Why do human beings have heads?

Question

I was wondering about humans in particular, but most mammals have their sense organs and brains all located in a head. From an evolutionary standpoint it seems unwise to cluster so much vital anatomy together like that, but I'm sure there's a sound, scientific reason for it. I just... can't find one :\

To clarify: It seems like it would make more sense for the brain and sense organs to all be located in the abdomen, rather than in a limb like the head which can be easily severed.

Answer 1

This goes right back to a basic body plan for most animals going throughout evolution. (A lot of this I got from Richard Dawkins, Ancestor's Tale.)

The basic body plan for most animals is a tube, with one end for feeding, and the other for excreting. It then becomes useful to have all the senses at the feeding end, as the senses are helpful for finding food (and not needed at all for excreting).

And then, as the nervous system gets more sophisticated, it becomes convenient to have the ganglia, and later the brain, near the main sensory organs. This reduces the length of vital nerves from the sensory organs to the brain. (E.g., if your brain was in the most protected part of your body, your abdomen, then think of how long the optic nerves would have to be from your eyes. Not only does this cause a delay in signal transmission, but it increases the odds of damage to the optic nerve.)

Fast forward a couple of billion years, and this tube body plan hasn't changed much. Sensory organ snear the feeding end, and brain near the sensory organs. Humans are no different, except that they stand upright.

But even then, it is advantageous to have our sensory organs perched as high up as possible, and again, to have the brain as close to these sense organs as possible in order to shorten the distance that sensory impulses have to travel.

Answer 2

Easy, the highest point in the body so that the connection from the major sensory organs, eyes, and ears have the shortest contact time.

Answer 3

since the brain can not be put into your legs, since your eyes can not be placed in your hands, there comes the need of some space....at the top of your body, that is safe to some extent....so the creator created an empty almost rounded space called head to put those unnecessary things like eyes, mouth, nose, hair, and most importantly the BRAIN....
Got it....???

Answer 4

Very clever question .Maybe this type survived in the earth conditions.I wish I could see what happens in other living planets,and if this is a general rule

Answer 5

if u didnt hav a head u'd a. have no "attractive" features, brain (tho by asking this question u have proved u have no brain (jokes))
also with no head u would have no eyes or stuff, so ya anyway
check ya
W

Answer 6

For the awesome haircuts we can get.

Answer 7

To make sex more interesting.