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 ________.

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Quizplus · Accepted Answer

A trend towards sexual dimorphism in larynx size suggests that there was evolutionary pressure for males and females to develop different traits related to vocalization, potentially for mating or communication purposes. This is supported by the fact that adult male humans generally have deeper voices, which can be attributed to increased levels of testosterone during development. This trend towards sexual dimorphism implies that selection was acting on phenotype rather than just genotype, as the physical traits of larynx size were evolving differently across genders in response to environmental pressures.

Adult Male Humans Generally Have Deeper Voices Than Do Adult