SAT Subject Biology Practice Question 445: Answer and Explanation

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Question: 445

Homo sapiens (modern human)

Australopithecus afarensis

Australopithecus africanus

Pan troglodytes (modern chimpanzee)

What is the most advantageous difference between the ancestral primate skulls and the modern human skull?

A. Forward-facing eyes
B. Increased brain capacity
C. Loss of canine teeth
D. Loss of brow ridge
E. Reduction in jaw size

Correct Answer: B


B Having forward-facing eyes (choice A) was certainly an advantage as it increased visual depth perception. However, because all the skulls have forward-facing eyes, this does not represent a difference between ancient primates and modern humans. Loss of the canine teeth, loss of the brow ridge, and a reduction in jaw size (choices C, D, and E) are also apparent differences, but none is as helpful as the increased brain capacity.

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