The Late Pleistocene extinction event has been a topic of interest for a number of years with many ideas and as many proponents of these ideas. Not many notions ("hypotheses") of the event gain long term currency. Paul Martin, University of Arizona, was/is a leading proponent of the "Overkill" hypothesis. Martin proposed that the earliest human migrants (Paleoindians) arrived in the Americas, entering from the Bering Straits region, emergent with the great (100 meter) decrease in seal level, via an ice free corridor. They encountered an abundant and diverse fauna that, not having had interactions with humans, fell easy prey to these hunters, the Clovis people.A human overpopulation occurred and the hunters pressed fowarard in a wave, slaughtering all the megafauna in front of them, presumably until they reached Tierra del Fuego. Unfortunately this hypothesis can be criticized on many fronts. Firstly, it seems likely that different peoples entered the Americas at different times and possibly vis different routes. The recent conroversy of the Kennewick Man discovery illustrates this; Kennewick seems to hae not bee an "Indian" in an anthropologic sense. Secondly, not all the big animals died at the same time. Indeed, there are indications that mastodonts survived quite late in "refuge" areas, perhaps to 3,000 BCE. Similarly, shere is no coincidence of human involvement with all, or even most of the megafauna on a large scale. Then too, the major extinction event, mammoths, horses, slths, camels, lions, lep[oards, etc,etc, can be seen to generally coincide with the shift from a glacial climatic pattern to a modern climatic pattern---a very important coincidence. Not all the big animals went extinct and left "ecological gaps" because, all the modern forms replaced the ancient forms. The modern fauna (and flora) reflects the profound climate change from glacial and periglacial to modern climatic regions. A mammoth likely needed 400 pouns of forage/day and lots of mammoths and mastosdons roamed the modern Southwest. It would be difficult for these forms to live in the Southwest today (unless they robbed the farmers of the Rio Grande of their alfalfa and chile pepper crop).

I am struck by the recurrent theme in science for a grand explanation for events. This "infection" seems to have hit archaeologists and anthropologists just as it reached geologists and paleontologists. Neocatastrophism is thriving, yet in that proposed other world catastrophy, the extinction of the dinosaurs, the research of Gerta Keller, has raised major doubts about the hitherto simple impact scenario. The picture is much more complex and, to my mind, more interesting. The difference in the case of the Cretaceous extinction event, some 65 million years ago, is that there is substantive data to debate. Unfortunately, it does not appear to me that this is the case for the Pleistocene event.