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

The trend toward decreasing larynx size in adult females and increasing larynx size in adult males suggests that sexual dimorphism was developing over time in these species. This is because the development of different physical characteristics in males and females is a common feature of sexual dimorphism. It is likely that this trend was driven by natural selection, as it would have provided selective advantages in terms of mate attraction, competition for mates, and resource acquisition.

Adult Male Humans Generally Have Deeper Voices Than Do Adult