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The “placental explosions”

Spinger et al. doi: 10.1073/pnas.0334222100 By this time I’m sure you’ve encountered articles about the reconstructed last common ancestor of all placental mammals. Greg Mayer at Why Evolution is True has an excellent review of the implications, along with a link to a moderately skeptical piece by Anne Yoder in Science. Yoder’s piece is titled Fossils vs. Clocks, while the original paper is The Placental Mammal Ancestor and Read more...

Posted
February 10th, 2013

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The geography of genes tells us only so much about history

L. L. Cavalli-Sforza’s The History and Geography of Human Genes is a book I reference a great deal. Cavalli-Sforza is the godfather of the field of historical population genetics, the phylogeography of humankind. Though his work was on classical autosomal markers, the huge literature which drew inferences from Y chromosomal and mtDNA variation followed in the wake of the The History and Geography of Human Genes. Spencer Wells, the direct Read more...

Posted
August 25th, 2011

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How did modern humans settle the world?

In lieu of lots of text, above is a stylized representation of the routes which Neo-Africans took ~50 thousand years ago from their point of departure to parts unknown. The two colors represent two models. The red lines show two major streams issuing out of Africa, a northern route which pushed into the heart of Central Asia, and a southern oceanic one, which pushed all the way into Australia. The second differs, with eastern and western branch Read more...

Posted
July 10th, 2011

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“What if you’re wrong” – haplogroup J

Back when this sort of thing was cutting edge mtDNA haplogroup J was a pretty big deal. This was the haplogroup often associated with the demic diffusion of Middle Eastern farmers into Europe. This was the “Jasmine” clade in Seven Daughters of Eve. A new paper in PLoS ONE makes an audacious claim: that J is not a lineage which underwent recent demographic expansion, but rather one which has been subject to a specific set of evolution Read more...

Posted
June 29th, 2011

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You are a mutant!

The Pith: You are expected to have 30 new mutations which differentiate you from your parents. But, there is wiggle room around this number, and you may have more or less. This number may vary across siblings, and explain differences across siblings. Additionally, previously used estimates of mutation rates which may have been too high by a factor of 2. This may push the “last common ancestor” of many human and human-related lineage Read more...

Posted
June 13th, 2011

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Man at Bab el-Mandeb

In light of my last post I had to take note when Dienekes today pointed to this new paper in the American Journal of Physical Anthropology, Population history of the Red Sea—genetic exchanges between the Arabian Peninsula and East Africa signaled in the mitochondrial DNA HV1 haplogroup. The authors looked at the relationship of mitochondrial genomes, with a particular emphasis upon Yemen and the Horn of Africa. This sort of genetic data is Read more...

Posted
June 10th, 2011

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Adam was African, but perhaps barely

The figure to the left comes from a short paper in The American Journal of Human Genetics, A Revised Root for the Human Y Chromosomal Phylogenetic Tree: The Origin of Patrilineal Diversity in Africa. The paper is interesting because of two factors: 1) they sequenced more of the Y chromosome 2) their African data set of individuals was very large, in excess of 2,000. The weird thing about the results is that it upends one of the truisms in human Read more...

Posted
May 21st, 2011

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One root for rice

The Pith: There was one rice domestication event somewhere in central China about 10,000 years ago. Probably! Going by the numbers rice is the real staff of life. Rice is the staple for ~50% of humans alive today. So the science of rice is of major pragmatic importance of all humans (even if a major disease which impacts rice doesn’t result in mass starvation, it will probably generate a price spike for all other staples due to Asian dema Read more...

Posted
May 4th, 2011

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The continuing tangling of the human tree

Last summer I made a thoughtless and silly error in relation to a model of human population history when asked by a reader the question: “which population is most distantly related to Africans?” I contended that all non-African populations are equally distant. This is obviously wrong on the face of it if you look at any genetic distance measures. West Eurasians, even those without recent Sub-Saharan African admixture (e.g., North Eu Read more...

Posted
April 28th, 2011

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Visualization genetic distances, part n

Zack Ajmal has been taking his Reference 3 data set for a stroll over at the Harappa Ancestry Project. Or, more accurately, he’s been driving his computer to crunch up ADMIXTURE results ascending up a later of K’s. Because it is the Harappa Ancestry Project Zack’s populations are overloaded a touch on South Asians. He managed to get a hold of the data set from Reconstructing Indian History. If you will recall this paper showed Read more...

Posted
April 22nd, 2011

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