There is no good scientific reason to bring back an extinct species. Why would one bring them back? To put them in a theme park?

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.

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.

Teeth actually turn out to be one of a couple of good sources of ancient DNA. The teeth, actually the enamel, is quite good at preserving the DNA, so it is a bit of time capsule so to speak.

Given enough time, polar bears might migrate off the Arctic ice, evolve darker coats, find a different diet, and thrive in a new, warmer climate. But if the ice on which they depend disappears in a few decades, they are likely to die.

We know humans have most flourished during times of what? Warming trends. So I think there's assumptions made that because the climate is warming, that that necessarily is a bad thing. Do we really know what the ideal surface temperature should be in the year 2100, in the year 2018?

Design our world so that we have positive social and environmental side effects.

Wealth and vegetation go together, and that exacerbates environmental injustice. The poor bear the burden of degraded environments.