This Week in Human Evolution

Carl Zimmer in his blog, The Loom:

I wanted to write up a quick post to draw your attention to three very interesting pieces of human evolution in the news.

1. Modern evolution. A new paper presents the results of a systematic scan for human genes that have experienced natural selection in the past few thousand years. An impressive 700 regions turned up. The fact that humans have been evolving during recorded history is not new. The ability to digest lactose in milk as an adult, resistance to malaria, and other traits have long been recognized as having experienced strong natural selection after the dawn of agriculture. But this new study certainly sets the standard for all future work in this area, because it is so thorough. (Gene Expression takes you through the steps. The original paper is here.) The next logical step would be to add new populations to the database. The new study compares only three populations–Yorubans from Nigeria, Chinese and Japanese, and people of European descent in Utah. I wonder how different the evolutionary pressures are in other groups. Inuits get no benefit from malaria resistance, for example. Lactase digestion turns up in people descended from cattle herders. Are there adaptations for eating rice, cassava, or blubber?

More here.  And this also by Zimmer in The Loom:

This image came out a couple months ago in Nature, but I just came across it today. I quite like the way it sums up the history of life–something that’s maddening hard to do, since the time scales are so vast. It shows how life’s diversity has been accumulating for billions of years. This chart shows the timing of the earliest paeolontological evidence for different kinds of life, ranging from fossils to chemical markers. A few definitions may help. Phototrophic bacteria can harness sunlight to grow. Cyanobacteria are also known as blue-green algae (aka pond scum). Eukaryotes are species such as amoebae, plants, fungi, and animals. Algal kindoms include red algae and green algae (closely related to land plants). Some of these bars may need to be pushed back in time when earlier evidence is discovered. Some studies on DNA suggests that a number of such “ghost lineages” remain to be discovered.