Tag Archives: Founder effects

The initial native Americans were quite inbred

From Science vol. 365 pp. 138, eaat 5447 pp.  1 —> 9 ’19  12 July ‘19

“Genetic studies of contemporary Indigenous people and ancient individuals from Asia and the Americas reveal an outline of the ancestry of the first humans to settle the Americas, providing age estimates for the timing of population contact, divergence, and migration. Studies of contemporary mitochondrial DNA (mtDNA) and Y-chromosome DNA lineages gave the first genetic insights into Indigenous American population history (6). These studies demonstrated that the ancestors of all contemporary Indigenous people had descended from only five maternal lineages (haplogroups A, B, C, D, and X) and two paternal lineages (haplogroups C and Q). These lineages also showed that the founding population came from Asia and experienced a severe genetic bottleneck, in which a small number of people with limited genetic diversity gave rise to all Indigenous people who occupied the continent before European arrival.”

Interesting that the authors of the papers discussed below didn’t know this (or weren’t telling) when I wrote them last December asking if there was limited genetic diversity in the ancestors of today’s native Americans (or Indians as they called themselves when we lived in Montana in the 70s and 80s).

 

Usually when I eMail the author(s) of a paper or a math book with a question or a comment I get a quick response.  My cynical wife says thing this is because mathematicians don’t have much to do.  Not so in this case. Hence the hopefully attention getting title of this post.

I refer to the following papers [ Cell vol. 175 pp. 1173 – 1174, 1185 – 1197 ’18 ]  Nature vol. 563 pp. 303 – 304 ’18,Science vol. 362 pp. 1128 eaav2621  1 –> 11 ’18 ] I’ve sent a bunch letters to the authors and have heard nothing back in a week.

So what is all this about?  It’s about population bottlenecks and founder effects in the ancestors of what are now called ‘native Americans’ — although while living in Montana from ’72 – ’87, if you called an Indian, a Native American, you would have received some strange looks.

I am not a population geneticist, so I wonder just how many people made it over the Bering land bridge during the last ice age, and just how genetically diverse they were.  Northern Siberia today is a rather forbidding place, and I doubt that hordes of genetically different people lived here.  I’m not sure how long the land bridge was open and how many people crossed it.

So modern native Americans may be quite genetically homogeneous.  How to tell?  This is where the papers come in.  They sequenced genomes from a variety of locations in the western hemisphere, all dying over a thousand years ago (before the Europeans came and interbred with them).  It seems that they have around 100 such genomes.

I wrote to ask how similar these genomes are.  No response.  Is it because the answer might be politically incorrect?

I don’t think the question is idiotic.  Possibly we don’t have enough genomes to make a sensible statement, but if they’re all really close (however defined) we could say something.

Anybody out there have any thoughts (or even better)  knowledge about these matters?

Were the initial native Americans inbred?

Addendum 16 July ’19   Yes they were quite inbred

From Science vol. 365 pp. 138, eaat 5447 pp.  1 —> 9 ’19  12 July ‘19
This is a direct quote

“Genetic studies of contemporary Indigenous people and ancient individuals from Asia and the Americas reveal an outline of the ancestry of the first humans to settle the Americas, providing age estimates for the timing of population contact, divergence, and migration. Studies of contemporary mitochondrial DNA (mtDNA) and Y-chromosome DNA lineages gave the first genetic insights into Indigenous American population history (6). These studies demonstrated that the ancestors of all contemporary Indigenous people had descended from only five maternal lineages (haplogroups A, B, C, D, and X) and two paternal lineages (haplogroups C and Q). These lineages also showed that the founding population came from Asia and experienced a severe genetic bottleneck, in which a small number of people with limited genetic diversity gave rise to all Indigenous people who occupied the continent before European arrival.”

Interesting that the authors of the papers below didn’t know this.

 

 

Usually when I eMail the author(s) of a paper or a math book with a question or a comment I get a quick response.  My cynical wife says thing this is because mathematicians don’t have much to do.  Not so in this case. Hence the hopefully attention getting title of this post.

I refer to the following papers [ Cell vol. 175 pp. 1173 – 1174, 1185 – 1197 ’18 ]  Nature vol. 563 pp. 303 – 304 ’18,Science vol. 362 pp. 1128 eaav2621  1 –> 11 ’18 ] I’ve sent a bunch letters to the authors and have heard nothing back in a week.

So what is all this about?  It’s about population bottlenecks and founder effects in the ancestors of what are now called ‘native Americans’ — although while living in Montana from ’72 – ’87, if you called an Indian, a Native American, you would have received some strange looks.

I am not a population geneticist, so I wonder just how many people made it over the Bering land bridge during the last ice age, and just how genetically diverse they were.  Northern Siberia today is a rather forbidding place, and I doubt that hordes of genetically different people lived here.  I’m not sure how long the land bridge was open and how many people crossed it.

So modern native Americans may be quite genetically homogeneous.  How to tell?  This is where the papers come in.  They sequenced genomes from a variety of locations in the western hemisphere, all dying over a thousand years ago (before the Europeans came and interbred with them).  It seems that they have around 100 such genomes.

I wrote to ask how similar these genomes are.  No response.  Is it because the answer might be politically incorrect?

I don’t think the question is idiotic.  Possibly we don’t have enough genomes to make a sensible statement, but if they’re all really close (however defined) we could say something.

Anybody out there have any thoughts (or even better)  knowledge about these matters?