convention and tradition mean that sexual dimorphism is emphasised or accentuated, a pattern consistent with claims that anatomical and psychological evolution in humans is occurring faster than it was before.

And finally…

Human social systems are impressively diverse but the existence and maintenance of family groups that belong to extended families and clans have to be considered most typical. Monogamy, polygyny and polyandry are all present in different cultures and it’s worth noting that many stereotypes about divisions of labour between gender groups don’t apply universally across our species. The diversity of social styles and cultures present across Homo sapiens is such a vast subject that I can’t begin to cover it here.

This Asmat woodcarver (from Papua province in New Guinea, Indonesia) encapsulates the complex, flamboyant use of paints, clothing and body decorations seen across many human groups. We are 'extreme' primates when it comes to such accoutrements. Image by Edi Wibowo, licensed under Creative Commons Attribution-Share Alike 3.0 Unported license.

As an addendum to the discussion above about human anatomy and its role in sexual selection, I will end by saying that a major part of our flamboyance comes from the accoutrements we wear or attach to our bodies: tattoos and body paint, piercings and other forms of body modification, jewellery, styled and cut hair, and clothing. Again, the notion that humans have developed extreme versions of trends present within other primates receives support even here, because we know of chimpanzee populations that indulge in ephemeral fashions whereby blades of grass are worn as ear decorations (van Leeuwen et al. 2014). What does, of course, make humans very different from other primates is that, through our use of tools (especially blades), we modify the hair on our heads and bodies, and use clothing to enhance, modify or conceal parts of our bodies.

As I said right at the start of this article, the idea that we might better understand human biology and evolution by making comparisons with other primate species is hardly a novel or innovative idea – it has a long history extending back to Darwin and beyond. And it’s such a vast area with so many facets and relevant areas of investigation that it’s difficult to know where to start. Personally, I think it’s helpful to see us within the context of being ‘just another one of the primates’, but… as for whether this perspective downplays human uniqueness… well, we’re still weird. But then, so are so many of the other primates.

Oh, and this [below] is now available too. It’s at the Tet Zoo redbubble shop.

For previous Tet Zoo articles on Old World monkeys and other primates, do check out…

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Weston, E. M., Friday, A. E. & Liò, P. 2007. Biometric evidence that sexual selection has shaped the hominin face. PLoS ONE 2(8): e710. doi:10.1371/journal.pone.0000710

- ., Friday, A. E., Johnstone, R. A. & Schrenk, F. 2004. Wide faces or large canines? The attractive versus the aggressive primate. Proceedings of the Royal Society of London B 271 (Supp 6), S416-S419.

Wheeler, P. 1992. The influence of the loss of functional body hair on hominid energy and water budgets. Journal of Human Evolution 23, 379-388.

Zihlman, A. 1984. Pygmy chimps, people, and the pundits. New Scientist 104 (1430), 39-40.

- ., Cronin, J. E., Cramer, D. L. & Sarich, V. M. 1978. Pygmy chimpanzee as a possible prototype for the common ancestor of humans, chimpanzees and gorillas. Nature 275, 744-746.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Yodelling Cyclist 10:08 am 07/24/2014

    Don’t go too far with this Darren, because we’re all just big bipedal fish in the end.

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  2. 2. Christopher Taylor 10:10 am 07/24/2014

    This scenario looks at odds with what we more typically see in other animals, including primates: females select males as mates and typically choose who mates with them and when, and it’s males who are the showy ones whose evolution has been driven by selection to be sexually attractive.

    It is my impression that modern Europeans may even be unusual in this regard: in many societies (including Europeans themselves, until reasonably recently), flashy dressing/accessorising is more of a male characteristic than a female one. Think Louis XIV; think John Travolta in Saturday Night Fever. And in New Guinea, I believe it’s generally the men who are rocking the lurid facepaint and faaaaabulous feather head-dresses. Conversely, many societies have held conventions of concealing women from public view, whether through expansive coverings like the Muslim woman you pictured, or through actual seclusion as in classical Greece and Japan (social class, of course, has also been a big factor in all this). So I would question to what extent humans do buck the trend compared to other primates.

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  3. 3. Heteromeles 10:11 am 07/24/2014

    Phooey. You missed the most unique thing about humans, which is that we can make fire*. In this case, I’m talking about making a fire through friction, with a hand drill or similar device. AFAIK, the fossil evidence suggests that firemaking is older than H.s. sapiens, and it’s probably shaped our modern anatomy and evolution.

    Have you ever thought about what kind of anatomy it takes to spin a fire up using a hand drill? It’s not easy to do, for one thing: you’ve got to select the right woods, because you need them sticky enough to transmit enough friction to burn, but not so sticky that you can’t spin them (fire drill spinning raises blisters in unconditioned hands, as I know from personal experience). This is a knowledge skill. You also need to make and use tools to shape the sticks so that they’ll fit together, and so that you can spin it evenly. This requires knowledge and fine tool manipulation. You also need to find, make and fluff up the tinder, which is a fine motor skill. You then need to spin the drill fast enough and hard enough (through precise back-and-forth motion) to ignite a coal through friction, and this critically takes both strength and fine motor control. Finally, you need to transfer the coal to the tinder (fine motor control again), and then use your breath to blow on that coal until it ignites (fine motor control to hold it still, with fine breath control to add air gently enough that you don’t blow the coal out). You then need to know about how to build a fire, but a bonobo can do that.

    Now, think about the combination of knowledge, fine motor control in the hands, strength, ability to apply repetitive motion through the shoulders to spin the drill, through fine motor control to make tinder, control the drill, and transfer the coal, and fine breath control to blow the fire to life through igniting the tinder.

    None of these traits is individually unique, but the combination certainly is. I don’t think any primate or other species has the requisite control of both hands and breath, and I’m pretty sure that many also lack the strength to spin up a fire.

    This is all rather important, because a lot of our tools, and certainly all of our metallurgical technology, come from manipulating matter with fire. I suspect that it’s an accident of evolution that endowed us with the particular suite of characters we used to use to generate fire through friction, but our mastery of fire has allowed us to change the world more than any other species has. No other species makes fire, and I’m pretty sure that no other species has been shown to be anatomically capable of making fire through friction.*

    *Yes, I know Kanzi the Bonobo has been trained to make a camp fire using a lighter. I’d love to see if he can master using even a bowdrill, let alone a hand drill, for making fire. My bet is he can’t, but it would be fun to be proved wrong.

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  4. 4. Christopher Taylor 10:13 am 07/24/2014

    Also, I have to wonder a bit about that map of hairiness distribution. New Zealand is shown towards the hairier end of the scale, but I don’t know if this is accurate.

