Up to 85% of people have a vestigial muscle called the " palmaris longus."

多达85％人有种叫做“掌”退化肉。

Looking at our primate relatives, we can see that the palmaris longus is sometimes absent in those that spend more time on the land, but always present in those that spend more time in trees.

观察们灵类动物祖先，们可以发现，那些在陆地上生活更久动物有时没有掌，但是，那些在树上生活更久动物总是有掌。