SAT Subject Biology Practice Question 445: Answer and Explanation
Homo sapiens (modern human)
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.