Richard Dawkins wonders: We've mapped the entire human genome; we've mapped the entire chimpanzee genome.  We know they are 98% identical (sorry, evolution opponents).  It shouldn't be hard, therefore, to literally create some sort of interspecies.  Another "missing link".  Lucy the Second, not from the archeological ground, but from the laboratory.

It would, he speculates, change the nature of the discussion on abortion.  Pro-lifers insist that a single human cell — the zygote (which preceeds the embryo) – is sacred because it is human.  Therefore, in their view, destroying it is destroying a human which is "murder". 

But what if the zygote is 50% human, 50% chimp?  What about 70/30?  95/5?  99.999/0.001?

It is a thought experiment (although it could be done in reality) which really forces the issue of "what is human".