Anthropology.net

I don’t know who this is worse for, the editors & reviewers over at Nature or the authors of the article who can’t tell the difference between crocodile teeth markings and stone tool modification, nor raise the possibility. The paper, “Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia,” very confidently proclaims unambiguous evidence for,

“stone-tool-inflicted marks on bones found during recent survey work in Dikika, Ethiopia, a research area close to Gona and Bouri. On the basis of low-power microscopic and environmental scanning electron microscope observations, these bones show unambiguous stone-tool cut marks for flesh removal and percussion marks for marrow access.”

Butchered by early humans or eaten by crocodiles? Image: David DeGusta

Given that the said rib fragment, DIK-55-2, came from a prehistoric lacustrine site. These markings could have been produced by crocodiles. Crocs, if you aren’t aware of (ahem editors and publishing group) are very abundant in the Rift Valley — both currently and prehistorically. On top of that, crocs like to eat meat and scavenge. Yes its true, they are carnivores. Australopithecines were at most ominivores, with wide based teeth useful in grinding tubers and nuts. Crocs have more meat shearing, bone crushing teeth than 3.39 million year old stone tools, which there are none of at the moment.

Given that there really isn’t an archaeological record for Australopithecine tools, I’ll take a gander and say crocs like to eat meat and scavenge more effectively than A. afarensis could make and use said tools to butcher a large ungulate. They have been on this Earth for roughly 197 million years more than hominins have and they are really good at what they do… Again, probably better than a species of hominins who did not live in the Stone Age. It is just as likely (if not more) that the markings were produced by crocodiles just given the ecological context.

Now just how different at cut marks from crocodile teeth marks? David DeGusta, from Stanford University, compared and contrasted the two different markings using images from Njau and Blumenchine (2006) paper titled, “A diagnosis of crocodile feeding traces on larger mammal bone, with fossil examples from the Plio-Pleistocene Olduvai Basin, Tanzania,” to those published in the current Nature article. I’ve inserted DeGusta’s image into this post on right for your own inspection. DeGusta was also on Science Friday, discussing this possibility, with one of the article’s authors, Zeresenay Alemseged. What do you think? Do they look completely different or similar? Seriously, I am asking you to comment. I’d like to know what you see.

Personally I don’t see much of a difference. I agree that stone tools marks are more V shaped, while croc teeth are more pitted/rounded. But take this into light: tool use, especially butchery, is a very human behavioral trait. In their search to attribute this human behavior to a primitive hominin species who roamed 800,000 years earlier, to the era of Australopithecus afarensis, without considering another possible explanation, the authors and editors of Nature were somewhat foolish.

Many paleoanthropologists are in this mad rush to claim their precious find is the most human of hominins, so as to etch their name into the textbooks in rewriting human evolution, that they sometimes forget about doing thorough comparative science. And many publications are in this mad rush to publish the most human of findings, that they sometimes forget about thoroughly editing scientific works. Think that could be the case? I sure do… Why should we settle on secondary evidence for Australopithecine stone tools when none have been found yet, and when another possibility hasn’t been extensively exhausted?

McPherron, S., Alemseged, Z., Marean, C., Wynn, J., Reed, D., Geraads, D., Bobe, R., & Béarat, H. (2010). Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia Nature, 466 (7308), 857-860 DOI: 10.1038/nature09248

Earlier this week, I saw a friend reading this article, and considering SciAm has proven to be a bastion of intellectual stimulation and unbiased discussion, I decided to share it with you. Since the publication of the Neandertal draft genome in May, the concept of reorganizing the human family tree to include Neandertals as a subspecies is not particularly new in the world of paleoanthropology. I wonder why, though, did SciAm decide to publish this discussion now?

Anyways, if you want a synopsis of the thesis of the article, read this excerpt:

“Thus it is—revealing the identity of my example—that we must reclassify Homo neanderthalensis as Homo sapiens neanderthalensis, a subspecies of Homo sapiens. A comprehensive and technically sophisticated study published in the May 7 issue of Science, “A Draft Sequence of the Neandertal Genome,” by Max Planck Institute evolutionary anthropologists Richard E. Green, Svante Pääbo and 54 of their colleagues, demonstrates that “between 1 and 4% of the ge nomes of people in Eurasia are derived from Neandertals” and that “Neandertals are on average closer to individuals in Eurasia than to individuals in Africa.” In fact, the authors note, “a striking observation is that Neandertals are as closely related to a Chinese and Papuan individual as to a French individual…. Thus, the gene flow between Neandertals and modern humans that we detect most likely occurred before the divergence of Europeans, East Asians, and Papuans.” In other words, our anatomically hirsute cousins are actually our genetic brothers.”

I did a real life facepalm when I came upon Shermer’s argument for including them as a subspecies,

“I always suspected that Neandertals and anatomically modern humans interbred, based on a simple observation: humans are the most sexual of all the primates, willing and able to do it just about anywhere, anytime, with anyone (and even with other species…).”

You have to be a paid subscriber to read the rest of article, so I can’t really know if he’s totally serious about his argument or not. Considering he goes on supporting his argument citing the book of human sexual behavior, the Kinsey Reports, I’m afraid that he actually is pretty confident his argument is legit. Sigh.

If this is true, this is a sad state of affairs for scientific publications; when reporters decide to serve up asinine explanations to scientific phenomenon. I am of the opinion that Shermer, nor any reporter, has the position to give reasons to why evolution occurred a certain way. Shermer could have spent his article discussing the differences between anatomy and material culture between the Neandertals and humans, and how the genetic lines of evidence, both mtDNA and nuclear DNA intersect and diverge from those.

He could have synthesized many different schools of thought on Neandertal ancestry and modern human evolution, but he chose to focus on something taboo. Sex certainly sells, I guess even for SciAm… But the thought that modern-ish humans reproduced with Neandertals is certainly not something unthinkable. So why focus on it?