Transcript:

What is Life?This week, we'll explore one of the questions that we humans have carried for a long time. I'm Jim Metzner and this is the Pulse of the Planet.Zimmer: People have been asking "what is life?" for centuries, since the scientific revolution when they started to think about living things in terms of matter and forces and chemistry. They just started wondering, what is it that ties all these things that we consider alive together? In other words, what is life?Science writer Carl Zimmer is the author of the book "Life's Edge."Zimmer: It's kind of hard to imagine a more important question in life than "what is life?". This thing that defines our existence. Each of us are alive and our life is incredibly important to us and we share this planet with trillions of things that we consider alive. So what do we mean? What are we talking about? It's not just a profoundly important question to think about ourselves and life on earth, but what about life in the universe? Is the universe home to life elsewhere? If we're going to answer that question, we have to first figure out what we mean by this word "life".I think I've always puzzled over life and what it is. When I ask biologists "what's your definition of life?", a lot of them don't have a really good answer either. Or if they do, it's a different answer from the next biologist I talk to. That fascinates me, that even for biologists, it's so difficult to tie together all these things that they study into something that we call life.Our thanks to Carl Zimmer. We'll delve a little deeper into the frontiers of life in future programs. Check out our website pulseplanet.com for some exciting news. I'm Jim Metzner and this is the Pulse of the Planet.