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  5. 5. naishd 10:14 am 07/24/2014

    Fire: well, I never planned to cover everything here, but it falls into the big bracket of ‘technological innovation’.

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  6. 6. Yodelling Cyclist 10:21 am 07/24/2014

    Are we unique among primates in the lack of a vacuum as well?

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  7. 7. Yodelling Cyclist 10:21 am 07/24/2014

    Damn autocorrect, I meant baculum.

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  8. 8. Jerzy v. 3.0. 10:35 am 07/24/2014

    Primate of interest: bonobo researchers in Congo report another unknown monkey besides already described lesula – with a photo:

    Cool blog to read, if sometimes rather disturbing.

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  9. 9. Jerzy v. 3.0. 10:49 am 07/24/2014

    BTW, I think in humans (like some monogamous birds) there is double sexual selection – both for males and females. Agreed, evolutionary psychologists look at it from the side ‘one sex selects another’ and avoid the issue of within-sex competition.

    I sometimes wonder if there is evidence of bimodal development in human males, like orangutans. With the juvenile-like ‘geeky’ morph recently outcompeting the dimorphic ‘real male’ morph. ;)

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  10. 10. Yodelling Cyclist 10:56 am 07/24/2014

    Do we ever lek breed?

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  11. 11. Tayo Bethel 11:12 am 07/24/2014

    Dr. Naish:
    How many creationists do you think died after reading this? Keep an eye out for outraged pitchfork-wielding primates displaying extreme xenophobictendencies.
    This was fascinating reading … if such a view as this one could be widely accepted i.e. humans as just another primate lineage on the primate tree, who knows what might happen? Not world peace, sadly, but …

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  12. 12. Heteromeles 11:17 am 07/24/2014

    @2: Sometimes, partners aren’t chosen by individuals for sex, but by families to make ties. I think that you’ll find in these cases, the women are more ornamented than they are in settings where they have a choice and pick the males.

    In the US, men are stuck with the remnants of this system (e.g., we don’t get to wear codpieces, flash the bling, and be as ornamental as nature might want us to be), but we do compete with big watches, fast cars, expensive gym bodies, hair pieces, pick-up lines, and similar.

    @9: As for lek breeding, can I suggest (sarcastically) that frat parties are somewhat similar? Certainly, some of the Papuan dance performances are inspired by lek breeding birds of paradise, although I don’t think the women watching are free to all pick their favorite dancer. Certainly, the opposite (females competing for the sexual attention of a male) has happened, most notably in the harems of the Ottoman and Chinese emperors.

    I suspect that what gets in the way of humans using male leks is that it’s pretty impossible for a human female to raise her child without help. Children just need too much in the way of resources and care for a single mother to have a one-night stand and then go off and raise the resulting kid without help from other humans. Yes, women can do kids without husbands, but every parent needs the help of relatives, school teachers, day care, and so forth, just to get the resources needed to keep the kid alive. This probably keeps us from having leks as other species do.

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  13. 13. Heteromeles 11:26 am 07/24/2014

    @5: I agree Darren. The thing is that lots of animals use tools. In fact, if one includes sex toys under the rubric of tool, the number of species known to use tools is in the hundreds.

    Fire’s different. It’s not just the “use a tool to make a tool,” thing, it’s that fire takes a whole, complex suite of anatomical characteristics, and most people don’t think about that. More importantly, fire has enabled us to become ecosystem engineers on a scale that, in geologic history, has been rivaled only by the cyanobacteria (which gave us our oxygen atmosphere) and woody plants (which screwed up the Earth’s carbon cycling system back in the late Devonian and Carboniferous, and possibly caused the Devonian mass extinction). Finally, we’ve coevolved with fire, to the point that I don’t think our species could survive without it. Our jaws and teeth are pretty wimpy for a raw wild foods diet. It’s too bad we’re stuck with the inapt Homo sapiens, because Homo pyrogens might be more appropriate.

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  14. 14. Skulkers 1:34 pm 07/24/2014

    Really great article, and nice to see some popular writing on human evolution that isn’t full of just-so stories.

    @10 and 12: The harems of emperors don’t, I think, in any way count as lekking. In leks, the lekking sex is actively competing for the attention of the prospective sex in a fixed space and very brief amount of time. Imperial concubines undoubtedly competed with one another for influence in the harem but this in no way constitutes lekking behaviour. A harem represents monopolisation of females by an alpha male followed by constant mate-guarding – the closest analogue to an emperor’s harem in other species is a polygamous mating system (like in gorillas). Concubines were selected from the population at large or from noble families (at least in China), and didn’t really have any say in it. The only human situation remotely similar to a lek would be a hypothetical brothel managed jointly and on the free agency of all its prostitutes.

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  15. 15. Andreas Johansson 1:42 pm 07/24/2014

    Just what is that androgenic hair map showing? The numbers seem too low to be percentages of men with beard growth.

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  16. 16. Andreas Johansson 1:46 pm 07/24/2014

    Heteromeles wrote:
    Finally, we’ve coevolved with fire, to the point that I don’t think our species could survive without it. Our jaws and teeth are pretty wimpy for a raw wild foods diet.

    There was a paper some years ago arguing basically that – outside of industrialized agriculture, it’s basically impossible to live on a pure raw food diet for modern humans. Anyone remember the details, and/or know on further research on that front?

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  17. 17. GregMorrow 2:51 pm 07/24/2014

    I have read that humans are also particularly notable in two additional ways: We are proficient throwers, far more accurate than any other primate, and with shoulder adaptations that favor it; and we have unusually high endurance, for long-distance travelling, e.g. we run down horses not by being faster but by never stopping until the horse is exhausted.

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  18. 18. vdinets 3:25 pm 07/24/2014

    Making fire is not universal: natives of Tasmania didn’t have this skill.

    The map of hair distribution shows only native populations in some places but not in others: it apparently reflects European colonization of the Americas, but not Russian colonization of Siberia or Japanese colonization of Hokkaido.

    I often wonder what would have happened to our appearance if the Ottoman harem system became universal and permanently established :-)

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  19. 19. BrianL 4:48 pm 07/24/2014

    Please don’t let us have another man-the-runner discussion. I believe the TetZoo comments section has had two of those already.

    Add me to those who are interested in what the hair distribution map really is about. Is it about general hairiness in human males?

    Certainly there seems to be a great range there, from near chimpanzee level of ‘pelage’ and beards extending to the jugals to universally thin body hair and absence of facial hair. Of course women vary in hairiness in comparable though less extreme degrees as well. Do we know anything about whether or not body hair is even a trait that has been sexually selected for and not just a byproduct of something else, given how variable it (and preference for it) is?

