Matt Smith believes the purpose of life is to ''procreate''.

The former 'Crown' actor - who is in a relationship with actress Lily James - admitted his family and friends are vital to his existence and while he also likes to ''take risks'' and have fun, he thinks ultimately he was put on earth to have children.

Asked what he thinks is the purpose of life, he said: ''F**k knows! You're asking the wrong guy. But for me it's my family and friends, getting involved. Taking risks, not looking back. Laughing as much as you can. I don't know. Who knows?

''Every day unveils something different. But children and family are what I'd put at the top of that list.''

He also said: ''Essentially, the purpose of us all is to procreate.''

The 36-year-old actor worries about climate change but admitted he is aware he could ''do more'' and believes it will take having children of his own to spur him on to consider the issue more.

He told the Sunday Times Culture magazine: ''The idea that Greenland is melting freaks me out. Yet am I an active campaigner? Do I do enough? No...

''I'm not saying, 'It doesn't exist, guys.' But I could do more. I eat meat. Not loads, but I like a roast. And I drive a car. I don't not get on planes....

''Look, how is Greta getting back from America? [Boat?] So she'll sail back? Who has the time, and how much does it cost to charter a boat and sail it across the ocean? This is what I mean about bigger thinking, for all of us. We just need more ingenuity. But the plane thing is tough. I won't not fly, because I've got to get where I'm going.

''Basically, my climate-change anxiety is really random. I'll go, 'Oh man, polar bears. F***ing polar bears!' I'll wig out about them not having ice to get back on.

''I operate in my little sphere, but I don't think about it enough in a global sense. I don't have children yet, but having them would make me think about it a lot more.''