Biopsychology: Nature vs Nurture?

[Todd]

I would say that this is a flawed argument based on one major fact: It is not the acquired traits (physiological ones, such as a lean body or large pectoral muscles, or an obese body) that is passed on, but rather then inherited genetics (ability to have a lean body, large pectoral muscles or an obese body). Thus Natural Selection, should not be oversimplified and viewed at the individual level as the 'survival of the fittest' , but rather a long process that favors subsections of a species with superior inherited traits (or mutated genes for that matter); allowing over time, differentiation of this sub sect.

When this is considered your argument becomes invalid. You agree to this in your premise:

it's been found that many earlier Homo sapiens have extremely lean and fit bodies due to their diet and lifestyle. Much like how many of you have stated, proper eating habits and lifestyle, supplemented by knowledge of bodily processes, can certainly counteract many (not all) biological predispositions.

You are agreeing that diet and lifestyle affect physiology, and that genetics (biological predispositions), play little role in determining body composition.