Every outbreak across the globe today stems from a descendant of the medieval plague.

You can go into caves, and they can maintain constant conditions of temperature and humidity over long periods of time, even though the outside temperature may be way above what it is inside the cave.

When I was a young boy, I used to gaze through the microscope of my father at the insects in amber that he kept in the house. And they were remarkably well preserved, morphologically just phenomenal.

It turns out that there are swaths of habitat in the north of Siberia and Yukon that actually could house a mammoth. Remember, this was a highly plastic animal that lived over tremendous climate variation.

I'm not sure the Russians would be happy that their iconic wooly mammoth has North American origins.

If we brought the mammoth back to Siberia, maybe that would be good for the ecosystems that are changing because of climate change.