Read on Twitter
#CLST6 #ArchMethods
For today's #CYO2, I listened to episode 26 of The Arch&Ant podcast titled "How do geneticists study complex traits in humans? How do ancestry tests work?". The guest of this episode was geneticist Arslan Zaidi (for more, check out: http://arslanzaidi.com )
/1
For today's #CYO2, I listened to episode 26 of The Arch&Ant podcast titled "How do geneticists study complex traits in humans? How do ancestry tests work?". The guest of this episode was geneticist Arslan Zaidi (for more, check out: http://arslanzaidi.com )
/1
The focus of this enthralling conversation was complex traits and their role within human evolution. I was shocked by how the two allele process that we are taught in biology classes is an exception. Most traits are complex-are controlled by multiple genes (+1000 for height).
/2
/2
Scholars were investigating whether differences in nose shape-specifically the nasal aperture-was indicative of the geography that individuals belonged to.
This immediately reminded me of the reading we had on Bioarcheology by Renfrew and Bahn.
/3
This immediately reminded me of the reading we had on Bioarcheology by Renfrew and Bahn.
/3
Just like how teeth could inform archeologists of age, maybe nose could inform them of geography (Bahn 372). The premise behind this study was that noses need to make the air warmer and more humid before it enters the lungs and that humidity&temperature differ between regions.
/4
/4
So the nose geometries of people living in geographies with different temperatures and humidity could've been different.
But as Zaidi points out, the challenge was that it is difficult to disentangle genetic factors from environmental conditions (sunlight, nutrition, etc.)
/5
But as Zaidi points out, the challenge was that it is difficult to disentangle genetic factors from environmental conditions (sunlight, nutrition, etc.)
/5
And also random factors such as genetic drift-the accumulation of certain traits in populations according to their random splitting-might have come into play.
Luckily, for nose shape it wasn't possible to account for the differences with the idea of genetic drift.
/6
Luckily, for nose shape it wasn't possible to account for the differences with the idea of genetic drift.
/6
After the collection of genetic data, 3D nose photographs and demographic data from 4000 samples, scientists found that the geographic distribution of the width of the nostrils was statistically correlated with the temperature and absolute humidity of respective regions.
/7
/7
As it always is in statistics-correlation does not indicate causation. Yet, this was an incredible finding that could be utilized by archeology.
And I see its potential utilization similar to that of the genomic analysis of an Aznick boy-reconstruction of theories (Bahn 474).
/8
And I see its potential utilization similar to that of the genomic analysis of an Aznick boy-reconstruction of theories (Bahn 474).
/8
It is incredible to see how big of a role genetics plays in archeology.
A critical example of that, in my opinion, was the reinforcement of the "Out of Africa" theory by an mtDNA analysis mentioned in the Bahn reading we had done for class (Bahn 470).
/9
A critical example of that, in my opinion, was the reinforcement of the "Out of Africa" theory by an mtDNA analysis mentioned in the Bahn reading we had done for class (Bahn 470).
/9
In addition to elucidating certain issues, however, the commercialization of genetics can also lead to misconceptions. This was the second major topic that was talked about in the podcast. Ancestry tests...
In the podcast, Zaidi talks about how complex ancestry actually is.
/10
In the podcast, Zaidi talks about how complex ancestry actually is.
/10
Just by moving further back in time when doing the analysis, you can obtain completely different percentages. These studies focus on a very specific time.
Also, the dynamics of populations make it really difficult to reduce the origin of your genes to simple percentages.
/11
Also, the dynamics of populations make it really difficult to reduce the origin of your genes to simple percentages.
/11
This was also talked about by Prof. Dibble in one of his previous lectures. There is a lot of overlap and ambiguity in humans' genetic makeup that we can't define it with our modern understanding of race/ethnicity (Dibble).
/12
/12
Archaeogeneticist Eirini Skourtanioti's findings on her research study focusing on the ancient DNA remains from Anatolia and the Caucasus-a region with lots of ethnic complexity-supplements this idea, as she finds that there was a huge genetic homogeneity (Interview).
/13
/13
A study that we had read about in Renfrew and Bahn's book, talks about similar findings within the more general region of Europe (Bahn 475).
The combination of information from the podcast and our classes suggest that ancestry tests are not that meaningful after all.
/14
The combination of information from the podcast and our classes suggest that ancestry tests are not that meaningful after all.
/14
Also, all of these studies from class readings and lectures that I mentioned, in addition to the study explained by Zaidi, show how crucial biological-especially genetic- methods are for archeological studies.
/15
/15
Nasal aperture image: https://pocketdentistry.com/27-nose-nasal-cavity-and-paranasal-sinuses/
Nose map image: https://archandanth.com/episode-26-interview-with-arslan-zaidi/
Citation:
https://archandanth.com/episode-26-interview-with-arslan-zaidi/
Dibble, Flint.
Interview.
Bahn, Paul G, and Colin Renfrew. Archaeology: Theories, Methods and Practice.
/16
Nose map image: https://archandanth.com/episode-26-interview-with-arslan-zaidi/
Citation:
https://archandanth.com/episode-26-interview-with-arslan-zaidi/
Dibble, Flint.
Interview.
Bahn, Paul G, and Colin Renfrew. Archaeology: Theories, Methods and Practice.
/16
