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Why Do We Have 10 Fingers And 10 Toes?

Why not 5 or 15? Why is 10 the magic number when it comes to fingers and toes?


Photo: psycherika (Flickr)

Humans have 10 fingers and 10 toes for a reason. Scientists are still puzzled why 10 is the magic number.

You may be wondering why we evolved to have ten fingers and ten toes. Why not eight, or only four?

The truth is that we don’t really know why ten became the magic number for fingers and toes.

Several Variations

We do know that fingers and toes, or claws come in several variations. Some mammals have five digits on each hand and foot. Others have fewer.

For example, horses have only one hoof per foot. And pigs and camels are cloven hoofed, meaning that they have two toes per foot. Squirrels have four toes on each front foot, and five each on the back feet.

More Fingers And Toes

Scientists also know that many animals used to have more fingers and toes. Back in the day, about 400 million years ago, the first vertebrates that crawled out of the ocean commonly had seven or eight digits per hand and foot. But then, for reasons that remain a mystery, a few digits faded away and ten or fewer became the norm.

Adapting For Change

This isn’t to say that all mammalian hands and feet are the same. Some animals have digits specifically adapted for climbing. Others sport ferocious claws. And, of course, we humans boast a handy opposable thumb.

But when it comes right down to it, we still share many traits with our fellow mammals. And having ten fingers and ten toes is one we share with many of them.

  • Beth Johnson

    This isn't quite true. The “Rule of 1, 2 and 5″ says that all mammals have one bone in each upper limb, two in the lower limb and five below the wrist or ankle. This rule is never breached. Horses actually have five toes, although they have fused into a hoof. A biologist or a veterinary surgeon could point them out to you on an X ray. Certain animals need more than five digits, for instance the Giant Panda, but it still has five bones. The extra thumb is a development of its wrist.

    The pattern of bones in limbs is due to gas diffusion patterns. I believe the pattern of 1, 2 and 5 was attributed to gas diffusion by Barnes Wallace but I'm not sure.

    The other reason that we have 10 fingers is that, of course, we can count units on our fingers but once we've used all our fingers we have to carry one into the tens column and start again from zero in the units column. We would still have 10 fingers even if we had eight fingers on each hand, only then we would count 1 2 3 4 5 6 7 8 9 a b c d e f 10 11 12… like computers do.

  • Ferm Medel

    Give more lesson and additional knowledge to the viewer….

  • Doug mckinney

    Horses had five toes once upon a time. They slowly evolved to walk solely on their middle “finger.” Here is a link to a brief but accurate history of the horses’ hoof.

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