It's been pointed out elsewhere that Wrangham doesn't actually have any evidence whatsoever for his cooked-tuber theory(eg:- www.beyondveg.com has a section debunking his claims re tubers) - he even admitted he had no genuine evidence for his claims in one article on the subject. The trouble is, also, that wildfires started by lightning are common in East Africa, which means that simply stating that any evidence of a million-years-old fire must have had a human origin is quite absurd. Another big problem with the idea re the advent of cooking supposedly leading to larger human brains is that you need already to be highly intelligent in order to invent fire as it is such a complex process(at least, I have yet to see any evidence of lesser primates understanding fire, let alone knowing how to start it) - if you don't believe me, try lighting a fire with with just 2 sticks, the wind blowing around you, while you're in a slightly wet climate etc.. Heck, even without those hindrances,  using 2 sticks, as opposed to matches/tinderboxes etc. is a hell of a business.
 
As for the claims re increased energy with cooked as opposed to raw foods, they're absurd. With cooked-foods I feel sluggish, and have to eat far more before I feel sated - raw foods tend to have higher vitamin-levels etc. and so I need less of them, per meal, by contrast.
 
Also, Wrangham has a very big problem trying to explain away the fact that Homo Habilis was also, just, like Homo Erectus, the result of significantly increased brain-size, by comparison to previous ancestors. He tries to explain it away as the result of eating (uncooked) meat, but then uses an entirely different explanation(cooked-food) to explain a similiar extra boost in brain-size  by Homo Erectus. It seems more logical to assume that there is a common explanation for the increased brain-size of both species. Also, Homo Erectus had a much higher meat-intake than Homo Habilis(and a much larger brain), thus supporting the meat/larger-brain theory, rather than Wrangham's ideas.
 
Personally, while the meat-consumption/brain-theory sounds good, I'm more convinced that there is a non-dietary reason for our larger brains.
 
Geoff
 
> > Date: Fri, 11 Jan 2008 09:41:58 -0300> From: Juergen Botz <[log in to unmask]>> Subject: Cooking made us human..?> > Each year Edge Magazine asks an "annual question" of 100 of the worlds th=> inkers... this years question is "what have you changed your mind about",=> and anthropologist Richard Wrangham's answer is of interest to this list=> . You can find it here: <http://www.edge.org/q2008/q08_9.html#wrangham>.=> The full text of his answer is reproduced below.> > -:----------------------:-> > RICHARD WRANGHAM> Professor of Biology and Anthropology, Harvard University' Coauthor (with=> Dale Peterson), Demonic Males: Apes, and the Origins Of Human Violence> > > The Human Recipe> > Like people since even before Darwin, I used to think that human origins => were explained by meat-eating. But three epiphanies have changed my mind.=> I now think that cooking was the major advance that made us human.> > First, an improved fossil record has shown that meat-eating arose too ear=> ly to explain human origins. Significant meat-eating by our ancestors is => initially attested in the pre-human world of 2.6 million years ago, when => hominids began to flake stones into simple knives. Around the same time t=> here appears a fossil species variously called Australopithecus habilis o=> r Homo habilis. These habilis presumably made the stone knives, but they=> were not human. They were Calibans, missing links with intricate mixture=> of advanced and primitive traits. Their brains, being twice the size of => ape brains, tell of incipient humanity: but as Bernard Wood has stressed,=> their chimpanzee-sized bodies, long arms, big guts and jutting faces mad=> e them ape-like. Meat-eating likely explains the origin of habilis.> > Humans emerged almost a million years later when habilis evolved into Hom=> o erectus. At 1.6 million years ago Homo erectus were the size and shape => of people today. Their brains were bigger than those of habilis, and they=> walked and ran as fluently as we do. Their mouths were small and their t=> eeth relatively dwarfed =E2=80=94 a pygmy-faced hominoid, just like all l=> ater humans. To judge from the reduced flaring of their rib-cage they had=> lost the capacious guts that allow great apes and habilis to eat large v=> olumes of plant food. Equally strange for a =E2=80=9Chelpless and defence=> less=E2=80=9D species they had also lost their climbing ability, forcing => them to sleep on the ground =E2=80=94 a surprising commitment in a contin=> ent full of big cats, sabretooths, hyenas, rhinos and elephants.> > So the question of what made us human is the question of why a population=> of habilis became Homo erectus. My second epiphany was a double insight:=> humans are biologically adapted to eating cooked diets, and the signs of=> this adaptation start with Homo erectus. Cooked food is the signature fe=> ature of human diet. It not only makes our food safe and easy to eat, but=> it also grants us large amounts of energy compared to a raw diet, obviat=> ing the need to ingest big meals. Cooking softens food too, thereby makin=> g eating so speedy that as eaters of cooked food, we are granted many ext=> ra hours of free time every day.> > So cooked food allows our guts, teeth and mouths to be small, while givin=> g us abundant food energy and freeing our time. Cooked food, of course, r=> equires the control of fire; and a fire at night explains how Homo erectu=> s dared sleep on the ground.> > Cooked food has so many important biological effects that its adoption s=> hould be clearly marked in the fossil record by signals of a reduced dige=> stive system and increased energy use. While such signs are clear at the => origin of Homo erectus, they are not found later in human evolution. The => match between the biological merits of cooked food and the evolutionary c=> hanges in Homo erectus is thus so obvious that except for a scientific ob=> stacle, I believe it would have been noticed long ago. The obstacle is th=> e insistence of archaeologists that the control of fire is not firmly evi=> denced before about a quarter of a million years ago. As a result of this=> archaeological caution, the idea that humans could have used fire before=> about 250,000 to 500,000 years ago has long been sidelined.> > But I finally realized that the archaeological record decays so steadily => that it gives us no information about when fire was first controlled. The=> fire record is better at 10,000 years than at 20,000 years; at 50,000 ye=> ars than 100,000 years; at 250,000 years than 500,000 years; and so on. E=> vidence for the control of fire is always better when it is closer to the=> present, but during the course of human evolution it never completely go=> es away. There is only one date beyond which no evidence for the control => of fire has been found: 1.6 million years ago, around the time when Homo => erectus evolved. Between now and then, the erratic record tells us only o=> ne thing: the archaeological evidence is incapable of telling us when fir=> e was first controlled. The biological evidence is more helpful. That was=> my third epiphany.> > The origin of Homo erectus is too late for meat-eating; the adoption of c=> ooking solves the problem; and archaeology does not gainsay it. In a roas=> t potato and a hunk of beef we have a new theory of what made us human.=20> > -:-> > ------------------------------> > End of PALEOFOOD Digest - 10 Jan 2008 to 11 Jan 2008 - Special issue (#2008-9)> ******************************************************************************> 
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