rmwilliamsll said:
one of the pieces of scientific evidence that interests me in the contra-ID discussion is chimeras. ID is directed at the evolutionary idea of "the directionlessness of evolution", positing instead a designer of some type. The argument against this designer is that people do not design the way life is, in particular, the careful dual nested hierarchical structure.
software design is arguably the best example of how people reuse and recycle good ideas (bad ideas as well, but that is not the point *grin*). Thus effectively constantly creating chimeras.
well here is a nice accessible to the average non-scientific type article on chimeras:
http://www.msnbc.msn.com/id/6534243/
As you read the article, note carefully how naturally our minds interact with the idea. We have it in ancient literature, modern movies (check out predator vs aliens *grin), in lots of areas.
Chimeras have deep philosophical implications. HEre are some things I have in my database. MZ is multizygotic. No one should assume that I am arguing for a naturalistic world. What I am doing is saying that we should deal with the world as it is, not as we want or wish it to be. The cases below do challenge our viewpoints. With each, ask, where is the soul?
[box]There is a well-known case
in 1949 of such a 'foetus-in-foetu', in which five fetuses were
removed from the brain of an infant girl in Philadelphia; several
less spectacular cases have been reported since, including a six-
pound foetus round during the autopsy of an elderly man. These
events probably accidents of timing during early pregnancy.
Identical twinning is thought to occur on or before the fourteenth
day after conception. If the division happens early in that cycle,
the embryos will be in separate placentas, like nearly all
fraternal twins By the end of the fourth day, the chorion, which
is the outer placental membrane, will have formed, and if the
zygote divides after that time, as is the case with two-thirds of
MZ twins, they develop in a single placenta. If the division
occurs between the fifth and the eight day, the twins will still
be encased in separate amniotic sacs, but if they divide after the
eighth day there will be nothing between them. Half of these late-
splitting twins die, often strangling in each others umbilical
cords. It is thought that by the twelfth day the division is
likely to be incomplete, resulting in conjoined or Siamese twins,
which occur in abut one out of 400 MZ births, foetus-in-foetu, and
teratomas. These are, however, only theories. One can also make
the case that the twinning process got stuck at the beginning and
never advanced. These abnormalities are far more prevalent in
girls than in boys, since male twins (like all boys) are more
likely to miscarry." Lawrence Wright, Twins, (London: Phoenix
Books, 1997), p. 78-79[/box]
[box]chimeras the soul can't be formed as the result of sperm/egg
union. MZ twins are one fertilization but two souls
Chimeras are two fertilizations in one body and one soul
"Charles Boklage believes that most malformed children who
were born as singletons actually may be the product of twin
pregnancies. This may also be true of left-handers, who are more
common among twins. He cites another interesting phenomenon,
which, although it has rarely been detected, may not be at all
uncommon. 'It is possible that I am twins. By that I mean that two
different embryos went together to make one body. We know that
occasionally happens, but it is almost never detected except in
the blood banks. I think it is actually much more common than
that. I can tell you with complete certainty that some of us are
twins who are walking around in a single body.' Such a creature is
called a chimera, after they mythological Greek monster that had
the head of a lion, the body of a goat, and the tail of a serpent.
Chimeras are easily produced in the laboratory. 'We've had
thousands of experiments with rats and mice in which we take part
of a mouse embryo and stick it in a rat embryo,' says Boklage.
'We've done it between sexes and between species. They never make
twins. They always fuse into single embryos and come out part rat,
part mouse, part male, part female, part sheep, part goat. The
forces involved in embryogenesis simply overpower the differences
in their origins. I'm sure there are creatures too far apart to
put together, like a mouse and a chicken. But when these events
occur in human development, it simply goes on.' Chimeras sometimes
happen in nature when littermates fuse together. The fact that
this happens in humans was only discovered when donors in blood
banks were found to be carrying two different blood types; it
could mean that fraternal twins merged in the womb. Most human
chimeras re to some extent hermaphrodites, with ambiguous
genitalia. Of course, there is no way to discover if identical
twins have merged, since their genes and blood types are the same.
