The real evolution nightmare: hairs

I was sitting on the can the other day, when it occurred to me how the flushing toilet was one of human's best technological achievements. In fact I believe it might be one of these key things that jump-started civilization, like agriculture, writing or the wheel. Think about it, without flushing toilets the early human had to venture far outside of the cave, where he could be preyed upon, or if he chose to be lazy, put his entire clan at risk of infections from an unsanitary dwelling. The first remains of flushable toilets date from 2600BC. In 1886 the first jet-flush toilet was invented in England, and was later improved in the US by using IR sensors in the 1970's to create the first self-flushing toilet. This for sure must be the pinnacle of human waste disposal you might think, I don't have to go outside at -20ºC, I don't need to put the seat up (unless you live under female tyranny), I don't need to flush. Yet there is an ultimate limitation, here I am in the 21st century, wiping my own butt with some archaic scroll made from dead trees. On top of it, it is very inefficient and unsanitary because the damn shit sticks to my butt hairs. So I wipe and wipe, and spread the bacterial goodness around. Apparently in North America, we haven't discovered the bidet. The Europeans must have invented it after we left and forgot to tell us about this technological marvel. In fact, while most countries may be behind our times with our self-flushing toilets, they are way ahead of us in the butt washing department.

So the question popped in my head, why do we even have butt hairs. I mean we lost most of our body hairs, they're pretty vestigial at this point, so why keep butt hairs. Once upon a time we were covered in body hairs, it kept us warm, protected us from the sun and bugs but then we started losing it. Some theories propose that it is sexual selection, females preferred males with less hairs. But we kept the one on our head, I guess the females liked those, and they were the only ones needed for sun protection, since we now walked upright. We also kept those in the pubic area and under the arms, maybe to spread our pheromones around. We kept some around our eyes and in our nose to protect from dust. But why keep those around the butt hole. Were the females preferring man with butt-hairs. If anything it is displeasing for both parties. I mean, I don't think they're there to keep the dust from going in, or to protect from the sun, since it doesn't shine there as they say. Perhaps to spread our pheromones around, but I doubt that kind of odour is very attractive to females. It is an evolutionary mystery.

In fact no one knows when hairs evolved in mammals in the first place, since they seemed to come all at once. Unlike feathers coming from scales, there is no obvious previous structure from which it evolved. They rose independently in insects and other animals, but only once in mammals. The only mammals which lack fur are the pigs, whales, elephants, humans, mole rats and walruses. In these only small fine hairs are present. In fact the average human has more hairs than a chimpanzee, they are just harder to see. So if humans are still evolving, I know one thing we could improve on...