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  20. 20. Yodelling Cyclist 4:59 pm 07/24/2014

    @Heteromeles: hmm, good points about the failure of the lekking model in humans. That said, the idea of males competing for the attention of females is not so unfamiliar amongst humans in Western cultures. The difference being that once selected, the male (in theory!) leaves the lek, mate monogamously and continue to rear the off spring, whereas within, say, Paradisaea the males remain within the lek waiting for more females.

    @Skulkers: “The only human situation remotely similar to a lek would be a hypothetical brothel managed jointly and on the free agency of all its prostitutes.

    ….where the prostitutes are male. Which is not impossible, but is unusual among humans.

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  21. 21. Yodelling Cyclist 5:08 pm 07/24/2014

    @vdnets: Making fire is not universal: natives of Tasmania didn’t have this skill.

    Whoa! Colonisation of Tasmania by humans means crossing the deep water straits separating the Sahul continent from south east Asia. That probably means boats. So you are suggesting a boat building culture without fire? OK< the two skills are distinct, but still.

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  22. 22. Andreas Johansson 5:36 pm 07/24/2014

    Yodelling Cyclist wrote:
    So you are suggesting a boat building culture without fire?

    The usual story is that they had fire, just not the skill to make it anew – if your fire went out, you got a new one from the neighbours, or, failing that, sat around waiting for lightning. Whether this is actually true is disputed.

    Fire-making is one of a number of skills and habits the Tasmanians are supposed to have lost or abandoned post isolation from mainland Australia – their ancestors who crossed deep water presumably had fire-making irrespective of whether some of their descendants lost it.

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  23. 23. vdinets 5:44 pm 07/24/2014

    I also remember reading that although the natives of Terra del Fuego had the fire-making technology, they virtually never used it, preferring to carry fires with them at all times. This is understandable in TdF’s cold and wet climate. I wonder if Tasmanians went through this phase, too, before giving up on fire-making altogether.

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  24. 24. Torvosuchus 5:46 pm 07/24/2014

    Regarding the nomenclature for “apes” versus “monkeys,” I think the problem is the nature of vernacular language itself. The average person tends to group things by outward appearances, which, of course, are often rather superficial when it comes to phylogeny. Non-specialists name ecomorphs rather than clades, basically. (And the less similar to humans, the less precise their colloquial groupings.)

    I mean, “eagles” aren’t all the same evolutionary unit, yet we don’t insist on calling all eagles hawks/buzzards (or vice versa, for that matter), much the same can be said of “vultures,” “antelope” is not commonly understood to include cattle (or “cattle” is not commonly understood to include certain “antelope”), and that’s without getting into such lovely colloquialisms as “bugs” and “trees” that span vast areas of phylospace, yet have just one standard word available for common use.

    I don’t presume to lecture anybody here, just offering some similar examples. So basically I think it’s equally valid to say that “monkey” is an English word that implies a polyphyletic grouping as it is to say that “ape” is an English word that implies a paraphyletic grouping. Six of one, half a dozen of another – pretty much just semantics.

    Still worth discussing if it inspires more people toward tree-thinking. And/or toward understanding why scientists need all them fancy names for critters in the first place.

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  25. 25. Cameron McCormick 6:20 pm 07/24/2014

    At long last Tet Zoo and Mean Girls have finally crossed over! If only I could think of an appropriate quote…

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  26. 26. naishd 6:23 pm 07/24/2014

    Re: comment 25, how about the classic advice from Coach Carr… “Don’t have sex, because you will get pregnant and die! Don’t have sex in the missionary position, don’t have sex standing up, just don’t do it, OK, promise? OK, now everybody take some rubbers”.

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  27. 27. Andreas Johansson 6:27 pm 07/24/2014

    Of interest re Tasmanian fire-making:

    (Despite the title, it’s not all that polemical.)

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  28. 28. TyHieb 6:37 pm 07/24/2014

    Great article! I actually did research on the way we humans think about our relationship/similarities with non-human primates. It was quite interesting since it suggested that most of us view the relationship at the same level despite religious, philosophical and political differences.

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  29. 29. 8:59 pm 07/24/2014

    While I support the use of “monkey” for all anthropoids/simians, including hominoids, there is one downside to it: it robs us of a vernacular term for cercopithecids. They are often called “Old World monkeys”, but if hominoids are monkeys, then “Old World monkeys” would have to refer to all catarrhines.

    On the other hand, Catarrhini never had a convenient verncular term before, so I guess it’s a trade-off.

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  30. 30. 9:01 pm 07/24/2014

    “Colonisation of Tasmania by humans means crossing the deep water straits separating the Sahul continent from south east Asia.”

    CMIIW, but I thought the ancestors of Native Tasmanians were supposed to have crossed over from Australia when sea levels were lower. It seems plausible to me that they might have lost boat-making technology if they’d been living inland for a long time.

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  31. 31. vdinets 9:17 pm 07/24/2014

    My understanding is that most languages don’t have a special word for apes and call them all “monkeys”.

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  32. 32. Christopher Taylor 9:22 pm 07/24/2014

    Sometimes, partners aren’t chosen by individuals for sex, but by families to make ties.

    A fair point, though I’m not sure what the correlation between female choice and female ornamentation would be (western women, for instance, have both a high degree of choice and a high degree of ornamentation). I also wander whether there are implications for whether humans engage in ‘lekking’. As you point out, women in the sort of tribal gatherings referred to above are probably not choosing dancers themselves, but the gatherings do probably offer opportunities for men to impress the women’s families. I suspect this might be especially the case in societies that have strong out-breeding taboos (a man is only allowed to marry a woman from another tribe), where such gatherings may be the main opportunity for women and their families to vet potential suitors. So I wonder if, in a sense, they may be considered a sort of ‘societal lekking’, where the audience of the lek may be the woman’s family rather than the woman herself.

    Certainly, the opposite (females competing for the sexual attention of a male) has happened, most notably in the harems of the Ottoman and Chinese emperors.

    And when I saw this comment, I started wondering about inter-female rivalry in other polygynous species. Presumably, there are advantages within a harem for individual females to try and monopolise the guarding male. Or does this only become a factor when more limited resources than fertilisation itself become a factor? In species where the male is simply corralling females without directly providing for their care, does inter-female competition decline (assuming the male has the fertility to impregnate them all)? All females in harems competing for the male’s attention, or are they competing for the extra resources that come from being the centre of attention?

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  33. 33. Yodelling Cyclist 10:41 pm 07/24/2014

    I thought the ancestors of Native Tasmanians were supposed to have crossed over from Australia when sea levels were lower

    Yes, but my point was that they had to get to mainland Australia in the first place, and that required boats to cross from SE Asia.

