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Notes from Planet Earth

What happened to the woolly mammoth?

Sixty years ago we were fond of remarking that humans seemed to spend an inexplicable amount of time talking about the weather considering the fact that no one could do anything about it. Ironically, we've now learned that humans, with potentially drastic consequences, have indeed been altering our climate, albeit unintentionally. This new knowledge has been so shocking and bewildering for some that they adamantly refuse to believe it.

Now it turns out that ours may not be the first human era to have had major effects upon our biosphere. As scientists have attempted to decipher why most of the large fauna (think mammoth, mastodon, ground sloth, and giant kangaroos, among others) that roamed the temperate climes of our planet up until about 13,000 years ago became extinct, they have offered three possible hypotheses: Might it have been a nuclear winter-like climate brought on by the collision of a comet or large meteorite with Earth? Or was it a prolonged period of massive volcanism that gave rise to a similar prolonged cold climate brought on by dense clouds and ash that killed the vegetation and led to the starvation of these megafauna? Finally, could humans, expanding their range over all the major continents as the glaciers of the last ice age receded, have hunted these creatures to extinction?

Surprisingly, the evidence unearthed to date gives no support for the first two hypotheses and quite definitely favors the third. Furthermore, the loss of these herds of large herbivorous mammals led to significant changes in the ecology of the lands affected. For example, because the formerly open and seldom burned savannas of North America were no longer heavily grazed, they were replaced by woodland comprised of spruce and broad-leaved trees and subject to more common wildfires.

It seems we humans, now constituting and utilizing a significant fraction of the available nutrients and minerals present on Earth, can have large impacts on our habitat. We survived the Stone Age, flourished during the Iron Age, muddled through the Middle Ages, and were awed by the Atomic Age. Is it time we gave rise to a Responsible Age?

Questions and suggestions from readers are welcomed and will be responded to in future editions of this column. Contact me at cwdingman@frontiernet.net.

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