In these cases, the twins don't vanish, they amalgamate."
"When an infant twin girl, year and a half old, recently
appeared in the Department of Paediatrics at the British Columbia
Children's Hospital in Vancouver suffering from chronic lung
infections, Judith Hall routinely checked for cystic fibrosis. By
analyzing the chloride level in her sweat, Dr Hall got a positive
diagnosis. 'We then decided it was time to check the twin,' says
Hall. As it happens, when these twins were born their obstetrician
carefully examined the membranes of the placenta to determine
their zygosity. There was a single chorionic sac, so the doctor
assumed that the girls must be identical. And yet, when Hall
tested the eighteen-month-old twin for cystic fibrosis, there was
no sigh of the disease. 'We then decided to do blood studies,
looking for common mutations that occur in cystic fibrosisand
they weren't there in either twin! So we scratched our heads. We
then decided to take a bit of skin, and when we did that, the kid
with cystic fibrosis had the common mutations and the other
didn't.' This was a terrific muddle. The other twin was not even a
carrier of cystic fibrosisno evidence of the gene at all. DNA
tests showed that the girls were not, in fact, MZ twins.
Apparently they were the result of two separate acts of
conception, but the zygotes implanted so close to each other in
the uterus that the placentas fused. Further testing showed that
the diseased twin was carrying the blood of the healthy twin. They
had evidently shared the same circulation in the womb, which is
common among identicals, but rare among fraternals. 'They were two
separate creatures, but they shared their blood in the placenta at
such an early age that one twin actually took over for the
abnormal twin, so its blood was healthy but the rest of its body
had cystic fibrosis,' says Hall.' That's a chimera.' "Lawrence
Wright, Twins, (London: Phoenix Books, 1997), p. 82-84[/box]
[box] ""If most of the cells of the blastocyst give rise to the
trophoblast, exactly how many cells actually form the embryo? ONe
way to answer this question is to produce ALLOPHENIC MICE.
Allophenic mice are the result of two early-cleavage (usually 4- or
8-cell) embryos that have been aggregated together to form a
composite embryo. As shown in Figure 28, the zonae pellucidae of two
genetically different embryos are removed and the embryos brought
together to form a common blastocyst. These prepared blastocysts are
implanted into the uterus of the foster mother. When they are born,
the allophenic offspring have some cells from each embryo. This is
readily seen when the aggregated blastomeres come from mouse strains
that differe in their coat colors.""~Scott F. Gilbert, Developmental
Biology (Sunderland: Sinauer Assoc. Inc., 1991), p. 95[/box]
Where is the soul?
[box]The experimental data of Mintz (1970) are that 73 percent of the
double embryos yield allophenic mice, thus suggesting that three
blastomeres of the blastocyst produce the entire embryo. Markert and
Petters (1978) have hown that three early 8-cell embryos can unite to
form a common compacted morula and that the resulting mouse can hav
the coat colors of the three different strains. Therefore, while i
is not certain that three is the absolute number of blastomeres tha
form the embryo, we can be fairly certain that the number is not
much greater and that most of the cells of the blastocyst never
contribute to the adult organism.""~Scott F. Gilbert, Developmental
Biology (Sunderland: Sinauer Assoc. Inc., 1991), p. 95-96[/box]
There is one mother I cant find the quote now, who needed a transplant and when they did the blood test, they found she couldn't have been the mother of any of her 3 children. It seems that she is a chimera and had absorbed a twin. Her blood is from her absorbed fraternal twin and her ovaries are from the other fetus--I guess I mean her. It gets a bit confusing.
edited to add: I finally found the documentation for this last case. It can be found in New Scientist 15 Nov 2003. She couldn't have been the mother of 2 of her 3 children according to the test. Two embryos had fused to form one person. This is an issue we must deal with.
