I'm not going to let you get away with playing the "skin" card. You don't have personal knowledge of the actions of Native Americans across a span of tens of thousands of years.

Speaking of bones, what the record--fossil and archeological--shows repeatedly, in Australia and many isolated Pacific Islands as well as North and South America and southern parts of Africa, is that like clockwork, immediately upon the arrival of humans in a land that hadn't known humans before, there were mass extinctions. 40,000 years ago people made it to Australia, and a rich fauna of large marsupial analogs to bison and rabbits and wolves and chickens--food animals--disappears from the fossil record. Indeed, the last traces of those species is bones in the campfire pits of hunter-gatherers and in their middens.

When humans arrived in the Americas, archeological records show that it took them only about a thousand years to travel as far south as Tierra del Fuego. That's actually only a few miles per year on average and not remarkable. It merely demonstrates a population exploding in a virgin land, whose voracious appetite could be sated by vast quantities of food. Mammoths went extinct, bison survived in isolated pockets (I think what we saw in the 19th century represented a population resurgence, not evidence of the true status quo as it had been for thousands of years), and many smaller species went extinct.

It's been observed that if those extinctions were all coincidental, why were species used as food by humans selected preferentially to die out? Why were humans not only unaffected by a hypothetical ecological catastrophe but indeed thrived? How counterintuitive is that?

Understand that I'm not assigning blame. "Overnight" in geological terms is still much longer than the span of an individual human lifetime, and on our scale the extinctions were gradual and largely imperceptible. As long as people could compensate for a local extinction by moving to virgin territory, there was no problem to perceive; and by the time the phenomenon could be perceived, there was nobody alive to remember how it used to be. The phenomenon of species extinction, until recently, has been below the human radar. No sense berating our ancestors for not knowing what we know now. That's why I was careful to say that "With 20/20 hindsight we know it was ultimately foolish for the Native Americans to drive herds of buffalo off cliffs and into extinction..."--"hindsight" and "ultimately" are the two key terms.

Human expansion has always been accompanied by extinction, sometimes including subsets of humanity. Nobody's ancestral hands are clean. Finger-pointing's a waste of time, let's be concerned about dealing with the obligation laid upon us now by the curse of knowledge.