Throughout the evolution of humans, we have consistently changed to a novel environment which no longer matches our environment of evolutionary adaptiveness. As a result, humans have become vulnerable to different conditions we were not vulnerable to before. For humans, a majority of physiological changes including increased brain size occurred during the Paleolithic Era which lasted for 2 million years (Easton 67). Because a majority of the evolutionary traits which defines us as a species occurred during this time, our diet played a key role in giving us the energy and nutrients that enabled these changes. The human diet is something that has changed considerably from the environment of evolutionary adaptiveness and we are now facing a slew of health consequences as a result. One of major heath consequences is obesity, which often leads to the other conditions are at risk of developing. There are two aspects of the the human diet which varies from the environment of evolutionary adaptiveness: the eating patterns of humans and the composition of the diet. With both these factors different in the novel environment of humans, humans are now vulnerable to a variety of detrimental health conditions.
Comments
Rephrase
You could change this sentence 'Because a majority of the evolutionary traits which defines us as a species occurred during this time, our diet played a key role in giving us the energy and nutrients that enabled these changes' to 'Our diet gave us the energy and nutrients to support evolutionary traits, which define us as a species today'. I feel this helps the flow o your paragraph.
Rephrase
You could change this sentence 'Because a majority of the evolutionary traits which defines us as a species occurred during this time, our diet played a key role in giving us the energy and nutrients that enabled these changes' to 'Our diet gave us the energy and nutrients to support evolutionary traits, which define us as a species today'. I feel this helps the flow o your paragraph.
Wording
'With both these factors different' should likely be changed to something along the lines of 'With these different factors'