>>13940915You're thinking about evolution the wrong way. It's not suspicious that lactase persistence shows up in pastoral societies because it didn't only mutate there. Mutations ARE random ajd constant, what makes a mutation spread in a population is that the environment changes in such a way that a specific mutation is suddenly an advantage.
Consider the situation with the increase in tuskless elephants. A mutation which causes an elephant to be born without tusks naturally occurs at a low frequency. If you're an elephant with this mutation in an historical environment you are fucked.
The lack of tusks renders you unable to compete with other individuals, makes you worse at defending against predators ect ect... as a result you're unlikely to pass on the gene and the number of elephants born tuskless will stay at the background mutation rate.
Now introduce a predator that can kill elephants from hundreds of meters away, can travel at speeds of 100+ km/h, has an insatiable hunger for elephants and EXCLUSIVELY targets elephants with tusks. Suddenly, being tuskless happens to protect you from the most pressing threat on your species and as a result a tuskless individual will be at a slight advantage over it's peers and more likely to pass on the tuskless gene. The same process likely occured with lactase persistence. In a society with milk and cheese, persistence is a HUGE caloric advantage.
