Once humans and machines merge—in 2045, according to Kurzweil—reproduction will no longer be a biological necessity. So why and how will we continue to have sex?

Ray Kurzweil: Sex, I think, is going to stick around. That was innovation that actually came along with death. Before sexual reproduction, these cells were immortal, because they never died, they would reproduce asexually. I think we'll keep the sex, and get rid of the death.

Sexuality has become a form of communication and it’s obviously a rich area of human activity and communication. We have already separated sexuality largely from its biological reproduction. We can have reproduction without sex; we can certainly have sex without reproduction. So we have already kind of isolated it as a communication medium and in that regard, it’s important. I think all these technologies enhance our ability to communicate. And sexuality has always been an important part of new media technologies. 

Virtual reality will be an opportunity to expand all kinds of human relationships, including physical, sensual, and sexual ones, which very soon are going to become full emersion, with 3D TV and things like Project Kinect from Microsoft, where the computer can pick up your movement. We’re going to be in the action. You’re not just going to be watching virtual reality, you know, here on a little screen, you’re going to be in it.

And there won’t be this cartoon-like thing we have now; it’ll be very realistic. We’ve had some technologies where you can change who you are, you can wear different fashion. But we’re going to have much more flexibility if you can really change your whole body. So it can be just a game or it can be an educational experience or it can be a different way to have relationships.