What's so great about being human, anyway? The transhumanist movement -- epitomized by organizations like Humanity+ and blogs like Accelerating Future -- advocate the pursuit of technologies to fundamentally change the human condition, tinkering with our brain, bodies and genomes to make ourselves smarter, stronger, happier, and longer-lived.

But many people worry that tampering with human nature could have dire consequences for individuals and society alike. In Our Posthuman Future, political theorist Francis Fukuyama sums up the position of the bioconservatives when he warns that new technologies may "in some way cause us to lose our humanity -- that is, some essential quality that has always underpinned our sense of who we are and where we are going," he writes. In this episode of Rationally Speaking, Massimo and Julia ask, first, are the goals of transhumanism realistic, and second, are they desirable?