Believing that "Clovis" was the first human population in the New World 13,000 years ago and was responsible for megafauna extinction is a nice bedtime story. "Clovis" was a very specialized adaptation by already existing populations to exploit dying mammoths. The climate was changing and megafauna couldn't adapt, but people could, and for a very brief time used beautiful--and rare--"Clovis" spear points to exploit weakened mammoth populations.

By the way, not all New World megafauna became extinct: the American Bison still exists, and it wasn't Native Americans who brought it to the brink to extinction.

Steven Gibson quote above: 'Climate change at the end of the last ice age undoubtedly had an effect as well -- perhaps a dominant one.'

Although I agreed with almost all of Mr. Gibson's comments above, I excerpted a quote of his relating to climate change being a culprit in the mass extinctions of the American megafauna which began approx 50,000 years ago.

Mr. Gibson may not realize that the 'last ice age' is merely the last one we've had since humans began the Neolithic era. There have been many ice ages during the past 2.5 million years & climatologists forcast that we'll have another one (or would have had, prior to Global Warming) in another 20,000 or so years. During each of those past ice ages (except the last one) the American megafauna managed to weather the climatic changes. What, one might say, would be the difference between this last Ice Age & the 10 or so that preceded it?

Cynics, such as myself, would say that the diference was the new species of predator that entered the American continents through the land bridge temporarily connecting Asia with North America. I'm sure we all know who I mean. Many laypeople have the idea of the paleolithic hunter as a caveman version of Grizzly Adams, relentlessly tracking his quarry & attacking in small groups with some form of javalin or spear.

IMO, this is a falacious archtype that causes people to wonder 'how could these small bands of wandering nomads have killed all those Mammoths, Mastadons, Ground Sloths, Giant Bisons, Giant Cammels, Glyptodonts, Smilodons, American Lions, Dire Wolves, Homotheriums and Short Faced Bears?'. The answer is that these first hunters did not hunt in the way that many people assume they did.

These people were killing for sustenence in a very hostile environment & could afford no sporting nature or desire to give the quarry a fair fight. IMO, they hunted in large part by stampeding the animals over cliffs & when possible setting fires to kill prey. This way of hunting is unfortunately very wasteful of the prey & since the American megafauna, by virtue of being near the top of the food chain, was not very plentiful to begin with, such hunting tactics had an affect on those prey species all out of proportion to the numbers of those doing the hunting. Another contributing factor was that unlike other prey species who almost always attack the old, weak, & sick of a species, early American hunters would take the largest & fittest as well when they employed the tactics I outlined above.

Bottom line, I believe the American megafauna's disappearance is totally due to predation by man & that the time when you see the megafauna beginning their decline (approx 50,000 years ago) is when Homo Sapiens Sapiens hit the scene.

My father was fond of pointing out that at the rate they're silting up. all our reservoirs will be lovely wetlands in only a few centuries. Imagine Lake Powell, Lake Mead, the huge pools on the upper Missouri as vast seas of reeds, cat-tails, and willows, of poky little streams and backwaters like the the San Joaquin / Sacramento "delta" below Sacramento. Billions of waterfowl, beaver, mink, otter, cranes.

Lakes are geologically evanescent; they are followed by marshes that are even more evanescent.

For the long view, you might like to read George R. Stewart's _Earth_Abides_. I'm personally fond of Paul Errington's _Of_Men_And_Marshes_, with the beautiful pen-and-ink drawings by Hochbaum.

Estimated world Population in 1500:

low: 425,000,000

high: 540,000,000

http://www.census.gov/ipc/www/worldhis.html

"From a supply standpoint, 20 percent of the people in the world lack access to potable water. There has been a threefold increase in the global population in last 100 years and a sevenfold increase in water consumption." - Ira Ehrenpreis

Whatever the practices of the indigenous peoples of the Amazon Basin the populations were relatively small probably fairly stable over time and the technology fairly primitive.

It's what happens when these practices are carried forward with unsustainable and explosive population growth and vastly expanded technology. You have only to look at Malaysia where traditional slash and burn practices have truly run amok, causing deforestation over vast tracts and producing smoke and ash degradation to the air quality of the whole region. Deforestation is approaching 85%.

- Dec. 2006 estimate 26,920,000

- 2000 census 23,953,136

- 1971 estimate 10,423,000

Oh and I got a good laugh at this:

By THE ASSOCIATED PRESS

Published: March 2, 2007

China’s population grew by almost seven million people last year, to 1,314,480,000, the National Bureau of Statistics said in a report.

In a pig's eye. 70M maybe.

That's some science that can predict what would have happened to the American ecology if the Europeans hadn't arrived!

There is evidence that indigenous people did consciously work within the given constraints of their particular ecologies. The Mohawks moved their settlements every 20 years as they became depleted and cycled back when the area had regenerated. The fact that their constraints were much different than modern ones, doesn't mean they weren't managing them.

Native people have amazing powers of observation. With no grocery store down the block they have to.

We should be careful about drawing unsupported inferences - EcoRomantic or otherwise.

M

yeah,they were cutting trees, , but they didn't have bulldozers for god's sake, and it was their land , not ours.they weren't cutting them down out of greed for riches.

the indigenous populations of Central America were every bit as lethal to the rain forest as modern humans are, albeit perhaps on a somewhat smaller scale.

Either the indigenous Indians of Central America were every bit as lethal to the rain forest as we are, or they weren't. If their slash-and-burn activities were taking place on a smaller scale, then they weren't "every bit as lethal" to the rain forest as we are.

Mr. Leonard's article blithely ignores the fact that the indigenous Central Americans of whom he writes did not have bulldozers and chainsaws. They weren't clearing an acre a minute. Even if they "significantly modified" the existing rain forest, they did it over a much, much longer period of time than modern people have had available to them.

All this means is that there's no way that the indigenous destruction of rain forest is anywhere close to the same scale as ours; therefore they are not "every bit as lethal."