Deep Ancestry - Spencer Wells

 Sub-title: Inside the Genographic Project - The Landmark DNA Quest to Decipher Our Distant Past

Over the summer, the Southern Arizona Genealogical Society had a book sale at their site in Green Valley.  A friend and I took a day trip to explore their offerings and came home with many future reads, this title being one of them.

 The National Genographic Project was a research project initiated in 2005 to document the paths of human migration over time, using YDNA and mitochondrial DNA.  The project gathered DNA samples from many indigenous people around the world as well as offering DNA tests for sale to partially fund its efforts; some of you may have participated in the project.  The project was closed in 2020 and test results are no longer available to testers. 

 The focus of the research was to expand the data used to conduct anthropological investigations of human migration.  In the book, Wells describes the migration path of homo sapiens out of Africa and across the globe.  I was fascinated with how the YDNA and mtDNA haplogroups evolved over tens of thousands of years.  This book expanded my knowledge of haplogroup studies.  The last chapters takes the reader through the evolution of both lineages and makes a good resource for understanding the sometimes confusing jumble of haplogroup names.  

Quotes:

"In August of 2002 I had recently finished a film and a book, The Journey of Man."

"Members of the Q [haplogroup] lineage share the genetic marker M242 with the people living in Siberia...When they arrived in North America, they were the first humans ever to inhabit this continent."

"This disconnect between the individual event and the sum of many events is a result of a statistical property known as the law of large numbers.  The error introduced by using a small number of events is known as sampling error.  What does all of this have to do with genetic lineages?  The likelihood of passing on one's genes varies from person to person, but if we have a large number of people, then it tends to even out in such a way that the variation distinguishing the population is transmitted to the next generation in the same proportions seen today.  The change in frequency from generation to generation due to sampling error is known as genetic drift."

"..we still know very little about the underlying genetic changes that determine human appearance.  As these genetic markers are discovered...we should be able to test the theory that humans diverged in their surface features due to sexual selection.  Exploring this idea is one of the goals of the Genographic Project."

"...results were finally confirmed in a study published in 2000 that narrowed the estimated date [of mitochondrial Eve] to around 170,000 years, mitochondrial Eve was African."

"In a paper published in 2000...it showed our common Y-chr ancestor lived only 60,000 years ago.  [Because of] variance in reproductive success, is higher for men than women, which means that women have more equal opportunities to have children...tends to reduce the effective population size of the Y chr.  Over time, this meant that Y lineages were more likely to be lost than mtDNA lineages.  The result is that the deeper Y lineages were lost over the past 170,000 years, and the only ones left date to around 60,000 years ago.

Published: 2006  Read: July 2021  Genre: Science