Touch your thumb to your pinky. Can you see a long, thin muscle pop out on the inside of your wrist? If not, congratulations — you’re a mutant. You’re missing a muscle that makes it easier to swing from tree branches. Our orangutan cousins still have it, but since we generally don’t need to swing through the jungle like Tarzan, humans are evolving without it.
The absence of this muscle in about 15 percent of humans is an example of how evolution is an ongoing process. And as humans change on genetic and physiological levels, researchers are already documenting subtle changes in the makeup of our bodies.