    It seems plausible to me that they might have lost boat-making technology if they’d been living inland for a long time.

    Sure, but fire? I mean, cooked meat isn’t just tasty, it’s easier to digest AND has a lower parasite load. Plus there’s the whole warmth thing. Losing the ability to make fire seems really rather careless, and certainly mainland Australian aborigines can start fires.

    I appreciate that a boat can be built without fire, and that the skills are disconnected, but (purely intuitively) I considered fire-making more basal in our technology tree than boats.

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  34. 34. Yodelling Cyclist 10:42 pm 07/24/2014

    I feel the term “quasi-lekking” marching towards this conversation.

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  35. 35. Heteromeles 12:09 am 07/25/2014

    Here’s the thing about the Ottoman system: Basically, each concubine slave got to have one child by the emperor. At that point, the ex-concubines and their children were set up in separate households to make their own way, while the Emperor chose another concubine and repeated the process.

    The Ottoman imperial inheritance process was basically swiped from the Mongols, but with extra bloodshed: the princes competed for the throne, and generally the losers died, lest they become the centers of pretender plots. The second or third emperor realized this, and that’s why the emperors never married and had sex with slaves.

    So this isn’t exactly a typical primate harem, and it was a lot more about the females competing for the status of favored concubine. Otherwise, they were slaves. So far as it goes, this is about as close to a reverse lek as humans can get.

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  36. 36. Heteromeles 12:15 am 07/25/2014

    I’m staying away from the sweaty jogger thread, thanks.

    Getting over to the Tasmanians and Fuegians, the weird connection *might* be the climate. Basically, it’s a pain in the ass to make a fire in cold wet weather, and as I understand it, cold, wet weather is the specialty of both Tierra del Fuego and Tasmania. I wonder if, given how hard it was to make fire, they figured it was easier and safer to carry it with them as much as possible, and to minimize the circumstances under which they had to make a new fire, just for safety’s sake.

    The other thing about the Tasmanian aborigines is that I’m more than a little suspicious about every account of their supposed primitiveness and extinction. For one thing, they’re not extinct, there are a number of part-breed Tasmanian aborigines still living in and around Tasmania. While I think they had an extremely simple life style, I’d suggest a little skepticism when assuming that they were as primitive and degenerate as the conventional stories say.

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  37. 37. Jerzy v. 3.0. 4:55 am 07/25/2014

    “Do we ever lek breed?”
    Ever been to the singles bar?

    ” fire takes a whole, complex suite of anatomical characteristics”

    It would be interesting to compare wrist and arm structure of australopithecines, Homo erectus and H. sapiens for purpose of fire-making. Homo erectus is believed to have fire but its wrists are still anatomically different (but I don’t know how relevant it is to firemaking movements).

    BTW, why other apes on the picture are all males, but the human is female? ;)

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  38. 38. naishd 5:13 am 07/25/2014

    Thanks for all the great comments – some really interesting discussion here.

    Jerzy (comment # 37) says “BTW, why other apes on the picture are all males, but the human is female? ;) ”.

    If you mean the picture I did that shows the assorted representative primates standing next to one another: the individuals I drew were chosen on the basis of how they were posed, not really on gender. Anyway, you’re wrong: the Bonobo and Crested gibbon are female. Only the gorilla and orangutan are male.

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  39. 39. Andreas Johansson 8:30 am 07/25/2014

    Heteromeles wrote:
    I wonder if, given how hard it was to make fire, they figured it was easier and safer to carry it with them as much as possible, and to minimize the circumstances under which they had to make a new fire, just for safety’s sake.

    Precisely that has been argued, frex in the paper I linked to. The author suggests their methods of fire-making only worked reliably in dry weather. This would explain both early reports of aboriginal fire-making and ones of aborigines having to get fire from neighbours if theirs went out.

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  40. 40. Heteromeles 10:26 am 07/25/2014

    Thanks Andreas. When I posted my comment late last night, I didn’t see your link above. It’s interesting: I didn’t know the history of the notion of degenerate Tasmanians until saw the paper, but it’s been such a common strategy in the history of racism (which, unfortunately, I’ve been reading about for something I’m working on, and not to answer Darren’s previous blog) that I’d gotten suspicious just from the little I did know about the Tasmanians, which included our favorite, Jared Diamond, and an article about some Tasmanian aborigines pointing out that they weren’t dead yet, despite claims to the contrary.

    That whole “degeneracy of race” thing looks a lot like the propaganda from back in the age of colonial empires. Making a group sound more primitive than they were was (and probably still is) a common tactic to justify appropriating their land and degrading them. Where I live in California, the Indians were collectively called “Diggers” (which rhymes with a certain N word I don’t use), looked down on because they were so primitive that they didn’t grow crops, they just foraged on acorns and dug roots, and thrown onto reservations after being subjugated by the Spanish, so that Americans could take their land. It was only fairly recently that scientists started wondering why maize cultivation basically stopped at the Colorado River. When they looked at the climate, and read old accounts of how a tribe could harvest a year’s worth of acorns in about three weeks of work, they started realizing that those primitive “diggers” actually were pretty sophisticated in their food choices. They certainly didn’t have to work as hard as the maize farmers did, and maize doesn’t grow well in areas (like California) which don’t get reliable summer rains without irrigation.

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  41. 41. Heteromeles 10:27 am 07/25/2014

    Getting back to the original topic, I must say that, in response to the idea of calling apes monkeys, I can only quote Sir Terry Pratchett’s Librarian of the Unseen University on the subject:


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  42. 42. Jerzy v. 3.0. 10:27 am 07/25/2014

    I heard interesting theory, that non-literary society has a cap of how much technology it can hold, determined by the group size. Basically, when Tasmania became isolated, native Tasmanian society started losing less used technologies by chance, whenever people knowing them died before passing the skill to others.

    Otherwise, they were likely capable people – but the technological difference from Europeans was too extreme to have a chance.

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  43. 43. Tayo Bethel 10:50 am 07/25/2014

    Nice theory … does it standup to scrutiny?

    Hard to imagine a valuable skill like fire[making being restricted to certain individuals in a climate where staying warm was a serious concern. Besides, how closely did the colonizing Europeans study the native Tasmanians? And opinions of such colonizing Europeans was famously biased in favor of the Europeans. The classic case of Europeans encouraging slavery on the grounds that savage” “primitive” Africans needed to be civilized by the Europeans–for their own good, of course.

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  44. 44. Heteromeles 11:04 am 07/25/2014

    @42 Jerzy, I’m sure we cross-posted, so look at #40 when you get a chance.

