if procreating with close relatives causes dangerous mutations and increased risks of disease, how did isolated groups of humans deal with it?

Question

if procreating with close relatives causes dangerous mutations and increased risks of disease, how did isolated groups of humans deal with it?

In: 562

Answer 1

Inbreeding doesn’t cause mutations, it just makes it easier for those mutations to express themselves.

Simplified explanation:

Normally you get one copy of your genes from your father and another copy from your mother.

If one of those two copies contains an error your still have the other one.

If your mother and your father are sibling and inherited the faulty copy from the same parent. You may get the broken plan from both your parents and no clean unbroken copy.

In a group of closely related humans that keep having children with each other birth defects and genetic diseases thus become more common.

Of course populations can still survive with this handicap. Individuals not so much, but the group as a whole yes.

The ones with the biggest issues simply die and do not get to have children of their own.

One exception are stuff like royal bloodlines where they kept marrying each other and kept getting worse and worse birth defects, that a peasant would simply have died in childhood with but a noble had the resources to survive to have more inbred kids of their own.