Early man development

But growing brain size presented a metabolic problem. A gram of brain tissue takes 20 times more energy to grow and maintain than a gram of tissue from the kidney, heart, or liver, she said. Gut tissue is metabolically expensive too — so as brains grew gut sizes shrank.

It’s likely that meat eating “made it possible for humans to evolve a larger brain size,” said Aiello. Early human ancestors probably consumed more animal foods — termites and small mammals – than the 2 percent of carnivorous caloric intake associated with chimpanzees.

The social implications of increased meat eating were interesting, said Aiellio. In most primates, there’s no food sharing between females and offspring, she said. But the difficulty of getting meat led to cooperative food sharing among early humans, strengthening the bond between a female and her offspring.

Increased meat eating also likely led to an increased division of labor between the sexes, said Aiello. The males would hunt and provide; the females — faced with more intensive motherhoods — would raise the hominid young, who were dependent longer than ape infants.

But is there evidence in the fossil record for a transition to what Aiello called “a high-quality animal-based diet”?

Briefly, yes. For one, animal bones from 2.5 million years ago showed cut marks thought to be from the earliest stone tools. And earlier species of early hominids had strong jaws and molar-like teeth; later species were more like modern humans, with weaker jaws, smaller faces, and smaller teeth.

There are other of bits of evidence pointing to meat eating by early humans, said Aiello. “My favorite are the tapeworms.”

Parasite historians — yes, there are some — say that hyenas and early humans were infected by the same type of tapeworms, which suggests they shared booty from scavenged carrion. (Such analysis is possible because of “isotopic ecology,” the study of microscopic traces of food-related isotopes in both fossils and living creatures.)

Our human ancestors were not wholly carnivores — “that would be silly,” said Aiello, who does not argue that meat-eating caused bigger brains — just that it made bigger brains possible.

If I were to meet a real evolution archaeologist, my first question I would ask is if whether without the discovery of fire, would Homo Erectus have the same level of environmental pressures to evolve into Homo Sapiens?

I agree with Setanta. Early man may have been a carnivore but he was a lousy hunter until he learned how to use such crude weapons as sharpened sticks and throwable stones. And even then he had to rely on small game that wouldn't bite back.

Is that how the sling shot came into being?

Well, there is, of course, the clear implication that the question posted in the o.p. refers specifically to man's role as a carnivore. So, while I agree with your opinion that the development of language is key to human evolution, I also see this claim as irrlevant to the question. Given the unusual brain capacity of that marvelous organ in our skulls, herbivores would, no doubt, have developed language just as readily. It has nothing to do with man as meat eater, which is what the o.p. refers to.

Eating meat led to smaller stomachs, bigger brains

Quote:

But growing brain size presented a metabolic problem. A gram of brain tissue takes 20 times more energy to grow and maintain than a gram of tissue from the kidney, heart, or liver, she said. Gut tissue is metabolically expensive too — so as brains grew gut sizes shrank.

It’s likely that meat eating “made it possible for humans to evolve a larger brain size,” said Aiello. Early human ancestors probably consumed more animal foods — termites and small mammals – than the 2 percent of carnivorous caloric intake associated with chimpanzees.

The social implications of increased meat eating were interesting, said Aiellio. In most primates, there’s no food sharing between females and offspring, she said. But the difficulty of getting meat led to cooperative food sharing among early humans, strengthening the bond between a female and her offspring.

Increased meat eating also likely led to an increased division of labor between the sexes, said Aiello. The males would hunt and provide; the females — faced with more intensive motherhoods — would raise the hominid young, who were dependent longer than ape infants.

But is there evidence in the fossil record for a transition to what Aiello called “a high-quality animal-based diet”?

Briefly, yes. For one, animal bones from 2.5 million years ago showed cut marks thought to be from the earliest stone tools. And earlier species of early hominids had strong jaws and molar-like teeth; later species were more like modern humans, with weaker jaws, smaller faces, and smaller teeth.

There are other of bits of evidence pointing to meat eating by early humans, said Aiello. “My favorite are the tapeworms.”

Parasite historians — yes, there are some — say that hyenas and early humans were infected by the same type of tapeworms, which suggests they shared booty from scavenged carrion. (Such analysis is possible because of “isotopic ecology,” the study of microscopic traces of food-related isotopes in both fossils and living creatures.)

Our human ancestors were not wholly carnivores — “that would be silly,” said Aiello, who does not argue that meat-eating caused bigger brains — just that it made bigger brains possible.

Limited language abilities were present in Homo erectus, but Homo Sapiens definitely had more language control and versatility in creating and placing meaning on symbols (thus the development of a higher level of language), so I think language and larger brains are as much an inseparable part of humanity, which is in a way connected to a diet entailing meat.

This makes me wonder if whether early language or the discovery fire helped more to circumstantially find better "food sources and the social changes they engendered accelerated our human ancestors toward civilization." It may have been both, I would guess.