    Another small comment: people of European descent generally conflate military, communications, and transport technology with all technology. This is understandable, of course (it gave our ancestors empires). However, I’d point out that some of the “technologically primitive” peoples “we” conquered were pretty sophisticated. For example, people in Mexico created maize out of teosinte, and that’s still considered a Nobel Prize-level trick, and one that wouldn’t even get funding if proposed as a research project today (teosinte is a very unprepossessing grass, and somehow maize ended up with more genetic diversity than is found in teosinte today. How’d that happen?). When Cortez conquered the Aztecs (with, not so incidentally, a lot of help from their rebellious vassals and enemies), the Aztec capital of Tenochtitlan was one of the biggest cities in the world, despite the fact that they were militarily a neolithic civilization. The Inka managed to create a huge empire in the Andes, despite the fact that they were governing an area that routinely had upwards of 80% crop failure (crops failed more often than they produced, but the Inka were very, very good at storing food and shipping it where it was needed). When Pizarro conquered the Inka (not so incidentally helped by tens of thousands of rebellious vassals and enemies of the Inkan empire), there were more people living at high elevation in the Andes than there are now, thanks again to indigenous land management practices that scientists are still working to rediscover and reimplement.

    The basic point is that investing in advanced military technology for invading other countries is something that the Europeans of the last 500 years or so have specialized in, and it’s brought our leaders fame and fortune. However, that’s not all of technology, and as subsequent events have proved, we’re actually not that great at a bunch of other technologies, including sustainable land management and, well, sustainability, period. I’d suggest it’s more fun to look at technology as a many-splendored thing, and to see how different groups have invested their efforts in different fields to different effect. Yes, obviously military, communications, and transportation matter, but if you look at the world’s most serious problems (like climate change), they have arguably been caused by over-use of those three technologies, and I don’t think any of them are going to be solved by recourse to the three technologies that we generally consider Technology.

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  45. 45. Yodelling Cyclist 11:21 am 07/25/2014

    @Heteromeles: OK. Um, so?

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  46. 46. vdinets 12:00 pm 07/25/2014

    I absolutely don’t see how the idea that societies consisting of small isolated groups gradually lose certain technologies can be used to justify racism. Don’t Europeans living in small isolated villages lose certain technologies? But, of course, racists always have their own logic that the rest of us can’t begin to comprehend :-)

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  47. 47. Marko Bosscher 12:31 pm 07/25/2014

    Fire may have been important to the evolution of humans, but there are current populations of H. sapiens that can’t make fire (eg. the Sentinelese) and have to carry it around after capturing it from natural sources.

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  48. 48. Andreas Johansson 1:34 pm 07/25/2014

    @Marko Bosscher:
    A habit of carrying around fire doesn’t necessarily imply an inability to make it (cf the Fuegans mentioned upthread). Is enough known about the Sentinelese to tell for sure?

    Tangentially, is anything known about how the Andamanese got there?

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  49. 49. Heteromeles 3:48 pm 07/25/2014

    47@Marko: see above comments about the dubiousness of evidence for the Tasmanians. Since, AFAIK, there’s no one researching the Sentinelese (they’re kind of in a preserve, with no outside contact), is anyone quite sure they can’t make fire?

    Arguably, the biggest group who can’t make fire without matches are us moderns, and look how many fires we set by accident.

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  50. 50. DavidMarjanovic 4:02 pm 07/25/2014

    Oh, I’m not doing the conference circuit this year…

    Not even SVP? There are cheap flights between London and Berlin.

    Really great article, and nice to see some popular writing on human evolution that isn’t full of just-so stories.


    there are current populations of H. sapiens that can’t make fire (eg. the Sentinelese)

    Wait. No outsider has set foot on the island. Somehow I doubt you can tell from flying over it if anyone there can make fire.

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  51. 51. Heteromeles 4:04 pm 07/25/2014

    @46: I know you’re being humorous, but this argument has gone on since probably 1493. It’s about whether it’s just to subjugate people who are technologically inferior to you, and most importantly, whether it’s just to take their land or to enslave them. Throughout that time, quite a lot of people have said it is not just. Unfortunately, we’ve generally lost the argument in practice, if not in theory. Hundreds of thousands, if not millions, of people have died as a result.

    Without going into a long post (I can direct you to references if you want), there’s good evidence that racism was invented to justify conquests. Prior to racial arguments, religious arguments were used to justify the Conquest. For example, Spanish Conquistadors attacking the Puebloan Indians spoke of destroying “mosques” (e.g. kivas) as if the Indians were Muslims and therefore enemies of Christianity.

    As I alluded to above, when we see scientific racism, it’s not coming out of some incomprehensible hate. There’s a lot of money to be made when some group can be theoretically shown to be legally inferior to another, through religion, or currently, science. Unfortunately, I don’t think the problem’s going to go away any time soon. The problem isn’t that equality isn’t real (it is), it’s that equality doesn’t have quite the perceived short-term benefits as inequality to predatory capitalists.

    Argh! Another long post. Sorry!

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  52. 52. gentle lemur 4:05 pm 07/25/2014

    I hate it when I hear zoo visitors referring to anthropoid apes as ‘big monkeys’.
    Why should trivial names reflect current systematics? Surely that might mean that a revision could change both the common and scientific names of a species at the same time! I much prefer the old-fashioned use of the trivial name ‘ape’ to mean any monkey without a tail, such as the Barbary ape. It’s not systematic, but it is clear and straightforward. So a mandrill, which has a tiny but unmistakable tail is a monkey – while a tailless Sulawesi crested macaque can still be called a Celebes black ape.
    In short I’m not convinced that tree-based thinking solves this monkey puzzle.

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  53. 53. naishd 4:58 pm 07/25/2014

    Thanks for all the continuing comments.

    gentle lemur (comment # 52): you needn’t worry that some big change is being made to nomenclature or anything like that. Birds are dinosaurs, but you don’t have to use the word ‘dinosaur’ every time you make an observation about a bird. In exactly the same way, the fact that apes are – from a phylogenetic perspective – monkeys doesn’t mean that we have to stop calling apes ‘apes’. They still are apes and always will be, even though they’re also monkeys, primates, placental mammals, and so on.

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  54. 54. Tayo Bethel 7:19 am 07/26/2014

    Is there really an island that no outsider has set foot on? Sounds incredible.

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  55. 55. DavidMarjanovic 2:03 pm 07/26/2014

    Turns out (unsurprisingly) that that’s apparently not literally true, but it’s close.

