Why we are not naked even in the womb

The nearly naked ape

Desmond Morris, the great English biologist, wrote in THE NAKED APE (1967) that of the 193 different species of primates, only one is naked: Humans. Morris meant that all other primates are covered in body hair. Ironically, we are also the only primates that cover-up our natural nakedness. Actually, in a sense Morris is wrong. We are not entirely naked. We do have at least some body hair although not nearly as much as our non-human primate cousins.

From birth we have hair on our head, eyebrows, and eyelashes. At puberty we develop hair elsewhere on our bodies. Throughout life some of us lose hair in some places and gain it in others. Some places remain with hair. And for some of us, we grow so much hair that we could truly be called "hairy" - almost in the gorilla sense.

What most of us don’t know is that, not only are we not entirely hairless as adults, we are not even naked in the womb. About four months into a normal nine-month pregnancy, when the fetus is about 5.3 inches (135 mm) long and weighs about 6 ounces (170 g), it grows a moustache! Fine hair forms on the upper lip. Gradually, over the next month or so, this fine hair spreads to eventually cover the entire body! The unborn baby remains completely hairy for many weeks.

This soft, hairy coat is called lanugo. The word is from the Latin lan and means “wooly down”. This hair suit is shed before or soon after birth. Each hair of the lanugo is shed one by one and is then swallowed by the baby. The tiny hairs join mucus, bile, and other products to form a black substance called meconium. Just after birth, this meconium is excreted by the newborn in its first bowel movement. One must admit that this is a rather interesting way of ridding ourselves of our first unwanted clothes!

After we shed our lanugo, most of us are born with hair only on our head, eyebrows, and eyelashes. This fine, non-pigmented hair of infancy is called vellus. “Vellus” is from Latin and means “fleece”. As we mature, the body replaces vellus with coarser, pigmented hair called terminal hair. Terminal hair is our true adult body hair - our only natural body clothes we carry through life. Nature leaves us almost naked. Our hair is not nearly enough to keep us warm in all weather so we wear artificial clothes. Thus we are the nearly naked ape.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

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