It's cold out there
I couldn't help noticing the last sentence of "World's climate map gets an update" (SN: 3/24/07, p. 190): "One of the system's 30 possible climate subtypes—a temperate climate with a cold, dry summer—wasn't found anywhere on Earth." The comment reveals that the writer has never read Mark Twain's comment that the coldest winter he ever spent was a summer in San Francisco.
Regarding "Mysterious Migrations" (SN: 3/24/07, p. 186), has anyone ever considered the possibility that interbreeding between Neandertals and humans would have produced sterile individuals? They would have had the traits of both parents, but with no further reproduction, Neandertal DNA wouldn't be found in humans today.
Researchers who argue for human-Neandertal hybrids say that fossil evidence argues against sterile, dead-end individuals.—B. Bower
A likely contributing cause of Neandertal's rapid demise in Europe would be the introduction of lethal diseases into their small, previously isolated populations.
The article mentioned a "third idea" of multiregional evolution. Didn't Carleton Coon propose something similar last century and come to grief because of it? Might be worth a mention.
J. B. Post
Carleton Coon was controversial for his theory that there are distinctive human racial groups, some of which are more evolved than others. Multiregionalists reject the existence of racial groups.—B. Bower