A high–calorie diet providing adequate fats was a crucial requirement for the evolution of the anatomically modern hu...

SarahA on May 26, 2019

Why are a and c incorrect?

Could someone please explain why a and c are incorrect, and why e is the correct answer choice?

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Victoria on June 8, 2019

Hi @msaber,

The passage tells us that the evolution of the modern human brain began among early humans and required a high-calorie diet with adequate fats. Early humans could find food resources which supported a high-calorie diet with adequate fats abundantly and reliably in shore environments. However, the evolution of the modern human brain almost exclusively took place in savanna and woodland areas.

The question stem is asking us to select the answer choice that helps to resolve the apparent conflict presented by the passage and, therefore, is a paradox question. The passage presents us with a dietary condition necessary for the evolution of the modern human brain and tells us that this condition could abundantly and reliably be satisfied in shore environments. However, confusingly, the evolution of the brain occurred almost exclusively in areas that were not shore environments. We are looking for the answer choice which provides an explanation for why this might be so.

A is incorrect because it is irrelevant. The paradox is that the evolution of the modern human brain took place in environments outside of those which were most likely to satisfy the necessary dietary requirements for its evolution. This answer choice does not provide us with any information regarding the environments within which early humans expended their fat reserves and, therefore, is not the correct answer.

C is a tempting answer choice, however, the inclusion of one word and the omission of another make it incorrect. Nowhere in the passage does it say that the human brain evolved in prehistoric times. The passage simply tells us hat the process began among early human ancestors, but we do not know which period of history this was in. Additionally, this answer choice simply says 'resources' as opposed to 'food resources.' Even if this answer choice is attempting to refer to food resources, the fact that savanna and woodland areas were more reliable and abundant in the past says nothing about how they compare to past shore environments. Even if past savanna and woodland areas were more resource-abundant than they are today, this still could have fallen short of the dietary requirements that were satisfied by shore environments.

E is correct because it provides an adequate explanation for why the human brain may have evolved nearly exclusively in savanna and woodland areas as opposed to the resource-rich shore environments. If gathering food in shore environments required a significantly greater expenditure of calories than in other environments, this may have negated the benefits of the reliable and abundant food resources. As a condition for the evolution of the modern human brain was a high-calorie diet, it makes sense that this evolution would have largely taken place in environments where gathering food to support this diet did not also require large expenditures of calories.

Hope this is helpful! Please let us know if you have any further questions.

SarahA on June 10, 2019

You write great explanations, Victoria. I really appreciate how clearly you illustrate the proper thought process and leave no loose ends. Just a heads up the end of your explanation was cut off, it ends at “...it makes sense that this evolution would have largely taken place in environments...”. But I completely understood what you wrote. Thank you!

Victoria on June 11, 2019

Thank you so much! Happy to hear that my explanations helped you out. Your response here has also cut off the ends of a couple of your sentences, ending them with symbols and boxes... strange.

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Keep up the great work and good luck!