A deep curiosity is a behavior many people have (but not all). We try all kinds of things and some of them 'catch' socially. Many bird species have behaviors like this. Birds (especially things like corvidae) will pick up a new behavior in an area, and you can track the spread of the behavior radiating outward to new areas as more members of the species pick it up from each other.

The sentence "Survival of the fittest" isn't exactly true, the more accurate description would be "Survival of the fit enough". Curiosity itself is a means to explore the problem space of reality. If you're not curious then changes in your environment may leave you unable to adapt. If you're too curious then you can end up in situations where it removes members of your species faster than they can breed. Even after the point of the individual learning something new it doesn't do much for the existing members of your species. The most optimal outcome seems like some sort of cautious mimesis transfer. In the same idea as "monkey see, monkey do", there doesn't have to be a why, other than it doesn't harm the prime directive of stay alive, get more food, breed.

That is, these quartz arrowheads are a very early version of a meme.