Most complete Paranthropus boisei skeleton found

The most complete Paranthropus boisei skeleton found reveals that this species was larger than believed, on par with Homo erectus. What’s more it was strong and bulky; and may well have climbed trees


The Paranthropines were a bizarre offshoot of the human family that lived from 2.7 – 1.3 million years ago. They were our cousins, who lived alongside Australopithecus (like Lucy and Au. sediba) and later our own genus, Homo. Although part of our family they looked nothing like us, with huge jaws and an odd-looking cranium, distorted by evolution to accommodate their huge chewing muscles 

The skull of P. boisei (right) and Homo erectus (left)

The skull of P. boisei (right) and the contemporary, more human-like Homo erectus (left)

Recently dated teeth show Paranthropus boisei was alive in Africa just 1.33 million years ago; making them the youngest Paranthropines. They lived alongside Homo erectus – the species that would eventually become us – who was looking very modern by this point.  They had a large brain, was creating beautiful stone tools and was a tool, upright biped. They were even beginning to spread out of Africa and round the world. Meanwhile what was P. boisei doing? Well we don’t really know, given that we’ve found very little of their skeleton. Some very pretty (well what passes for pretty amongst gorilla-men) and complete skulls yes; but not much else. A handful of shattered legbones and pieces of foot, but nothing that substantial.

knmer1500

KNM-ER 1500. Prior to this the most complete P. boisei skeleton found

Fortunately these teeth – details of which were only published in December of last year – were associated with an in situ (that is, undisturbed) skeleton; which consisted of a partial humerus, radius, femur and tibia, all of which appear to have been gnawed on by scavengers. It might not sound like much, but when KNM-ER 1500 (that picture on the right) is the best we’ve got; it is a huge improvement. But what can it tell us about P. boisei?

Well the first notable thing about this skeleton – known as OH-80 – is the sheer size of the beast. This individual stood 1.5 m tall and weighed between 40 – 60 kg. That puts them about on par with Homo erectus, who typically stood between 1.4 – 1.8 meters tall and weighed 40 – 68 kg (there will be no imperial conversions for the yanks; on general principle). What leaps out here is that whilst OH-80 is ~20% smaller than the tallest Homo erectus, they’re only 10% lighter than the heaviest. In other words they were a lot more heavily built.

Which is the second most notable thing about the skeleton: it’s very robust. The bones are thick and strong, again supporting the idea they were very heavily built. Their arms in particular appear to be much longer and stronger than what contemporary humans had. In fact, their radius and humerus are actually the largest and strongest of any member of the human family yet discovered; and show remarkable similarities to orang-utans (who spend a lot of their time climbing trees). Perhaps this indicates that, bulky as they were, Paranthropus boisei was an adept climber that spent a lot of time in trees.

The other interesting thing is that they’re not only big compared to Homo erectus, they’re big compared to the other P. boisei skeletons we’ve found. Granted, the KNM-ER 1500 fossil is in tiny tiny pieces, but it still seems to have been much smaller than this new discovery. This seems to suggest that there was a fair bit of sexual dimorphism amongst the species, with the males being much larger than the females. Again, this stands in stark contrast to Homo erectus; which was only the most sexually equal species of human (size wise I mean, I suspect there was not a strong suffragette movement in the Pleistocene).

The arm and leg bones of OH-80

The arm and leg bones of OH-80

In short, they’re much bigger and stronger than anyone anticipated (although the sexual dimorphism was expected); and would’ve been as tall as any contemporary humans. Even compared to us moderns they wouldn’t seem unusually short. Despite that they were still adept climbers, apparently behaving a lot like apes. tl;dr: these weird looking human cows have taken an even weirder turn.

References

Domínguez-Rodrigo M, Pickering TR, Baquedano E, Mabulla A, Mark DF, et al. (2013) First Partial Skeleton of a 1.34-Million-Year-Old Paranthropus boisei from Bed II, Olduvai Gorge, Tanzania. PLoS ONE 8(12): e80347. doi:10.1371/journal.pone.0080347

Wood, B., & Constantino, P. (2007). Paranthropus boisei: fifty years of evidence and analysis. American journal of physical anthropology134(S45), 106-132.

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6 thoughts on “Most complete Paranthropus boisei skeleton found”

  1. john zande says:

    Human cows… Brilliant turn of words.

    I think you made a typo here: “was creating beautiful stone tools and was a *tool* (tall?), upright biped.”

  2. clayton says:

    Well, to me this is funny, because speaking as a layman, and a Yank layman at that, this is how I pictured Paranthropus Boisei anyway. The things I read as a kid tended to make you think boisei and robustus WERE bigger than Australopithecus, but then I would read something that said they were only referring to the skull structure. I would think, Right, whatever. You educated types always try to take the fun stuff out of it. And look—turns out I was right after all! These dudes were probably muscular bad-asses, similar to gorillas, with a big male and a bunch of babes and babies to guard. They would probably mind their own business until some pesky H.Erectus or other would risk coming in to grab a baby, perhaps using advanced weaponry like sharpened sticks and clubs. War of the Stone-Age Men! Erectus needed the weapons, because Paranthropus was strong—I picture a stand-off, with the big male and the older juveniles covering the retreat of the females and young, a lot of screaming, rushing, branch shaking, and the Erectus hunters move on for easier prey, or a better opportunity. I know it might be a little dramatic, and most mainstream paleo-anthros would doubt it, but you’ll probably find proof of such a scenario in 10 or 20 years, and be all astounded. Just ask me, I’ll tell ya!

    1. Adam Benton says:

      It’s worth noting that the gracile Australopiths also seem to have been a bit taller than we thought as well. For years our view was influenced by Lucy, who seems to have been quite small for her species after all.

      1. clayton says:

        That is interesting—It seems to me that the situation for evo-anth scientists is this: that while they categorize fossils by their various traits into their various species and other groups, the fossils themselves are actually quite rare, and thus they may not truly represent the “typical” individual of any given species. Especially when you you take into account the amount of diversity among individuals of a population. So, as time goes by, the definitions change, or maybe “evolve”, as more evidence is found. Am I close?

        1. Adam Benton says:

          This is something to consider and was more of an issue in earlier research. The distinction between Homo erectus and Homo ergaster seems to just be the result of regional variation in a species. That said, researchers are getting better at appreciating the degree of variation in a species. After all, despite the height variation in the fossils mentioned, researchers were able to recognise them all as part of the same species.

          However, a part of this variation is also temporal. You might not see such extreme variation in members of the species living at the same time, but it would change over time. We know something similar has happened in humans. On average we used to be a lot taller, for example.

  3. clayton says:

    Oh, I also wanted to speak about the climbing ability of Paranthropus—it must have been pretty awesome! I’ve read a lot of things here and there about how gorillas, being heavy, don’t climb trees as adults, or climb much anyway, but I’ve seen video of big Silverbacks climbing huge trees with ease, and with speed, chasing a female or juvenile to dole out justice. So I imagine that a Paranthropus, big and bulky yes but not near the size of a gorilla, would be able to climb pretty damn well.

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