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  56. 56. andrewwright73 1:30 am 07/27/2014

    Awesome blog post! :-)
    Re: Sentinelese/Andaman Islanders and their use of fire. Madhusree Mukerjee in her book ‘The Land of Naked People’ (2003) quotes a writer from the 1930s who observed the Greater Andamanese use of an ‘eternal fire’ that was carried around and continually fed with fuel (The writer was James Williams in his book ‘The Spotted Deer (1957)). BTW Mukerjee’s book is a sobering and inspiring read – well worth getting if you’re interested in the Andaman Islands. She gets to Sentinel but doesn’t land, just sees a few of them fishing in a canoe. There’s a Sentinelese contact video floating around on Youtube also.

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  57. 57. Therizinosaurus 3:35 am 07/27/2014

    @52: Because “descended from the common ancestor of Cebus capuchinus and Homo sapiens” tells us a LOT more than “primate without a tail” does and is less subjective since there are millions of morphological features that could be chosen to define taxa but weren’t. It’s just an historical accident that taillessness was chosen as an important feature by some people, whereas the tree of life is an historical fact. As for updating our nomenclature when new knowledge comes in, that’s surely a good thing.

    Your own example is particularly amusing, as the Barbary “ape” (Macaca sylvanus) DOES have a tail in ~62% of individuals (Fooden, 2007). Are 62% of Barbary macaques monkeys? Are humans born with a tail also monkeys, but not the majority of us? Clear and straightforward indeed.

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  58. 58. Heteromeles 11:24 am 07/27/2014

    @52: Because “descended from the common ancestor of Cebus capuchinus and Homo sapiens” tells us a LOT more than “primate without a tail” does and is less subjective since there are millions of morphological features that could be chosen to define taxa but weren’t. It’s just an historical accident that taillessness was chosen as an important feature by some people, whereas the tree of life is an historical fact.

    Nope. The tree of life is not “an historical fact,” it’s a testable hypothesis, subject to falsification.

    This is a subtle but critical point, and it’s the reason cladistics beat out traditional systematics. Traditional systematics was basically expert opinion. Cladistics offered a way to test expert’s hypotheses against the evidence to determine which one was better supported. Cladistics doesn’t always give the right answer, because evolution isn’t always parsimonious, and genes can transfer laterally in most organisms (which happen to be bacteria, not eukaryotes). Quite often, the answer cladistics gives was something the experts “guessed” properly centuries ago (some were true experts after all). But the key advantage of cladistics isn’t that its experts reveal “historical facts” to their admiring followers, it’s that it provides an objective way of testing these “facts” with evidence and supporting or falsifying them.

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  59. 59. naishd 12:00 pm 07/27/2014

    Heteromeles: well… The Tree of life is a historical fact — as is, there is One True Tree, it’s just that our efforts to recover it represent testable hypotheses.

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  60. 60. Zoovolunteer 12:56 pm 07/27/2014

    I find it interesting that all the discussion around human reproductive systems in this thread revolved around mate selection. It seems to me that the most distinctive feature in human biology relates to child care and provision. Even in closely related primates just about all the economic burden for raising an infant falls on the mother, with males and other offspring at best providing some defence and warnings against predators. In humans a large part of food provision for the young and other material needs is provided by other group members, mostly relatives of course but also other connected individuals.

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  61. 61. naishd 4:03 pm 07/27/2014

    Zoovolunteer (comment # 60): interesting point (again, it’s a subject that I couldn’t cover here; the article is already over-long) — but note that, again, humans are far from unique as goes male involvement in the care and provisioning of juveniles. In marmosets and tamarins, fathers and older brothers carry juveniles, share food with them, and are thought to play a major role in the transfer of vocal skills. Extensive male care of juveniles has also been documented in Savannah baboons. See…

    Buchan, J. C., Alberts, S. C., Silk, J. B. & Altmann, J. 2003. True paternal care in a multi-male primate society. Nature 425, 179-181.

    Snowdon, C. T. 2002. From primate communication to human language. In de Waal, F. B. M. (ed) Tree of Origin. Harvard University Press (Cambridge, Mass. & London), pp. 193-227.

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  62. 62. kamion 7:42 pm 07/27/2014

    for as far as I know only in English there is made a distinction between ‘monkey’ and ‘ape’.
    in Dutch there is only one word for both groups nl;’aap’
    I wonder why the English made a distinction.

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  63. 63. vdinets 8:18 pm 07/27/2014

    It seems obvious that women have been shaped by sexual selection more than men. But how exactly did it work? Why did certain features become sexually attractive in the first place? Well, if you look at the list of those features, some of them are those that distinguish women from men, but others (long straight legs, long eyelashes, naked skin etc.) are those that distinguish humans from apes. I wonder if the latter have originally played a role in hybridization avoidance, and if the reason they tend to be more pronounced in women is that it were mostly men who had to be prevented from mating with other species.

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  64. 64. Heteromeles 8:32 pm 07/27/2014

    @61: The Tree of Life is not proven, unfortunately. Yes, there’s one known DNA-based tree of life. However, most prokaryotic species are detected from specimens by extracting DNA from bulk substrate (like soil or seawater) and then sequencing the resulting soup. This practice is known as metagenomics. If you find a cell and fail to get DNA out of it, you’re assumption is that you screwed up, not that you’ve found a cell that doesn’t operate with DNA.

    This is a classic problem from astrobiology–can we detect life that doesn’t use DNA and doesn’t operate using the biochemistry we know? The answer right now is that, especially if such life is microbial, it’s very difficult.

    Let’s put this as a question some astrobiologists have asked: was Earth ever colonized by extraterrestrials? Obviously, the colonization did not succeed (we’re still here), but how do you detect the remains of a failed colony, especially if it occurred millions of years ago? The most likely remnant would be something like the descendents of soil or water bacteria from the colony. But if they don’t use DNA, how would you detect them? You’d spot something that looked like a bacteria or fungus, try to extract its DNA, fail, mark it down as just another failed experiment, and go on. Since I spent a summer doing just this, I can testify that it’s pretty normal to have UFOS (unidentified fungal objects from soil) that it’s impossible to identify. That was about 20% of my samples for my PhD.

    Were any of them alien? Probably not, but by the same token, I think the Tree of Life is a very robust hypothesis, not a historical fact. Since most life (90%?) are microbes and microscopic life forms in the soil and rock, and since most of them are a real pain to identify or even to collect (they occur as deep as we’ve ever tunneled), I’d say that we don’t have the evidence to say conclusively that the Tree of Life is proven beyond all doubt.

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  65. 65. DavidMarjanovic 5:31 am 07/28/2014

    I think the Tree of Life is a very robust hypothesis, not a historical fact

    By “Tree of Life”, do you mean common descent of all known life? I would instead use the term to mean “there is a phylogeny, as opposed to a separate origin of life for every little subspecies” (as Lamarck appears to have thought).

