What is the Impact of Early Human Migrations on Genetic Diversity?

[BillTre]

Two new papers have come out about the genetic make-up of early Americans.
This has helped to clarify the relationships among early American residents, revealing different waves of migration.
Here are two popular articles on these findings from;
NY Times
Science magazine

 

[fresh_42]

I have seen on TV that some paleoanthropologists do not completely rule out that there might have been a second immigration path from the Atlantic. IIRC the evidence was, that the way the Clovis manufactured flint was similar to European finds of the same time period. I'm curious whether this possibility will be ruled out or even be supported by future genetic analysis.

 

[DaveC426913]

Interestingly, there was an article recently that used genetics to show that all humans today originated from a single migration out of Africa through Mesopotamia and the Arabian Peninsula. Of course, that was long before the migration to the New World.

 

[fresh_42]

Interestingly, there was an article recently that used genetics to show that all humans today originated from a single migration out of Africa through Mesopotamia and the Arabian Peninsula. Of course, that was long before the migration to the New World.

I've heard about it, too. We seemingly went through at least one genetic bottleneck of - what I have heard - a few hundred people and about 15 different families or so. Would be interesting to know something about the least number of individuals needed to save a species. Maybe the interbreed with other human species was simply a necessity.

 

[DaveC426913]

...at least one genetic bottleneck of - what I have heard - a few hundred people and about 15 different families or so.

I did not know it was this small.

Would be interesting to know something about the least number of individuals needed to save a species. Maybe the interbreed with other human species was simply a necessity.

An active area of research. There was speculation a few years ago that North Atlantic Cod may be effectively extinct because they won;t breed in populations smaller than millions.*
* may be an entirely apocryphal artifact of my aging brain

 

[fresh_42]

I did not know it was this small.

I wished I knew a reliable source. It was a couple of years ago as biogenetics started to investigate mitochondrial DNA in more detail. However, it's possible that it was based on an article of a single scientist and does not necessarily reflect mainstream knowledge.

 

[BillTre]

Interestingly, there was an article recently that used genetics to show that all humans today originated from a single migration out of Africa through Mesopotamia and the Arabian Peninsula. Of course, that was long before the migration to the New World.

Of course, there are those who never left Africa to consider, so not all humans are descended from those that migrated out.
In addition, different migrations of H. sapiens humans encountered and interbred with Neanderthals or Denisovans resulting in different mixes of these different genomes and therefore creating more genetic diversity.

I've heard about it, too. We seemingly went through at least one genetic bottleneck of - what I have heard - a few hundred people and about 15 different families or so.

A few hundred individuals seems small to me (that would be as small a breeding population as in some inbred fish genetic lines I had),
unless that happened along time ago so the background levels of mutation could gradually restore genetic diversity,

Maybe the interbreed with other human species was simply a necessity.

or unless hybridizing with a second population could quickly restore diversity levels.