meat, evolution, cancer

Discussion in 'Biology & Genetics' started by w1z4rd, Nov 7, 2008.

  1. w1z4rd Valued Senior Member

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    I have being reading up a little on how meat has effected the evolution of humankind.

    I dont know how right my information is but this is how I kinda understand it.

    Basically homo separated from australopithecines 2 million years ago in Africa. One of the ideas I hear for why we walk up right is because that area in Africa underwent massive climate change. The tree`s and plants that were common in that area disappeared.. the early homos came out of the tree`s and adapted to the african savannah, Theres lot of tall grass and often few tree`s in that kinda habitat so standing up looking for danger (kinda like a meerkat) and then learning to move while standing would have being an evolution advantage.

    Less fruit and plants to eat would most likely have meant that those that adapted to eat meat had a better chance of survival. Meat would have then aided our evolution so far as body mass, intelligence and brain development.

    I was reading a WHO report on the association between a very much increased chance of cancer to excessive meat eating. I wanted to know if that is because our bodies our still evolving to process meat better? IE, in terms of waste disposal and absorbtion?
     
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  3. Fraggle Rocker Staff Member

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    Sure, but it doesn't explain why the animal we speciated away from, Pan trogolodytes (the "true" chimpanzee), was able to adapt to a much less arboreal life without undergoing all of the adaptations humans did. Even gorillas, our slightly more distant cousins, spend the majority of their time on the ground, yet they are grazers who are able to digest a whole lot of cellulose.

    I think there must have been another force at work which we haven't conclusively identified. It could be something as simple (and as difficult to prove) as adventurousness. For example, I think that was almost certainly the quality that caused Canis lupus familiaris to form a distinct population from Canis lupus lupus. The wolves who were destined to become the ancestors of dogs were just a little bit more curious, more adaptable, more comfortable in larger packs, more content to scavenge instead of hunt, less determined to be the alpha of the pack, etc., than the wolves who chose to remain in their own single-species pack. Wolves and dogs both still exist but we still don't really have any way to measure that key difference except by inference.

    The proto-chimpanzees who decided to try their luck on the savannah might simply have been the ones who liked the taste of meat better than the taste of leaves, who enjoyed hunting down frogs and rodents and wanted to try their hand at larger game, and who got a thrill out of standing a little taller than the other chimps.
    Again, I don't see persuasive evidence that there was a shortage of herbivore chow, given that the chimpanzees were and are a highly successful species.
    Most definitely the latter. Brains take an enormous amount of protein for maintenance. One of the few measurable differences between the two subspecies of Canis lupus is that dogs have smaller brains relative to their body size, having adapted to the lower-protein diet of scavenging our middens.
    No. It's because carnivory puts us at the top of the food chain. Man is now the apex predator of the entire planetary ecosystem. Pollutants concentrate in the tissues of animals that eat other animals, which is a very good reason not to eat other apex predators such as sharks, or scavengers such as catfish.

    Admittedly, in the more developed parts of the world even the scavenger flesh we eat, such as pork, is raised on a vegetarian diet. But we shoot them full of antibiotics and growth hormones, and we do the same thing to the plant tissue they eat. Add to that the herbicides and other poisons that we spray on our crops and the industrial effluent in the water table, and we're talking about chemicals that can affect our metabolism in concentrations so low that they're measured in parts per trillion.

    Our bodies are well adapted to digesting meat. There is at least one vitamin that we can ONLY get from meat, and there are other key nutrients that are difficult for us to extract from plant tissue. Remember that the only reason humans were able to defy our carnivorous nature and backslide into a vegetarian diet after the Agricultural Revolution is that we cook our food. We have completely lost the ability to digest raw cellulose, the plant tissue that much of the animal kingdom--including some of our closest cousins--rely on for calories.

    Even at that, ancient humans suffered greatly from our experiment with retro-vegetarianism. At the end of the Mesolithic Era, when humans ate primarily meat augmented by the occasional herb, nut, seed, etc., the life expectancy of an adult who managed to survive the rigors of childhood was in the low 50s. By the time of the Roman Empire, when everyone except the wealthy ate a grain-intensive diet augmented by a bit of dairy, it had plummetted to the low 20s.

    Of course this is because no one knew about vitamins and minerals, which are practically absent in grains, especially the smooth refined grains of which our ancestors became enamored. Today it is possible to build a well balanced vegetarian or even vegan diet by adding nuts, seeds and carefully selected herbs and spices, or simply chemical supplements, which ironically relies on an industrial civilization to provide, and at best is a rather expensive diet.

    Our bodies are well adapted to eating meat.
     
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  5. John99 Banned Banned

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    Not to mention other Carnivores who do well with meat.
     
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