Adult male humans generally have deeper voices than do adult female humans, which is the direct result of higher levels of testosterone causing growth of the larynx. If the fossil records of apes and humans alike show a trend toward decreasing larynx size in adult females and increasing larynx size in adult males, then
A) sexual dimorphism was developing over time in these species.
B) intrasexual selection seems to have occurred.
C) stabilizing selection was occurring in these species concerning larynx size.
D) selection was acting more directly upon genotype than upon phenotype.
Male (Bull) Roosevelt Elk at Northwest Trek, Washington, USA
Amsterdam Albatross - Adult in flight, showing dark plumage typical of the species.
The pubic symphysis of the pelvis is useful for estimating age in the adult skeleton.
Comparison of (a) male and female skulls and (b) male and female pelves.
Procedures and Diagnostic Tests Related to the Female Reproductive System
Internal female reproductive organs.