| Tuesday, June 28, 2005 |
| WHY DON'T IDENTICAL TWINS HAVE IDENTICAL FINGERPRINTS? |
The strange thing about identical twins is not the fact that they're identical, but that they're not, actually, identical. (Another victory for concise writing). Sure, sometimes they freak you out with that dress like Doublemint look, but eventually you can tell which one is Gilbert and which one is Philbert.
"Identical twins are identical only in the sense that they have identical genomes". says Thomas Bouchard, a psychologist at the Unviersity of Minnesota who is famous for his work on twins, separated at birth and raised apart (e.g. Al Gore and Vlark Kent).
So if their genomes (genetic codes) are the same -- notwithstading the occasional spontaneous genetic mutation -- why are't they truly identical? Bouchard answers. "There is what is called developmental noise".
Developmental noise ! An important phrase. (Gubs n'Roses is developmental noise for teenagers). Yhe termsrefers to anything in the environment that affects the way the genetic instructions are translated into an actual living thing. For example, twin embryos don't have equal blood supplies; one embryp grows larger, and so by birth there is a pronounced difference in the weight of the twins.
Development noise probably has an effect at tan even more basic level -- the translation of the DNA code into a biological constrcution project that results in, say, a fingerprint. The fingerprints of identical twins are quite similar, enough to be an indication that twins are idnetical and not fraternal. Bu there are subtle differences that are observable even when theya re still embryos.
The DNA is a precise set of instructuon, but the secretion of growth and hormones and so forth is a matter of approximation, notes Paul Berg, professor of biochemistry at Stanford and author of Genes and Genomes. What the genes say is not a s important as how they are "read", he says. "Minor variations in the environment of two cells could easily influence hos the identical genes in those two cells are read out". he explains.
It's kind of like whispering "fire hose" into someone's ear and asking him to pass it down the line: A dozen people later, the phrase has turned into "nose hairs".
(abstracted from the book:WHY THINGS ARE AND WHY THINGS AREN'T by: Joecl Achenback) |
| posted by infraternam meam @ 1:52 AM |
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Name: infraternam meam
Home: Chicago, United States
About Me: I am now at the prime of my life
and have been married for the past 25 years.
Sickly at times, but wants to see the elixir vita,
so that I will be able to see my grandchildren from my two boys.
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