Our body is made up of about 640 muscles. Or 850 — no one really knows👐🏻 That's all because the human body is extremely inconsistent, if we can put it that way. Many muscles are rudimentary — a "legacy" of evolution that the body no longer needs. That's why not everyone has them. An example is the long palm muscle — it was once used by our monkey ancestors to release claws. Some people might have it on both hands, others have it on one hand, and about 15 percent of people lack it.