The Statement

question 18

Multiple Choice

The statement.__________, best summarizes the relationship between the birth canal and brain size during the course of hominin evolution.

• A)"natural selection has favored a tendency toward decreased brain size and a reduction in the size of the pelvic opening throughout hominin evolution"
• B)"brain size has become more important than bipedalism over the course of hominin evolution, and the pelvic opening has continually expanded to compensate for larger brains"
• C)"natural selection has struck a balance between the structural demands of upright posture in bipedalism, which limits the expansion of the pelvic opening, and the tendency toward increased brain size"
• D)"the birth canal has become narrower throughout hominin evolution, even as brain size has continued to increase"
• E)"the human pelvic opening has continually expanded to allow for increased brain size, and the upright posture of bipedalism has been unaffected by these structural changes"

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Definitions:

Primary Sex Characteristic

The physical features, including genitalia, that are present at birth and involved in reproduction.

Lifespan

Pertains to the length of time an individual lives, from birth to death.

Senescence

The natural physical decline brought about by increasing age.

Physical Decline

The gradual reduction in physical abilities and functions as part of the aging process or due to illness.