Human activity, either directly (e.g. the Dodo) or indirectly (e.g. the Amazon rainforests).
How is the destruction of the Amazon rainforests any less a result of human activity than the extinction of the dodo? Both are due to humanity's ceaseless drive for resources, no matter if those resources are tasty easy-to-kill birds, or lumber, or the farmland to raise other types of tasty easy-to-kill birds.
Disaster Area, here we come!
We can rebuild him; we have the technology. But I don't want to spend a lot of money... [/familyguy]