A
Abbadon
Guest
A crucial part of vitalist objections to hESC (Human Embryonic Stem Cell Research) is that embryos are human individuals and it is therefore unethical to destroy them. However, the criteria by which human individuals are identified as a individuals are no absolute. The transition between the haploid and diploid stages of human development is sometimes considered to be the defining moment of a new human individual, even though fertilization is a complex process. [1] The Catholic Church’s Concregation for the Doctrine of the Faith has declaed that when ‘the ovum is fertilized, a life is begun… the life of a new human being’
[2] This is problematic for three reasons: monozygotic or identical twins, chimerism and parthenogenesis. It is commonly known that identical twins have identical genes, which can be traced back to a single fertilization. If fertilization were used as the absolute and definitive beginning of the human individual it would leave room for only one person to be produced per fertilized egg. It is therefore unrealistic to use fertilization events to distinguish between human individuals.
Without looking to much into identical twins and chimerism I would like readers of the post to consider parthenogenesis and the moral and definitive issues which it presents.
Fertilisation events are also unnecessary for initiating development. Parthenogeneisis occurs when offspring are produced without the need for fertilisation. It has been observed in many species, including the Komodo dragon [3], and human eggs may be activated so that they develop parthenogenetically [4]. A collaborative effort between scientists from RUssia and the USA even managed to derive hESC lines from parthenogenetically activated eggs [5]. Although human embryos produced through parthenogeneisis have not yet survived to maturity, this development allows many objections to hESC research to be avoided, as fertilization is not involved
In principle, it ought to be possible for parthenogenetically-derived embryo to survive to maturity even though actually doing so would raise its own set of ethical concerns. However, the assumptions essential for vitalist objections to hESC research would require the adult human parthenote to not be considered an individual.
Just as an ant produced by parthenogenesis is an ant and a distinct member of the colony, the hypothetical human parthenote would also be a distinct human individual. The use of fertilization events as the absolute signifier of the beginning of human life would deny that the parthenote was an individual, which is false in the same self-evident fashion as the idea that identical twins are one individual.
This suggests that it is not appropriate to use fertilisation as a signifier for the beginning of a distinct human life and superior criteria should be developed.
Bioethical debates surrounding hESC research-should take into account that life is an ambiguous category and that suitable criteria for defining human individuality are not clear and simple. The approach of often religiously motivated vitalists fails to consider that science is unable to define human life with the precision required for thier arguments to work. As Nature editorial on the topic of synthetic biology remarks, “The formation of a new being is gradual, contingent and precarious…” While there should always be room for society to raise concerns, the field of hESC research deserves discussion that recognizes the limits of its terms and goes beyond simplistic and reductive conceptions of life and its beginnings.
[1] Congregation for the Doctrine of the Faith, Declaration on Procured Abortion Rome, 1974
[2] Yu, N. et al., New England Journal of Medicine 2002 346 (20), 1545-1552
[3] Kim, K. et al. Science 2004 306 (5702), 1780-1783
[4] Pearcy, M. et al. Science 2004 306 (5702), 1780-1783
[5] Nature 2007 447 (7148), 1031-1032
[2] This is problematic for three reasons: monozygotic or identical twins, chimerism and parthenogenesis. It is commonly known that identical twins have identical genes, which can be traced back to a single fertilization. If fertilization were used as the absolute and definitive beginning of the human individual it would leave room for only one person to be produced per fertilized egg. It is therefore unrealistic to use fertilization events to distinguish between human individuals.
Without looking to much into identical twins and chimerism I would like readers of the post to consider parthenogenesis and the moral and definitive issues which it presents.
Fertilisation events are also unnecessary for initiating development. Parthenogeneisis occurs when offspring are produced without the need for fertilisation. It has been observed in many species, including the Komodo dragon [3], and human eggs may be activated so that they develop parthenogenetically [4]. A collaborative effort between scientists from RUssia and the USA even managed to derive hESC lines from parthenogenetically activated eggs [5]. Although human embryos produced through parthenogeneisis have not yet survived to maturity, this development allows many objections to hESC research to be avoided, as fertilization is not involved
In principle, it ought to be possible for parthenogenetically-derived embryo to survive to maturity even though actually doing so would raise its own set of ethical concerns. However, the assumptions essential for vitalist objections to hESC research would require the adult human parthenote to not be considered an individual.
Just as an ant produced by parthenogenesis is an ant and a distinct member of the colony, the hypothetical human parthenote would also be a distinct human individual. The use of fertilization events as the absolute signifier of the beginning of human life would deny that the parthenote was an individual, which is false in the same self-evident fashion as the idea that identical twins are one individual.
This suggests that it is not appropriate to use fertilisation as a signifier for the beginning of a distinct human life and superior criteria should be developed.
Bioethical debates surrounding hESC research-should take into account that life is an ambiguous category and that suitable criteria for defining human individuality are not clear and simple. The approach of often religiously motivated vitalists fails to consider that science is unable to define human life with the precision required for thier arguments to work. As Nature editorial on the topic of synthetic biology remarks, “The formation of a new being is gradual, contingent and precarious…” While there should always be room for society to raise concerns, the field of hESC research deserves discussion that recognizes the limits of its terms and goes beyond simplistic and reductive conceptions of life and its beginnings.
[1] Congregation for the Doctrine of the Faith, Declaration on Procured Abortion Rome, 1974
[2] Yu, N. et al., New England Journal of Medicine 2002 346 (20), 1545-1552
[3] Kim, K. et al. Science 2004 306 (5702), 1780-1783
[4] Pearcy, M. et al. Science 2004 306 (5702), 1780-1783
[5] Nature 2007 447 (7148), 1031-1032
Code:
--- Partially recreated from
Admitting Ambiguity in the Embryonic Stem Cell Debate,* Shaun Khoo*
THE TRIPLE HELIX Oct 2008 pg19
I’m not a scientist.