Juggs asks:
Why aren't they human beings?
"I cannot see any intrinsic, morally significant difference between a mature skin cell, the totipotent stem cell derived from it, and a fertilized egg," writes Savulescu. "They are all cells which could give rise to a person if certain conditions obtained.... If all our cells could be persons, then we cannot appeal to the fact that an embryo could be a person to justify the special treatment we give it."
Remember, Juggs, researchers were recently able to flip a few genetic switches and "turn" a skin cell into a totipotent cell.
That means every cell in your body has the potential to become a zygote (without the benefit of having its nucleus injected into an ovum).
Recently, murine fibroblasts have been reprogrammed directly to pluripotency by ectopic expression of four transcription factors (Oct4, Sox2, Klf4 and Myc) to yield induced pluripotent stem (iPS) cells. Using these same factors, we have derived iPS cells from fetal, neonatal and adult human primary cells, including dermal fibroblasts isolated from a skin biopsy of a healthy research subject. Human iPS cells resemble embryonic stem cells in morphology and gene expression and in the capacity to form teratomas in immune-deficient mice. These data demonstrate that defined factors can reprogram human cells to pluripotency, and establish a method whereby patient-specific cells might be established in culture.
Reprogramming of human somatic cells to pluripotency with defined factors
Nature (23 Dec 2007)
The difference between what they are and what they could become is the environment in which their DNA is found. Thus, the mere existence of human DNA in a cell cannot be the source of a relevant moral difference.
Because it is logically ... possible for each of your body's cells to become your twin. Each skin cell, each neuron, each liver cell is potentially a person.
All quotes not otherwise attributed are from:
Page not found - Reason.com
You have the problem, Juggs.
Not me.
Since I don't consider a cell or a group of cells "human", I have no problem
at all declaring a zygote a wad of undifferentiated cells and nothing more.
Because
my definition of human = a group of cells with genetic input and the appropriate biochemical pathways.
Using
your definition, each of
your cells is a "child".
And you've got bigger problems on the horizon, my friend.
Another option being pursued by researchers is the generation of animals that produce human gametes. To date, it has been demonstrated that mice containing a human ovarian xenotransplant can produce human oocytes (Gook et al. 2003). Human gametes could in theory also be made by chimaeric animals produced by injecting human embryonic stem cells into animal blastocysts. The use of gametes produced by grafted or chimaeric animals in fertilization theoretically could result in blastocysts that are capable of implantation and forming a viable pregnancy.
http://www.nhmrc.gov.au/...nformation/_files/humanembryo.pdf
Animal produced human gametes that are then activated via SCNT or parthenogenesis = "child" in your book?
Another possibility is an individual that contains cells from different species. Injection of genetically altered mouse embryonic stem cell lines into mouse blastocysts is used by researchers to generate transgenic and knockout mice. (However) the developmental potential of chimeras created by injecting human embryonic stem cells into a blastocyst from a different species or by injecting non-human embryonic stem cells into a human blastocyst (DeWitt, 2002) is unknown.
http://www.nhmrc.gov.au/...nformation/_files/humanembryo.pdf
A chimera = "child"? After all, it contains human DNA.
And that's just the tip of the iceberg:
Emerging technologies(1) Cloning by embryo splitting
(2) SCNT”human somatic cell and human oocyte
(3) Heterologous nuclear transfer”hES cell nucleus and human oocyte
(4) Pronuclear transplantation”transfer of pronuclei from fertilized human oocyte to enucleated dor human oocyte
(5) Parthenogenesis”human oocyte activation
(6) Chimaera”generated by aggregation of individual viable blastomeres obtained from nonviable embryos
(7) SCNT”human somatic cell and enucleated animal oocyte
(8) Fertilization”mouse sperm generated in vitro from differentiating mES cells
(9) Gygenesis ” as for pronuclear transplantation but using two maternal pronuclei
(10) Androgenesis ” as for pronuclear transplantation but using two paternal pronuclei
(11) SCNT”mouse somatic cell genetically altered to remove implantation potential and enucleated mouse oocyte
(human material involved)
(12) Chimaera”injection of mouse blastocyst with mES cells
(human material involved)
(13) Fertilization”human gametes generated in vitro from differentiating hES cells
(14) Fertilization”human gametes produced in vitro
(15) Fertilization”human oocytes produced by animals containing human ovarian tissue grafts fertilized with human sperm
(16) SCNT”human somatic cell genetically altered to remove implantation potential and enucleated human oocyte
(or oocyte generated in vitro from differentiating hES cells)
(17) SCNT”human somatic cell genetically altered to remove implantation potential and enucleated animal oocyte
(18) Chimera”injection of hES cells into animal blastocyst
(19) Chimera”injection of animal ES cells into human blastocyst
Yep. You're the one the problem, chum.
You've chosen to define human as "a piece of DNA".
Not me.
ABE:
If we are just a mass of cells, then what is the difference between you and a blastocyst, zygote, or a fetus?
You do realize, of course, that I could synthesize a lump of 10 trillion cells (estimated # of cells/body), all of human origin, and that would not be a "human", right?
My definition includes genetic input
and the appropriate biochemical pathways.
You conveniently ignored half of my definition.
Edited by molbiogirl, : sp
Edited by molbiogirl, : addn
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