Recognising if not the sanctity of the human embryo, then at least some form of moral status, the Lancet in 2001 declared that "...creating embryos with no purpose other than to use them as a source of stem cells is ethically unacceptable."

But the scientific excitement and alleged medical potential of embryonic stem cells (arguably amplified by the politics of abortion, which also implicitly devalues the human embryo), resulted in the widespread abandonment of such principles, with a huge expansion of human embryo research, new and ever more liberating legislation in the UK, including last year's law allowing the cloning of human-animal hybrids, and outcry in the US at the "Bush ban" on federal funding for many forms of embryonic stem cell research.

The paradox is that while 2009 might have seen new UK legislation combining with a new US president to open the floodgates for human embryo research, the likelihood is that such research may instead slow to a trickle.

While still carrying the therapeutic hazards of embryonic stem cells, including tumour formation, iPSCs offer a far easier and cheaper methodology than either cloning human embryos or obtaining stem cells from more traditionally produced embryos (i.e. on a Petri dish in an IVF clinic). So even those still convinced that embryonic stem cells, rather than adult ones, hold the key to the future, are more likely to pursue their aims with human iPSCs, not embryo-derived cells. Equally importantly, adult stem cell advances, often dramatic, now appear almost weekly - from tracheal transplants to the generation of a prostate from a single adult stem cell. These cells are safe, relatively accessible and avoid immune rejection (being derived from the patient himself, not other individuals). Adult stem cells also start with a medical and biological advantage: tissue repair is their evolved purpose. Repairing diseased adult tissue is hardly the evolutionary function of the embryonic stem cell.