What is the evolutionary purpose of baldness?

That's like asking what the evolutionary purpose is of arthritis. Not everything that happens has a benefit, the theory doesn't even state that, in fact evolution (mutation) often causes neutral and undesirable traits. Baldness can be caused by stress, exposure to certain chemicals, and by genetic traits. But you can't deny that organisms evolve, and you can't deny that baldness can be passed down genetically, those are two things we know, so there's really non point in asking why if all you're trying to do is discredit evolution. If you asked this is in the proper category, and you asked it with a different tone then it would be a legitimate question.

On the flip side, why would God create baldness? When you point at what's wrong with us, you're only arguing against an intelligent designer. When considering how flawed and convoluted life really is, which explanation makes more sense: the accumulation of random mutations in response to the environment over long periods of time... or an intelligent being that created the universe with us in mind? If I was God I would have designed much better organisms, or designed a much more efficient process than evolution.

EDIT: With all that said, there could actually be some evolutionary reason. I doubt it, but that's what the internet is for. Either way, I'm sure baldness is very well explained, you could find a better answer much easier than on Y!A.

If anything, balding in males would be poor genetically considering that the hair protects the solar from warmth and bloodless, and the pinnacle is the essential section to protect for the period of extreme climate stipulations. Despite the fact that, since of human civilization, a easy hat can replace hair, and as a consequence, the baldness gene wouldn't get eradicated.

Not every trait held by any organism fits into some grand scheme of evolutionary fitness. Things just are as they are, and environmental influences affect which traits get selected for the next generation. Obviously some traits will be beneficial and others disadvantageous. It's a battle of relative fitness, not absolute fitness; competition with one's peers, not some perfect, insurmountably tough biological being.

All sexual species recognize signs of less vigor within its own species. For birds, it might be recognizing a sickness or a male who isn't good at hunting and thus has a dull coat.

For humans, one of those traits is baldness. It doesn't have a purpose, but it's a sign of a person likely to be sexually less vigorous than someone who isn't balding.

Some traits arise despite a lack of purpose or benefit, but because they are generally benign they aren't filtered out by natural selection.

I don't think evolution or adaptations occur nearing the end of life, it is just that your body cannot function as well as it did in its prime, when you were younger, and can no longer provide the necessary nutrients to grow long, healthy hair, nails etc.

Men who are bald are more likely to be found by aliens who see the reflection in space. They therefore are the saviours of mankind.

Evolution doesn't always work in favor of the species, it can be counter-intuitive for certain things to exist, namely certain vestigial organs of the human body....

Nature doesn't give a crap about someone's hair - especially when the hair isn't a factor in whether or not men can reproduce.

I'll guess- that it's a byproduct of extra testosterone, which breeds more