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Hip Hop Evolution Files: Defining Polyandry

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


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From SouthernPlayalisticEvolutionMusic on the Southern Fried Science Network.

********************

Often I am asked, “How do you come up with posts? Do you read a paper/see a talk and come up with a song or do you hear a song and try to come up with a paper for it?” The answer is both. But for this particular post, it was the song first. I love this song, the rhythms and synthetic drums pulsing in the background. It is my jam, indeed. (And I know I am dating myself).



Oh Sheila by Ready For The World

Anyway, I was rocking this song out on my drive to my parents’ home. I kept pushing repeat and as I listened and re-listened to the lyrics of this song, I thought to myself, there is a behavioral concept here, I just know it. And then it hit me, this song could be the love ballad of the male Galapagos hawk.

Galápagos Hawk (Buteo galapagoensis) on Fernandina Island by Hans Stieglitz

Galápagos Hawk (Buteo galapagoensis) on Fernandina Island by Hans Stieglitz

The Galapagos are the Mecca of Evolutionary Biology. Charles Darwin, spent a little of his time there and made some amazing observations that really rocked the scientific world. The Galapagos are a series of islands (some not inhabited at all by humans) near the equator way off from Ecuador, South America. On these islands live a raptor species, the Galapagos Hawk, Buteo galapagoensis. This bird is native and endemic to the islands and have been geographically and genetically separated from similar hawks on the mainland for about 300,000 years. It’s a closed system. And in such small party situations, it shouldn’t be much of a surprise for the natives to make their ‘own rules’ when it comes to love.

The Galapagos hawk is one of the few known species that engage in polyandry. Yes, the mating system where the female has two or more mates. A female will mate with her ‘husbands’ and she and her harem of 2-7 fellas will build a nest, brood the egg and feed and defend the chick until adulthood. Yeah, you read right. On average, there’s only a single offspring born per season.
I mean it’s one thing to be co-hitting that with someone – say like in dogs or cats, where at least you know the female will have more than one baby at a time and a guy has a chance to get a few offspring out of it. But 1 offspring and they splitting it seven different ways! That just sounds crazy, right? That’s one big fitness gamble. It certainly is. The thinking is that the environmental conditions of the islands make it so that not every male can find/keep his own mate and raise their own set of chicks. The Galapagos are pretty, but they aren’t lush like that – just not enough prey to go around. So, males are quite tolerant of one another.

For the female, the fitness benefits of this mating system ensures that she will definitely get her eggs fertilized (and have chicks) because she is mating with more than one male. Related to this point, no doubt there is some sperm competition between the males. In cases where the female does produce two chicks, have multiple fathers means more genetic variation. Variation is always a good thing (in the evolutionary sense) because this variety means perhaps at least one of her offspring can handle whatever curveballs come its way in the future. Since all males have an equal chance of fathering the offspring, this means each will likely provide parental care to the offspring. This means more overall food provisions for the female while she is brooding and more food delivered to the chick, too, once it comes. Moreover, since no male knows if the offspring is/is not his in any given season, this discourages each of them from engaging in infanticide.

The benefit to males include better survival success for the chicks. Studies in closely related species where both polyandry and monogamy have been observed, chicks raised by only two parents get feed less and this affects their survival. So, sharing paternity and raising a healthy chick is better than having no offspring at all.

Confirmation of cooperative polyandry in the Galapagos hawk (Buteo galapagoensis). 1995. J. Faaborg, P. G. Parker, L. DeLay, Tj. Vries, J. C. Bednarz, S. Maria Paz, J. Naranjo and T. A. Waite. Behavioral Ecology and Sociobiology. Volume 36, Number 2, 83-90.
DOI: 10.1007/BF00170712

Oh Sheila by Ready For The World
Like they always say
What’s good for the goose
Is always good for the gander
Oh, Sheila
(Oh, Oh)

So often we are bombarded with accounts and stories of polygamy in the animal kingdom. I’m quite tickled to share this one with you all.

Oh, Baby
Love me right
Let me love you till we get it right, Hmm
Can’t you let the others be
‘Cause with you is where I got to be
Oh, Sugar
Where you been
Hangin’ out with your male friends
(Listen)
Somebody’s gonna hurt you
The way you love to keep hurting me
(And we sing)
The sex ratio is quite biased (more males than females). I bet each male really does ‘got to be’ with the female he is with. But alas, female Galapagos hawks have it good, and I’m sure she has no intention to break their hearts, that’s just how it is on the archipeligo.

[CHORUS]
Oh
Oh, Sheila
Let me love you till the morning comes
Oh
Oh, Sheila
You know I want to be the only one

Oh, Baby
Understand
That I want to be the only man
But it seems as though it’s getting too hard
And I think I’ll start to have my own friend
Oh, Baby
It’s plain to see
That you’re qualified to fufill your needs
You think you pulled one over on me
Well, Honey
Baby, just you wait and see
(And we sing)
I am sure each male would very much like to be the only one. And if he could find his own lady, all to himself, he would. It would be to a male’s advantage to belong to a group with the fewest number of males to yield the highest benefits and likelihood of success. So sharing parternity with one or two othr males is a much better situation than sharing a female with seven others. Good thing the average number of males in a cooperative mating group is two – another reason why this system might be maintained for so long. The group size stays in check, overall.

[CHORUS]

Uh, Baby
It’s 1-2-3
I love you baby, Honestly
Hmm, I want to
Di a di da li a di a di da li

Oh
Oh, Sheila
Uh, uh, uh
Oh, Sheila
Oh
Oh, Sheila
Uh, uh, uh
Oh, Sheila

Oh, Baby
Love me right
Let me love you till we get it right, Hmm
Can’t you let the others be
‘Cause with you is where I got to be

Oh, Baby
Understand
That I want to be the only man

You think you pulled one over on me
(Well, honey, baby, just you wait and see)
(And we sing)

[CHORUS] x 2

DNLee About the Author: DNLee is a biologist and she studies animal behavior, mammalogy, and ecology . She uses social media, informal experiential science experiences, and draws from hip hop culture to share science with general audiences, particularly under-served groups. Follow on Twitter @DNLee5.

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





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  1. 1. Sean McCann 12:01 pm 08/30/2011

    Nice article on a cool species! I study a system that just may be similar: the Red-throated Caracara(http://farm5.static.flickr.com/4062/5159845899_964b7ca3d0_b.jpg). I have recorded up to 6 adult-plumage birds provisioning a single offspring (there were actually 7, but the referees disagreed).Some of these are males and some are females.
    If anyone wants reprints, my gmail is smccann27

    Link to this
  2. 2. Sean McCann 12:06 pm 08/30/2011

    Oh yeah, here is the article abstract (in Spanish only)
    http://www.bioone.org/doi/abs/10.3356/JRR-09-75.1

    Link to this
  3. 3. jgrosay 6:44 am 08/31/2011

    Galapagos are not the only species that engages in polyandry, humans do or did this before. As examples, in the Balearic islands, a tradition existed in prehystorical times that all men invited to a wedding had intercourse with the bride during the wedding party; in the ancient Egypt, free people preferred not to broke his wife’s virginity, and left the task to a domestic or to an slave. In the canary island of Lanzarote, before the arrival of the conquistador Bethencourt, women used to have several husbands, one of them acting as principal husband and staying at home, while the others went out for agriculture work or fishing; the position of main husband was subject to shifts, and with the new moon, another husband will start acting as husband at home, and the former returned to the production jobs.

    Link to this

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