What is introgression?

Introgression is when two groups mix and share traits over time, like how friends borrow toys from each other.

Imagine you have two neighborhoods: one full of kids who all love basketball, and another where everyone loves soccer. One day, some kids from the basketball neighborhood start playing soccer with the soccer kids. They enjoy it so much that they keep playing together. Soon, some of them even bring their basketballs to soccer games, and others bring their soccer balls to basketball courts. Over time, more and more kids from both neighborhoods start mixing up their favorite sports, and maybe even some of them end up liking both!

This is like introgression in action: when two groups mix, they share traits (like love for a sport), and those traits can spread through the whole group.

Let’s say a few basketball-loving kids start playing soccer regularly. They might learn new moves, and their friends notice how good they are at soccer now. Soon, some of them even start coaching others in soccer, and then the basketball love starts to fade for some of them.

In this way, traits from one group can slowly spread into another, just like kids sharing toys or sports across neighborhoods.