Why did humans evolve difference noses from chimps?

[yodachoda87]

So, as you know, we humans share a close common ancestor with the common chimpanzee. I have a few questions about our evolution.

1. In the past, anyone with a mutation that allocated resources to a larger brain size rather than hair on the fact and arms was likely favored by natural selection AFTER they started using fire. Why is it that hair growing from the top of the head remained? I'm guessing this has something to do with hair on the head controlling temperature in a different way than hair on the body...

2. Why are our noses more pointed than chimpanzee noses? I have a hard time thinking of why natural selection might favor pointed noses. Could this be purely sexual selection?