Compiling a Worldwide Genetic Atlas

Just amazing: tracing the genetic legacy of Alexander the Great in Central Asia, among many, many others:

Dr. Myers and his colleagues have detected European ancestry that entered the Tu people of central China between the 11th and 14th centuries; this, they surmise, could be from traders traveling the Silk Road. They find among Northern Italians an insertion of Middle Eastern DNA that occurred between 776 B.C. and A.D. 550, and may represent the Etruscans, a mysterious people said by the ancient Greek historian Herodotus to have emigrated from Lydia in Turkey.

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Die, Silly Journalistic Convention, Die!

My feelings about Richard Dawkins are conflicted at best — he’s brilliant and The Blind Watchmaker is a fantastic book but he seems to have become kind of an asshole sometime in the last ten or twenty years. However, this article (“Die, Selfish Gene, Die!”) is just silly. Dobbs huffs and puffs trying to force a supposedly counter-intuitive spin onto what is, from my reading, a well-established and not terribly controversial idea: that phenotype depends in large part on the specifics of gene expression rather than simple genetic makeup. And he takes forevvvvvvver to do it, picking a senseless fight with Dawkins in the process in order to create the sort of “contrary to perceived wisdom” narrative that magazine journalists love nowadays.

Ian Tattersall, meanwhile, briskly explains the phenomenon in a page or two of his excellent book Masters of the Planet: The Search for Our Human Origins:

ian-tattersall-photo_profile_fullIt has long been known that most protein-coding genes act to determine more than one physical characteristic, and that most physical features are determined by several genes. But it was widely assumed that there must have been a general relationship between the number of genes and the complexity of the organism, and the recent discovery that humans, with their billions of cells, have only around 23,000 protein-coding genes — about the same number as a tiny nematode worm with only 1,000 cells — came as quite a shock. What’s more, the protein-coding genes turned out to make up only about two percent of the whole genome, as the totality of the DNA in our cells is called. How could so few genes govern the development of an organism as intricate and complicated as a human being? And what was the rest of the “junk” DNA doing?

The answers to the two questions are closely related. Some ingenious recent investigations have shown both that the effects of a coding gene depend largely on when and how long it is active in development, and that part of the “junk” DNA is significantly involved in switching protein-coding genes on and off during that process. It also turns out that a coding gene’s effects depend on how active it is during the time it’s enabled by those “switch” genes, and that yet other stretches of “regulatory” DNA govern the vigor with which the coding genes are expressed in the development of the tissues. What is more, differences in the expression of the same basic gene may have huge consequences for the phenotype (the observed features of the individual).

Seems pretty straightforward. But hey, take that, Dawkins!

Tattersall’s book is excellent, incidentally–it’s a solid summary of the current state of paleoanthropology, and it’s mercifully free of the weird throat-clearing tics so common in popular science writing nowadays (I’m looking at you, Connectome). Plus it has the greatest “oh you caught me in the middle of my work” author photo ever — see above, Tattersall barely stops writing in order to throw a sullen glance the photographer’s way.