Thought-provoking analysis of where we are currently with genetic engineering and where we could conceivably be in the near-term future. Disregards flora almost completely and focuses on fauna, specifically mammals. Cogent explanations of stem cells, and a lovely, lovely passage about ensoulment that I feel compelled to quote at length because there's nothing I like more than scientists talking about souls:"Then there is the question of the soul. It could be argued that while the fertilized egg has no brain, it nevertheless has a soul, and is therefore a person. But this proposition also raises some problems. When the zygote's single cell divides to make two cells, we know that each of these is capable of making a person. And indeed this is true through the eight-cell stage, through the accidental splitting of a single early embryo into two or more parts, which then each proceed to make a complete individual- identical twins, triplets, and so on. If the early human embryo has one soul, and then the embryo splits, do the twins, triplets, and such only receive a piece of the soul? Do they share a soul? Or do new souls enter at this later stage to fill the gap, the shortage of souls? And conversely, what happens when two early embryos fuse together to form one chimera? Do people that are chimeras have multiple souls? Or does one soul now leave, because of a soul excess?"This is but a snippet of an extended analysis of when humans become 'human', how inconsistent the populace's feelings about stem cells really are (okay for IVF, for instance...) and how a little logic really lights up a dark place.Written in fairly nonscientific language, and to my eye very balanced. Recommended.