![]() ![]() Way back when, maybe we all had tails, and they provided some important function for us, perhaps to help us balance.Some other traits that could possibly be human atavisms are webbed fingers and toes, extra fingers and toes, hiccups and large canines. All vertebrates have the ability to make a tail, and guess what? Humans are vertebrates. But the true human tail has nerves and muscles and sometimes even cartilage or vertebrae, although there seems to be some scientific debate about this last point. The pseudo-tail doesn't have any bones or cartilage - it's skin and fat. There are two kinds of human tails, however: the pseudo-tail and the much rarer, true human tail. ![]() It's not just a gag to pull in a Farrelly brothers movie - it really happens. The atavism you've probably heard of most often? The human tail. In order for the trait to be an atavism, an organism's parents can't have the trait, and neither can recent ancestors. Their wings are vestigial - they're used for a purpose, but not the purpose for which they may have originally served.Ītavisms are traits of distant ancestors that reappear in the modern day. Ostriches use their wings for other purposes, like balance, but their wings can't function as wings. Think of the ostrich: It has wings, but it can't fly. Vestigial structures are body parts that survive as degenerate, imperfect versions of what they should be. What's the difference between atavisms and vestigial structures? They're actually pretty close. If it is an avatism, it's not from the animals we point to when we talk about evolution, like chimps. So hypertrichosis, a condition in which excessive amounts of hair cover the body, isn't an atavism - unless our ancestors were werewolves. Ape faces are clear of hair, as Michael Le Page notes in his New Scientist article on atavisms. Is the world's hairiest man really a throwback to our simian ancestors? Not quite. Newspapers call conditions like this and others atavisms. Perhaps you've heard of the world's hairiest man. ![]()
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