Wednesday, October 25, 2006

Extinctions update Book gives poor explanation for death of ‘mega-mammals’
So, who or what killed 35 genera of mammals, including mammoths, mastodons, giant beavers, horses, camels, saber-toothed cats and short-faced skunks?

Martin says archaeologists and paleontologists who think climate change might have caused the extinctions "are in deep denial." When you consider the evidence, however, it is Martin who seems in over his head.

He concedes there is little evidence that people killed any of these animals, except for 14 accepted mammoth and mastodon kill sites and one or two possible cases of horse and camel kills.

However, he doesn’t see this lack of evidence as a problem. In fact, Martin says the lack of kill sites supports the "overkill model." He says it all happened so fast that the event might have left few traces in the fossil record.

Lepper also queries: But what about the short-faced skunk?

Those are two of the big arguing points between the Grayson/Meltzer camp and the Martin camp. The former have argued that the Overkill theory has evolved so much to suit whatever evidence turns up that it is virtually unfalsifiable. The short-faced skunk has been dealt with by assuming that whatever other species went extinct were somehow ecologically related to the megafauna.

The absence-of-evidence one, well, I'm not too keen on that one. In a geological sense, mass extinctions are generally characterized by a lack of remains. But those are over much longer time frames much deeper in history. This seems to be the only case where we might infer resource abundance inversely. That is, at any other, say, Magdalenian site we would assume that more reindeer bones means more of them were being hunted relative to other critters. Why would Magdalenian hunters bring all their food back to the site, while Clovis hunters didn't? (Actually, the Overkill people have an explanation for that, too: Clovis didn't have the big central sites that other Paleolithic hunters did).

I suppose I'm being a bit snarky, but I really suspect that if a few dozen undoubted megafauna kill sites were found next week, Overkill would all of a sudden be perfectly happy with abundant remains. . . . .