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 ________.

Question

Quizplus · Accepted Answer

The trend towards decreasing larynx size in adult females and increasing larynx size in adult males suggests that sexual dimorphism was evolving over time in these species. This is because sexual dimorphism refers to the differences in traits between males and females of the same species, and the trend towards different larynx sizes is a clear example of this. Option B is incorrect because there is no evidence in the scenario provided to suggest that intrasexual selection occurred in both species. Option C is incorrect because the trend towards different larynx sizes does not suggest stabilising selection. Option D is incorrect because there is no information in the scenario to suggest that selection was acting more directly upon genotype than phenotype.

Adult Male Humans Generally Have Deeper Voices Than Do Adult