Wrangham = Wrongham

[PaleoPhil]

A nice summary of why Wrangham went Wrongham:

Our Takeaway (so far)

• Our ancestors’ dietary shift towards ground-based foods, and away from fruit, did not cause an increase in our ancestors’ brain size.
• Bipedalism was necessary to allow an increase in our ancestors’ brain size, but did not cause the increase by itself.
• Bipedalism allowed A. afarensis to spread beyond the forest, and freed its hands to carry tools. This coincided with a 20% increase in brain size from Ardipithecus, and a nearly 50% drop in body mass.
• Therefore, the challenges of obtaining food in evolutionarily novel environments (outside the forest) most likely selected for intelligence, quickness, and tool use, and de-emphasized strength.
• By 3.4 MYA, A. afarensis was most likely eating a paleo diet recognizable, edible, and nutritious to modern humans.
• The only new item was large animal meat (including bone marrow), which is more calorie- and nutrient-dense than any other food on the list—especially in the nutrients (e.g. animal fats, cholesterol) which make up the brain.
• Therefore, the most parsimonious interpretation of the evidence is that the abilities to live outside the forest, and thereby to somehow procure meat from large animals, provided the selection pressure for larger brains during the middle and late Pliocene.
  

The Paleo Diet For Australopithecines: Approaching The Meat Of The Matter (Big Brains Require An Explanation, Part IV)
J. Stanton
http://www.gnolls.org/2837/the-paleo-diet-for-australopithecines-approaching-the-meat-of-the-matter-big-brains-require-an-explanation-part-iv/[/size]

[cherimoya_kid]

I still don't see why evolving larger brains requires a reason.  Dinosaurs were evolving larger brains before they were wiped out. Mammals are following the same path.  Towards the end of the dinosaur times there were a number of smaller, more intelligent dinosaurs with larger brains, in addition to the larger, dumber ones.  The same is pretty much true now, of mammals, except that we haven't had an extinction event like they experienced; therefore, we have had the opportunity to go father in the direction of evolving larger brains.

Why complicate things?  Vertebrates evolve larger brains, over time. It's not something unique to primates or even mammals.

[PaleoPhil]

For those who are interested in the reason, which includes many scientists, Wrangham tried to provide one, but I think he is off base. Those who aren't interested in a reason of course, don't feel any inkling to look for or hypothesize one, which is fine too. To each their own. If there's some sort of natural automatic brain-growing process in all mammals, that would also be a reason, but scientists would look for what that process is and the details of how it works, and look for what changes occur in it during periods of brain growth versus periods of relative brain-size stasis.