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  66. 66. Dartian 5:50 am 07/28/2014

    Great article, Darren!

    many of the anatomical and behavioural traits once considered unique to humans are not unique at all

    Indeed; especially if we also consider extinct hominin species, there are remarkably few traits that are truly unique to Homo sapiens.

    Regarding anatomical characters, however, there is at least one that seems to be species-specific to us: our protruding chin. No other primates have it, not even the Neanderthals*. (The Flores ‘hobbit’, incidentally, also lacks a protruding chin. That is one of the reasons why the Flores hominin most likely is a distinct species instead of a pathological modern human dwarf.)

    * There are admittedly some Neanderthal-like specimens from the Middle East that have a moderately protruding chin, but whether these should be classified as Homo neanderthalensis or H. sapiens is debated.

    This illustration – comparing orangutan and human facial appearance – is by Jonathan Kingdon and is from Kingdon (2003).

    Lowly Origin is an excellent and thought-provoking book. Recommended! The human in that illustration, by the way, is Kingdon himself. And the orangutans are a Bornean (above) and a Sumatran (below) male; with that picture, Kingdon wanted to show how different their respective appearances can be.

    we know of chimpanzee populations that indulge in ephemeral fashions whereby blades of grass are worn as ear decorations

    Wow! I certainly didn’t know that. Chimps never cease to surprise. ;)

    Yodelling Cyclist:
    Are we unique among primates in the lack of a [baculum] as well?

    No, AFAIK the tarsiers don’t have it, and neither do some New World monkeys.

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  67. 67. naishd 5:53 am 07/28/2014

    Thanks for the comment, Dartian. Of course, I never meant to imply that Homo sapiens lacks autapomorphies.

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  68. 68. 11:37 am 07/29/2014

    ‘My understanding is that most languages don’t have a special word for apes and call them all “monkeys”.’

    This is my impression as well. I’ve been told, however, that Mandarin (and probably other Chinese languages) also splits up the non-human simians into nested paraphyletic groups, but differently from English. There is a word for great apes [sensu stricto], and a word for all simians that are not great apes (monkeys [sensu stricto] and gibbons). I would guess that the word for great apes historically only referred to orangutans. Or perhaps it’s a neologism, and the traditional word for monkeys/gibbons never got applied to them because they were unknown or poorly known to the Chinese for most of history.

    Incidentally, the English words “ape” and “monkey” both originally referred to any Old World simian (other than humans) — New World simians were assimilated upon their discovery. I’m not sure when the terms became differentiated, but it seems to have only happened in the zoological community. It never filtered out much to the Anglophone world at large, which still uses these terms pretty much in their traditional manner (generally favoring “monkey”).

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  69. 69. timcliffe 1:19 pm 07/29/2014

    1. Darren, It astonishes me that so little attention has been paid here to our extraordinary language abilities, although they are very briefly mentioned in your article. By “extraordinary” I mean “in comparison to the communication systems of all other creatures.”
    The power and flexibility of human language distinguishes us from other animals at least as much as our technological abilities, which are in any case highly dependent on language for transmission and teaching.
    Certainly some early technologies could have been passed on by a physical demonstration process (“Show” as opposed to “Show-and-Tell”), but (for example) the very important control-and-creation-of-fire complex would have been difficult to teach solely by demonstration. Best types and sizes of wood, creation of suitable tinder, nursing a spark — these are all things that are easily transmitted by language (with demonstration) versus very laboriously by demonstration only.
    Language allows us to cooperate on a scale and across distances that leave all other creatures far behind. (This includes cooperation for purposes of competition, e.g., between competing groups of humans.)
    Language facilitates our intellectual ability to make complex plans into the near or distant future, but also, crucially, it is absolutely essential to sharing such plans.
    Anyone who ponders the issue must, I think, conclude that our language ability is the most exceptional thing about us. (That’s meant to be a provocative-sounding statement. But consider this: one must use language to formulate complex thoughts, including every single thought expressed in your article and in all the comments above.)

    2. You failed to address Zoovolunteer’s main point: “In humans a large part of food provision for the young and other material needs is provided by other group members, mostly relatives of course but also other connected individuals.”
    Individual humans don’t generally live as hermits, but neither do pairs of humans, nor single-pair families. We virtually always live in interdependent groups.
    Not that that distinguishes us from other primates in some essential way, but it’s almost certainly important in how we evolved our sexual and social repertoire.

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  70. 70. naishd 1:33 pm 07/29/2014

    1. Tim, I think a lot of attention has been paid to our extraordinary language abilities. There are whole books written about it. Within the context of the article here, human uniqueness is acknowledged; so is the fact that we’re part of a rich spectrum that incorporates other primate species.

    2. Yes, humans are social animals that live in interdependent social groups. How is any of this ‘failing’ to address Zoovolunteer’s point?

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  71. 71. timcliffe 2:06 pm 07/29/2014

    Darren: I probably should have started by saying I loved the article for its scope and content, and printed it out for a keeper before I ever commented.

    But its essential point, I think, is to discuss our differences and similarities with other primates, and it seems to me that our language abilities are the biggest difference. It seemed odd to me, then, that language got so little discussion. (I’m talking about the comments as much as the original article here.) Like culture, I realize it’s too big a topic to cover in any detail — but culture (sans language) got at least some discussion.

    Zoovolunteer could say better than I can exactly what he was thinking, but I believe he was asking you and the assembled multitude to talk more about the evolutionary implications of group living on infant provisioning and survival, along with the very interesting discussion of individual-male/individual-female mate selection dynamics.

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  72. 72. naishd 2:11 pm 07/29/2014

    Tim, thanks (not sure why, but I really dislike comments that start with my first name! Seems condescending, though I’m sure this is unintentional)… Yes, human vocal and social abilities are ‘extreme’ compared to those of other primates, but I simply couldn’t begin to cover them once I’d written all the stuff about anatomy and sexual dimorphism. There’s much more on the evolutionary biology of humans that I might come back to at some point in the future.

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  73. 73. Zoovolunteer 2:43 pm 07/29/2014

    I was thinking that in effect humans are cooperative breeders, with other group members taking part in provisioning and raising the young. In marmosets and tamarins other group members mostly provide transport but not food as such. I presume group support for young started because humans were more predatory than related great apes and the group is dependent on sharing the resources of successful hunts, whereas fruit eating or foliage eating as with chimps or gorillas is something that does not require group effort to obtain resources. How to test when the switch between a chimp-style model of child rearing and a more modern human style developed defeats me though.

