I've gotten several requests over the last few weeks to address or "debunk" this paper, Impact of Carnivory on Human Development and Evolution Revealed by a New Unifying Model of Weaning in Mammals.
Having now read it several times, my only real response is, "so what?" And that should really be the response of vegans in general to this kind of thing.
It's just one paper, with an interesting mathematical model and a somewhat self-serving definition of what makes a "carnivore." By itself, it neither establishes nor disproves a particular view of human nature or the assumed "natural" diet of H. sapiens. Assuming its model is true, the effect of increased carnivory is likely to be the result of meat's caloric load providing a compact, concentrated source of energy, and not due to any particular nutrient in meat as meat.
And, as the study's authors themselves caution, the paper in no way implies that meat consumption is necessary for humans today. After all, we have many non-meat sources of concentrated calories in compact form, and there are plenty of healthy, well-developed vegan children in the world. One of my fellow students in bio, I recently learned, has been vegan from birth... and she is one of the healthiest people in our class, if body composition and blood bio-markers are any indication. No growth issues or vitamin deficiencies in her case, anecdotal though it may be.
So yeah, carnists. So what?