Cultural differences of "invasiveness."

Homo sapiens is the most invasive species that this planet has known, though I wonder if it's an inherent quality of our species. Take, for example, the history of human occupation in North America. Some 25,000 years ago humans crossed the Bering Strait (at that time a land bridge) into North America. These early peoples might be considered non-native, but the migration was natural (in the sense that technology didn't play a direct role). Whether or not early humans caused the extinction of the native megafauna ~10,000 years ago is still up for debate, but hunting pressure likely did play a role, if not the defining role. During this time the people of North America were certainly exhibiting the hallmark traits of an invasive species (non-native, rapid spreading, and causing major changes to the ecosystem which resulted in the decline and/or extinction of native species). For the 15,000 years prior to that, however, "invasiveness" is more difficult to discern. Moreover, between the great extinction event and the later centuries of this past millenium, most human cultures had become fairly well naturalized.

This isn't to say that Native Americans had no impact on the native ecosystems, because they did. Areas were burned to promote the growth of grasses (for pasture) and berry crops. Humans acted as a top predator, though it's significant that they didn't extirpate the other top predators (namely the wolf, which acts as a keystone species in at least portions of its range). Pre-Columbian cultures in general had an understanding of the continent's ecology, and the role of humans as part of that system. In other words, they lived sustainably and the native species were largely doing well.

Then comes Western civilization. Even before Westerners gained a significant foothold in North America, the areas that they did colonize they modeled after settlements in Europe. Still, not a huge ecological impact but the Industrial Revolution would change that. The idea that nature needed to be conquered and that resources existed to be gobbled up is a Western notion, and we wasted little time in changing the face of this continent. The Native Americans existed for thousands of years with the giant bison herds, relying on them for sustenance and culling herds much like any other large predator. In a remarkably short time frame after the expansion westward started, the herds were almost completely decimated. Even the megafauna during the extinction event 10,000 years ago took several thousand years to progress from initial decline to full extinction. If it weren't for a small refuge population in the (at the time only semi-protected) newly established Yellowstone National Park, the bison would have gone from flourishing to extinct in about a century. Indeed, this did happen with the Passenger Pigeon, flocks of which used to darken the skies and take hours to pass overhead because of the immensity of the group. The native cultures didn't make a dent in those populations, but Westerners managed to decimate them in short order.

Humans may be the most invasive species this planet has ever seen, but not all cultures participate equally. Western culture may be the biggest offender (in any case, we're the biggest offenders that I can think of), especially since we've displaced so many native cultures that actually lived sustainably, with respect for ecological processes and culturally mediated empathy for other species. The question now becomes, can a major cultural shift away from certain Western ideals and assumptions decrease the invasiveness of our species? Or have the cultural choices made generations ago, which led to our bloated population, already cemented the invasive qualities into us forever (barring global catastrophe)? I see a voluntary reduction in fecundity, a completely counterintuitive conception for any organism, as the best solution to overpopulation. But then here I've gone and strayed from the main point about culture and invasiveness. I think I'll just cut myself off at this point.

References:

Wikipedia (this is just a blog, I can cite wikipedia if I want!)

Yong, E. 2009. Tiny Fungi Replay the Fall of the Giant Beasts. ScienceBlogs.

Ripple, W.J. and Larsen, E.J. 2000. Historic Aspen recruitment, elk, and wolves in northern Yellowstone National Park, USA. Biological Conservation: 95, 361-370.

Burns, K. 2009. The National Parks: America's Best Idea. PBS.