Learn some fun and interesting facts about the human body on this Moment of Science.
After all, for the basic body plan to change, not only do you need a random genetic mutation that results in a sixth finger, but that mutation must also provide an evolutionary advantage when it comes to reproduction.
As a boy goes through adolescence, his secondary sex characteristics develop. One of these characteristics is the rapid growth of the larynx and vocal cords. A boy’s voice deepens as his larynx develops because the bigger the vocal cords, the deeper the voice.