A new species of shrew has been found in Africa, and it has the mightiest, most extraordinary backbone of all the mammals.
A little more than a century ago, the first species of African hero shrew (Scutisorex somereni) was found in Uganda by British zoologist, Oldfield Thomas. While Thomas noted the creature's long, thick fur, and relatively large 70 g body, he missed the most fascinating part of his discovery - a massive spinal column unlike anything seen in any other mammal. Its existence remained unreported for almost a decade afterwards, until Joel Asaph Allen, curator at the American Museum of Natural History, found a preserved hero shrew in his collection in 1917, and discovered its secret superpower.
Between our rib cage and pelvis, we have five specialised vertebrae called lumbar vertebrae. Allen found that the African hero shrew can have up to 11 lumbar vertebrae, and each is fortified by a unique interlocking arrangement that makes the entire backbone super-strong. This was no news to the locals that lived alongside the species - the Mangbetu people of the Democratic Republic of the Congo (DRC) named it "hero shrew" long before it was given its scientific name. German-born naturalist, Herbert Lang, spent some time with the Mangbetu as leader of the American Museum of Natural History Congo Expedition in the early 1900s, and described their relationship with the shrew in Allen's 1917 paper:
"These people feel convinced that its charred body or even its heart, when prepared by their medicine-men, transmit truly invincible qualities, if worn as a talisman or taken like a medicine. Perhaps this mystic reputation has often contributed to make of a brave man a real hero, wherefore the Mangbetu gave it a name meaning "hero shrew" ... Though only worn somewhere about their body, they believe that neither spears nor arrows, nor any kind of attack can seriously injure them, much less bear them down. One can easily imagine that by the removal of the inhibitory influence of fear, their courage, cunning and cleverness are set free for the best possible achievements."
Not only did the African hero shrew serve the Mangbetu as a heavily charred defensive charm, it also played the part of a rather unwitting party trick, as Lang would go on to describe:
"Whenever [the Mangbetu] have a chance, they take great delight in showing to the easily fascinated crowd its extraordinary resistance to weight and pressure. After the usual hubbub of various invocations, a full-grown man weighing some 160 pounds (72 kg) steps barefooted upon the shrew. Steadily trying to balance himself upon one leg, he continues to vociferate several minutes. The poor creature seems certainly to be doomed. But as soon as his tormentor jumps off, the shrew, after a few shivering movements, tries to escape, none the worse for this mad experience and apparently in no need of the wild applause and exhortations from the throng."
Ah, when scientific papers were as entertaining as any good book.
While Allen and Lang recognised that the strength of the African hero shrew's backbone and strong shoulders acted to protect its vital organs from the crushing weight of an entire man, they could not propose a viable explanation as to why it existed in the first place. Of all the mammals in the world, why was this the only one with massive, interlocking lumbar vertebrae?
And then a new hero shrew emerged, as a number of small mammals were picked up in 2012 near the village of Baleko in the Equateur Province of the DRC. "It was not immediately obvious that this was a hero shrew, or even a new species of hero shrew," says the leader of the team, William Stanley, Head of Collections and Negaunee Collection Manager for Mammals at Chicago's Field Museum of Natural History. "Only when we analysed the DNA and took a close look at the skull and vertebral column did the significance of what we found sink in."
What they'd found was the second-known species of hero shrew, Scutisorex thori - to be commonly known as Thor's hero shrew. Described in today's edition of Biology Letters, the new species is smaller than S. somereni, and less woolly, and while the strength of its backbone hasn't been tested quite so definitively as S. somereni's, its eight interlocking lumbar vertebrae suggest similar greatness.
Both species inhabit Africa's swampy palm forests, and it's this preference that has given us the best clue for why they would need such massive, fortified backbones. The locals frequent these forests to collect the nutritious beetle larvae that hide between the palm trunks and the hardened bases of dead palm leaves, so Stanley's team suspects that the hero shrews sustain themselves by doing the same. "One of the co-authors, Lynn Robbins, worked in DRC in the 70s and asked local residents where he could find hero shrews," he says. "They told him this shrew was commonly seen near palm trees."
Knowing that the locals were pulling the base of the dead palm leaves away from the trunks to gain access to the large grubs, Robbins suggested that the hero shrews were doing the same - their long, fortified spines giving them the strength to leverage the leaf bases away from the trunk. So super-spines could give Thor's hero shrew access to a secret wealth of grubs and other insects, while everyone else is forced to scavenge for their meals in the mud and undergrowth. The team will continue to study both species of hero shrew, and they're hoping catch at least one of them in this 'leaf-levering' act.
And here's a video of a completely different species of shrew digging holes in a beach because it doesn't have a backbone of steel:
My book, Zombie tits, astronaut fish and other weird animals, is now available in the US. Order from Amazon.