Archaeologists and paleontologists examining the historical pathways of modern humans as they left Africa and colonize the remainder of the planet have discovered a disturbing combination of effects.
Mastodon Sculpture, Page Museum La Brea Tar Pits, California, photo by Rons Log
It seems that, wherever we went, severe impacts to both plant and animal life and climate change came with us. After humans colonized the Americas and Australia, those lands were irreversibly altered. Dozens of species of plants and animals died, and cooling and then warming of the local climate occurred at the same time. The problem is and likely will be for some time to come, that we don't know which came first. It is possible that climate change in the form of glaciation and deglaciation drove migrating peoples from one continent to another. It is possible that humans over-predated the new species they found, because those species were on able to save themselves from the new predator. It is also possible that the death of massive number of animals drove climate change by upsetting the existing balance of plants and animals in the region.
So we don't really know who's at fault: it is perhaps most likely that the three elements of massive movements of human population, climate instability, and massive extinction of the genera of species of animals fed into each other, eventually creating the current balance of life and climate on our planet.
Comments
I always enjoy reading your e-newsletters, but I do wish you would proofread them or have somebody do so before publishing them. There are quite a few errors/typos in the current newsletter, which is not that uncommon an occurrence. Sorry to point this out, but …
oh, I’m so sorry, Stan! my only excuse is not a good one – I broke my arm couple of weeks ago and I’m struggling with time and proofreading the voice-recognition software. I promised to be more careful in the future. Thanks for your comment!
Kris
sounds like stan is a natural volunteer!
re: the megafaunal pleistocene extinction…let’s not totally disregard the cosmic impactor theory…
Kris: The claim that hunters, gatherers may have tipped the balance and caused climate change by killing megafauna and plants is stretching it-dont’ you think? What is the evidence for this? Sincerely, Doug Marsh
I have to admit, the data from Australia seems a bit light. Basically, the scholars could find no environmental reason for the die off of animals, and so they argue it must’ve been Hunter gatherers who are responsible. Like you, I have my doubts, but I of course am not a researcher. You might want to read that article by Rule and colleagues cited on the megafaunal extinctions page.
http://archaeology.about.com/od/mterms/g/megaextinct.htm
A very large mammoth, giant sloth or other such animal would make a lot of meals for early humans. Once a hunting method, such as using fire to drive a herd of animals over a cliff was developed, the rewards for the effort would be enormous. And most large animals have long life/breading cycles. So it would me harder for them to recover from over hunting than smaller animals.