This is an upper bound for the number required to prevent extinction. Smaller groups would suffer more seriously from inbreeding, especially since our society’s genome has a lot more deleterious mutations in it than a hunter gatherer one. But quite badly inbred humans could still survive, breed up to more survivable numbers and gradually fix their genome by natural selection. The real number is probably a good deal lower.
This is an upper bound for the number required to prevent extinction. Smaller groups would suffer more seriously from inbreeding, especially since our society’s genome has a lot more deleterious mutations in it than a hunter gatherer one. But quite badly inbred humans could still survive, breed up to more survivable numbers and gradually fix their genome by natural selection. The real number is probably a good deal lower.