Madam, - Vincent Twomey (November 20th) is surely correct to say that current scientific knowledge underwrites the equal biological status of all human pre-implantation embryos irrespective of their origin or location. The full potential of such embryos, whether produced in the laboratory or through natural conception, is identical: given the opportunity, both groups will, with varying degrees of success, continue to develop in the womb.
However, Dr Twomey should take care, when invoking scientific arguments to support his case, to familiarise himself with the full spectrum of current scientific thought on human evolution. He may find that his "pro-life" stance and the science of human evolution make for uncomfortable bedfellows.
All life on the planet, from unicellular organisms to ourselves, is part of a gigantic evolutionary continuum. Our species evolved by multiple minuscule increments from an ape-like ancestor which we share with the chimpanzee. It is solely because intermediate ancestral forms connecting us to the apes are extinct that we perceive ourselves to be fundamentally separate or superior.
It is not possible to defend scientifically a special status for the human individual, whether embryo or adult, without extending the same courtesy to our close relative, the chimpanzee and, by extension, to all life on the planet.
Notwithstanding these arguments, hunger being the mother of pragmatism, we allow ourselves the luxury of eating many of our sentient relatives in the animal kingdom.
There is no scientific argument that justifies special status for human embryos over embryos of other species such as the chimpanzee. Since any such distinction must be arbitrary, we are free to adopt a pragmatic and, hopefully, humanitarian approach to these questions. In my opinion, the 2005 report of the Commission on Assisted Human Reproduction adopted a reasonable stance in allowing for the possibility of important medical advances through research on non-sentient human pre-implantation embryos. Conversely, those who adopt a "pro-life" stance on this issue would do well to found their arguments solely on moral, ethical or religious grounds as they will obtain little comfort from an informed scientific understanding of humankind's place in nature. - Yours, etc,
TOM MOORE,
Developmental Genetics
Laboratory,
Department of Biochemistry,
University College Cork.