From: mcdonald@kestrel.edu (Jim McDonald)
Newsgroups: alt.rush-limbaugh,talk.abortion
Subject: Re: The origin of individual human beings
Date: 10 Oct 92 02:16:30 GMT
Distribution: usa
Organization: Kestrel Institute, Palo Alto, CA


In article <Oct05.202401.52295@yuma.ACNS.ColoState.EDU>, sa114984@longs.lance.colostate.edu (Steven Arnold) writes:
|> In article <1b_p5lc.ray@netcom.com>, ray@netcom.com (Ray Fischer) writes:
|> |> Kurt Ludwick <KEL111@psuvm.psu.edu> writes ...
|> |> > kcochran@nyx.cs.du.edu (Keith "Justified And Ancient" Cochran) says:
|> |> >
|> |> >>>Certainly Brian, I look to the scientific experts and follow their
|> |> >>>opinion on this subject.  While it is by no means a consensus, a
|> |> >>>large majority of embryologists agree that human life begins at
|> |> >>>conception.
|> |> >
|> |> >>Human life began millions, possibly billions of years ago.  Please subscribe
|> |> >>to the newsgroup talk.origins for more details.
|> |> >
|> |> >I don't understand why that question always gets this answer.  I understand
|> |> >the point, but why not answer the -intended- question?  Is this just another
|> |> >semantics argument, or what?
|> |> 
|> |> Because saying that embryologists say that a human life begins at conception
|> |> isn't particularly useful.  It is saying that a human life is that which
|> |> begins at conception because a human life begins at conception.  If you're
|> |> just going to _define_ a human life to begin at conception, then you might
|> |> _define_ with just as much validity a human life to begin at birth.
|> 
|> 	Conception is the first time that a human individual is
|> created, an individual who will, if not killed, eventually grow
|> into an adult human.  At no time prior to conception is this the
|> case, and at no time after.  BTW, if you have a documented
|> statement from a reputable embryologist who says that a human
|> individual is created at any time OTHER than at conception, I'd
|> like to see your source.  In all my time on this net so far, I
|> haven't seen any such thing.
|> 
|> Steve

Unless you have a truely bizarre notion of what constitutes a human individual,  there
is clear scientific evidence that some indivuals are created well after conception, by the
merger of multiple zygotes or embryos.  They are refered to as chimeras, and in some 
sense are the opposite of identical twins.  There are documented people whose left and
right sides come from different zygotes, and other people whose ovaries come from one
zygote while the rest of the body comes from another.

A very cursory 5 minute dash to the library turned up this reference:

Chapter 7, "Human Chimeras",  by Patricia Tippett of the MRC Blood Group Unit , 
University College London, London England, from the book Chimeras in Developmental 
Biology,  1984, Academic Press, London.

Some typical quotes from that chapter:

  Anderson et al (1951) distinguished a chimera, an organism whose cells derive from
  two or more zygotic lineages, from a mosaic, whose cells derive from a single zygote
  lineage.  These definitions are used by all biologists.  Human chimeras may be 
  artificial (induced) or natural (spontaneous); natural chimeras include both twin(sic),
  which have two populations in their blood only, and dispermic chimeras (Race and
  Sanger, 1975).  

  Dispermic chimeras result from the fertilisation by two sperm of two maternal nuclei,
  the fusion of the two zygotes, and their growth into one body.  McLaren (1976) calls the
  state  ``primary chimerism,'' and it has also been called generalized tissue mosaicism,
  whole-body chimerism, and tetragametic chimerism.

  Tippett (1983) added 12 more dispermic chimeras to those reported by Race and Sanger
  (1975).  These rare people are either hermaphrodites or intersexes, and/or have two cell
  lines or a mixture of skin colors showing that their chimerism is not limited to blood.

Any competent embryologist (and probably most incompetent ones) are fully aware of
mosiacs and chimeras, so the quotes above about "most embryologistics" are highly
suspect.  Please document even *one* embryologist who holds the opinion you cited.

If you assume persons are created at conception, then you will have a hard time 
explaining how some woman's ovary is not a person, and how the left haft of someone
else is a different person from their right half, etc.

I hope this puts an end to the repetitive nonsense posted here about  zygotes going on
to become people.  Sometimes they go on to become ovaries, collections of white blood
cells, left sides of people, etc.   (But I won't hold my breath.)
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