With enough money and international coordination, we can push incoming asteroids out of Earth's path. We might even be able to bring back extinct animals in the lab. The problem really isn't scientific - it's cultural. We aren't yet able to coordinate ourselves as a global civilization to do something simple like bring food to a famine-stricken region. We can actually use current satellite technologies to predict where famine will strike next, but we can't get food there - usually for political reasons.

So science alone cannot solve this problem [mass extinction of humans]. It's something that we can only tackle by bringing science together with culture, economics, and even politics.

I think small animals can escape from many kinds of natural disaster more easily. There are just more places for them to hide, and more ways for them to find safe habitats. So this means that rats are set up to rule the Earth, but most of us already knew that. Now you know why.

A lot of environmental and biological science depends on technology to progress. Partly I'm talking about massive server farms that help people crunch genetic data - or atmospheric data. But I also mean the scientific collaborations that the Internet makes possible, where scientists in India and Africa can work with people in Europe and the Americas to come up with solutions to what are, after all, global problems.

I think it's the process of demystification, and realizing that we are not talking about some supernatural nightmare - we're talking about a natural process that the planet has gone through before, and which animals have survived before.

There are definitely recurring themes in humanity's relationship with our environment. The biggest is probably adaptation, because humans are incredibly good at adapting to new environments in relatively short periods of time. The ancestors of Homo sapiens started leaving Africa over one million years ago, moving from warm, tropical climates into the freezing wilderness of Europe and the desert ecosystems of the Middle East.

Even though I now know that it's likely the Earth will suffer through mega-volcanoes or meteor strikes that could take out millions or billions of people, I feel less anxious about it because I actually understand what the threats are. There's nothing like researching something exhaustively to make it less terrifying.