While the human brain makes up only _____ of the bodys weight, it requires about _____ of the bodys resources when at rest.
a. .75; 8
b. 2; 15
c. 4; 25
d. 7; 30
Question 2
Why is it thought that advances such as agriculture, literacy, and urbanization have not been accompanied by additional increases in brain size?
a. The earliest Homo sapiens were as intelligent as contemporary humans.
b. Although brain size has remained constant, brain density has increased.
c. The physiological cost of a bigger brain exceeds its benefit.
d. More efficient neuronal connections account for modern human advancements.
Cerebral angiography. The four angiograms each reveal the distribution of blood vessels supplying th
The Reticular Activating System and Related Regions in the Brain Are Important Areas of Focus for D
The biped’s foot bears more weight than the quadruped’s and so the bones are stouter.
A Human Element Emerges
Neurons in the outer layers of the brain
Human embryo at successive stages of development (not to scale).