What is one of the best or most worthwhile investments you have ever made — of money, time, or energy?

Amos and I shared the wonder of together owning a goose that could lay golden eggs – a joint mind that was better than our separate minds. … Some of the greatest joys of our collaboration-and probably much of its success – came from our ability to elaborate each other's nascent thoughts: if I expressed a half-formed idea, I knew that Amos would be there to understand it, probably more clearly than I did, and that if it had merit he would see it. Like most people, I am somewhat cautious about exposing tentative thoughts to others – I must first make sure that they are not idiotic. In the best years of the collaboration, this caution was completely absent.

Sherry offered me a list of research options: the one project that intrigued me the most consisted of finding out the environmental fate of certain very inert industrial chemicals – the chlorofluorocarbons (CFCs) – which had been accumulating in the atmosphere and which at that time were thought to have no significant effects on the environment. This project offered me the opportunity to learn a new field – atmospheric chemistry – about which I knew very little; trying to solve a challenging problem appeared to be an excellent way to plunge into a new research area.

Well, it is of course a step-by-step process that started back in the 80s. I was struggling to retrieve a little bit of DNA from things that were just a few … starting with just dried tissues that, you know, that were just a few months old, going back in time and struggling with the technological issues with that over a decade. And then it became possible to retrieve DNA from things like the mammoths or cave bears that lived at a similar time as the Neanderthals. And then I was very lucky to get a job in Germany, where of course Neanderthals is a big presence in our, in the imagination of people, so it was then very, an obvious next step, in a way, to try to do that.