Why do some people have straight hair, while others have wavy hair, or curly hair ?
Variation in evolution is caused by genetic mutation. Mutation doesn’t mean people start looking like comic book creatures, it’s as simple as genes making small errors as they copy information from one generation to the next. These mutations cause differences. Natural selection says that those mutations that are beneficial and help promote survival will tend to be preferred over those that don’t. So if you lived in a region where being physically large is a benefit, women will choose to mate with men who are large and so carry on those genes to their children. But what about mutations that are irrelevant to survival? Hair color and texture is mostly irrelevant to evolution, which is why you see all the human variation today. This means that although our earliest ancestors had thick, curly hair, for probably complex reasons having to do with environment (such hair retains moisture and heat better than straight thin hair), as we developed clothing, shelter, and changed our environments,
