…it was a male who died in Philadelphia in approximately the year 1920. He said that he could very easily rebury the jawbone then claim that he found it in association with H. ergaster. Based off of its appearance and measurements, no one would challenge him.

Interestingly, the same professor has noted that sometimes a bigger fossil sample size makes the answers even MORE elusive. In the case of the miocene apes, the diversity of the fossil record makes a definitive “great ape” family tree very difficult to reconstruct!

I’ve also read the big horn sheep-esque argument for the cranial thickening, but as I recall there were a few other explanations for it floating around, too. (The longer a theory or hypothesis exists the more papers that are published challenging it, after all. ) There seem to be a dozen hypotheses about human body hairlessness alone. haha.

I agree with your comments on the divided opinions of paleontologists. They have so little to work with, they extrapolate from those few artifacts. That, I see as another so human trait–the ability to solve puzzles when we see such a small part of the big picture.

On another note, in regards to the cranial thickening of H. erectus, I’m personally hesitant to ascribe “functional” explanations for morphological characters in fossil species. Being especially partial to behavioural/reproductive ecology, I don’t pretend to be an expert in the means of thickness of the cranium in H. erectus versus H. (or A.) habilis. Is it greatly thickened in the former case? I was under the impression that there was a general trend towards thinner crania, so perhaps its thickness is just an ancestral trait that was under “thinning” selection during the course of H. ergaster/erectus evolution.

Paleontologists are always so divided on that sort of thing; I’m perpetually at a loss when students ask me questions like, “Why were neanderthals short and stocky?” (Another topic where the depth of detail is not appropriate for a blog comment…)

I was searching for pictures of homo erectus brow ridges to use in my Biological Anthropology class and came across this blog. I feel compelled to note that other mammals do in fact “kill their own”. For starters, I recommend that you read Jane Goodall’s “In the Shadow of Man” for its compelling account of murder and infanticide among chimpanzees. In langurs, infanticide is quite often utilized by males to induce estrous in females following a harem takeover. Outside of primates, off of the top of my head I know that it occurs in lions, too. Based off of my knowledge of mammalian mating strategies, I imagine that it occurs in assorted other mammals, too.

(Look: someone even wrote a book about it : http://www.amazon.com/Infanticide-Evolutionary-Perspectives-Glenn-Hausfater/dp/0202020223 )

I understand that it’s easy to romanticise non-human animals and paint ourselves in a more “amoral” light. Alas; it is clear that the precedence for “killing our own” seems to lie very far back in our mammalian heritage.