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  74. 74. naishd 2:48 pm 07/29/2014

    Zoovolunteer: in marmosets and tamarins other group members (most especially fathers and other brothers) do indeed feed babies and juveniles. Humans do, indeed, exhibit an extreme version of a social system present in other primates.

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  75. 75. Heteromeles 8:46 pm 07/29/2014

    I’ve been having a little fun with the whole subject of culture and human child rearing.

    The thing is, culture’s a second type of inheritance, and it’s necessary in humans. We’re far from the only animal with culture: many other species (including raccoons, coyotes, bobcats, apes, ravens, etc.) can only become competent adults by learning from their mothers or other adults. Culture can be a powerful adaptation, in that culture can evolve far faster than genes can, allowing cultural animals to adapt to changing conditions faster than animals that rely only on gene-dependent behaviors. The trade-off is that raising a cultural animal takes a LOT of resources, because the parents or social group has to support an incompetent junior adult until it can live on its own, or support the group.

    Humans take this to the extreme: we have an enormously long learning phase, but we can become anything from aquatic or terrestrial peak predators or strict herbivores, we can nomadic or sedentary, we can create new symbioses through domestication, and we can be ecosystem engineers anywhere from the tropics to the poles, from mountains to deserts. We can also evolve our culture at speeds normally seen only in bacteria. But this astonishing adaptability imposes a huge cost in child rearing, and that cost ultimately limits where we can live. If an area can’t support a group that’s capable of raising children to adulthood, it can’t support humans in the long run.

    As for the cost, if you take the amount of energy used in the US and divide it by the human population, it looks like Americans, on average, use about as much energy as a medium-sized sauropod. An American brontosaurus, if you will (yes, I know it’s Apatosaurus, but there are so many questionable assumptions built into what I just wrote that the old name is more apt). Think about it: apes consuming like sauropods. Who’d have thought it? That’s the power of culture for you.

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  76. 76. Therizinosaurus 2:23 am 07/30/2014

    @Heteromeles- Thanks Darren and David, all I meant by the Tree of Life being objective was that there is a phylogeny. We don’t know exactly what that is yet, and it’s possible some clades emerged independently, (and it’s sometimes a web and not a tree), but evolution did occur in a certain way, which is better to use for taxonomy than whatever morphological trait happens to be in vogue.

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  77. 77. Heteromeles 10:07 am 07/30/2014

    @Therizinosaurus: So objective instead of historical fact as above? Every cladogram is a hypothesis by definition. As noted above, all the DNA-based work strongly suggests that there’s a single origin of the DNA-based life we’ve sampled. Problem is, our methods not only do not sample for alternative life forms, but standard practice with DNA extraction actively excludes anything that doesn’t have extractable DNA, whether it’s alive or not.

    To be honest, I think that the Tree of Life hypothesis is correct, but that’s because I also think that interstellar travel and panspermia are logistically impossible, so there has been no alien colonization of Earth from any source. That’s unprovable speculation on my part (it’s proving a negative, among other things). However, since we’re talking about science and not religion here, I’ve got to argue that the Tree of Life is a hypothesis, not a historical fact as others have stated. Furthermore, it’s one that we’re not actively trying to disprove, at least to my knowledge.

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  78. 78. Anthea Fleming 7:21 am 07/31/2014

    Extremely interesting post.
    1. Humans are the only animal which uses fire? but in Australia Black Kites fly to grass fires to capture lizards and mice etc. escaping the flames – and are known to pick up burning sticks and drop them on the far side of a road or other barrier to the fire. Older birds more accomplished than younger birds, which may burn their feet. Very irritating for human fire fighters.
    2. I have read a claim that humans are the only animal which uses or makes any kind of container – if you’re collecting shellfish before the tide comes in, you need a way to carry a whole lot at once – or for that matter to strip a bush full of berries before a bear arrives. I have no idea who suggested this, but it makes sense as I return from hunting and gathering in the supermarket.

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  79. 79. Dartian 8:01 am 07/31/2014

    in Australia Black Kites fly to grass fires to capture lizards and mice etc. escaping the flames – and are known to pick up burning sticks and drop them on the far side of a road or other barrier to the fire

    I have heard of that – really amazing! Would you happen to know if this behaviour is described in the scientific literature and/or has been caught on film?

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  80. 80. Heteromeles 11:23 am 07/31/2014

    @78, Anthea: Since many plants use fire to cue seed germination, and since many species of raptors (and probably others) hunt along the edges of fires, and since Kanzi the Bonobo was taught to make a camp fire and ignite it with a lighter, I think it’s more accurate to say that humans are the only organism that makes fires through friction.

    It’s neat to hear about the black kites. Unfortunately, I’m not finding any confirmed observations of this behavior, although I see there are a number of videos of black kites patrolling fires.

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  81. 81. vdinets 10:16 am 08/1/2014

    I tried to track the fire-starting kites story a few years ago, and found that there were neither scientifically published observations, nor any known first-hand observations by zoologists. The reason this claim was treated as credible was that it was based on folk stories present in many unconnected cultures. Perhaps the situation has changed by now, but I’m not aware of any published evidence.

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  82. 82. Brian Genda 9:32 pm 08/4/2014

    Darren, like the AronRa video, I started to understand our place amongst the primates when I read this article: It makes sense to me that we are monkeys, but I’m still trying to sort out the implication that we are also fish.

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  83. 83. Caiman 10:06 am 08/19/2014

    if humans are apes and by that logic humans are monkeys, then humans are lobe finned fish.

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  84. 84. naishd 10:09 am 08/19/2014

    That’s right: putting organisms within their nested clades is not controversial.

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  85. 85. florcova 10:57 pm 08/30/2014

    It’s interesting how different it is when it comes to animals including primates and humans in terms of what they look for when choosing their partner or mate. Being a human female, attraction is the number one thing a male looks for before choosing their partner, and all females are very competitive when it comes to looking good for the man your are trying to attract. And I also believe that the male doesn’t have to work as hard as the female to get the attention they want. Now in animals and primates, it states that generally the females are the ones who choose who they want to mate and when and they males are the ones who in some way must show that they are actually attractive both sexually and physically.
    And now what’s also crazy to question is if monkeys do come from apes why call them different names?

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  86. 86. Navid91 2:00 am 08/31/2014

    Cool how we developed are noses and other different body features that are greatly different from most primates

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  87. 87. Troodon 3:06 pm 09/7/2014

    Very fascinating article. It is truly amazing how similar humans are to other primates. It seems to me that, the more research we do, the more we find out that we are really not as unique as we think. And I am not offended at all by the declaration that humans are monkeys. In fact, I am actually proud to be a monkey.

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