Why did natural selection give humans opposable thumbs?

Answer 1

fry3006 and novangelis are correct. All apes have opposable thumbs ... as do the old-world monkeys (African and Asian monkeys). New-world monkeys (Central and South American monkeys) for the most part do not.

(Incidentally, three-color vision also follows the same pattern. Both of these are evidence not only that humans and old-world primates follow the same genetic line, but that this genetic line split between old-world and new-world primates at about the same time as continental drift separated the African and South American continents.)

Incidentally, we also have some vestiges of having opposable thumbs on our feet too. You will notice that your big toe, like your thumb, only has two bones (two knuckles), rather than three as your other toes and fingers have. The big toe is also much bigger, fatter, stronger, and better coordinated than the other toes (you can wiggle or lift it independently, which is harder to do with the other toes). There is even a long, thin muscle, called the plantaris muscle (google it), that extends from your big toe across the flat of your foot, and right up the calf, that has no function in humans ... but in other apes is what allows grasping with the feet. Neat huh?

But as for your question, opposable thumbs were just some mutation in these earlier primates that provided advantages in an arboreal (tree-dwelling) environment.

Incidentally (OK, this is the last one), for those who find the idea of such a huge mutation unbelievable, I recently found out that my polydactyl cat (extra toes on the front paws) is a rather common mutation in cats that occasionally leads to an opposable thumb. It is not quite as useful to a cat as it is to tree-dwelling monkeys, or they might start becoming more frequent, and cats would eventually learn the skills of holding spears and typing (they would finally be able to use the space bar) and then cats would rule the world.

Answer 2

natural selection give humans opposable thumbs

Answer 3

most people misinterpret the concept of natural selection. ask yourself this question: how would you defend yourself against a lion without a weapon?

you wouldnt and youd die, however if a random mutation that lead to opposable thumbs occured it would invariably lead to a better survival rate because you could pick up a stick and make a spear...thats the gist of natural selection...same thing goes with catching food

mutations that lead to a higher survival rate usually stick around

Answer 4

Congratulations on excellent labeling. "Innies" vs. "outies", now why haven't I thought of that. Maybe it's because my own research blinded me to the obvious. You see, I as well have spent most of my life on the beaches of the world, collecting quantum scientific data on the elusive sandal wearing hammertoe. This is not to be confused with the most recent research published in the Journal of Amalgamated Modern Irregularities (JAMI). Side note: Topographic Organization of Eskimos (TOE) has coincidently made an unlikely last minute bid last week, and have secured the majority of shares to form a new intercontinental organization TOE-JAMI. Where was I...? Ah yes, camel toes. I like them!

Answer 5

It was the best mutation. It isn't as if natural selection makes decisions about what feature to give to what animal.

Answer 6

The opposable thumb preceded humans. It can be traced back to the progenitor of all the primates which used grasping fingers for tree climbing.

Answer 7

because they knew the twist off caps would soon be available on beer bottles.

Answer 8

to make us the most successful species like...ever!

Answer 9

didn't it give it to simians too? i guess for grabbing tree branches