[IWAR] BIO genetic rethink

From: 7Pillars Partners (partnersat_private)
Date: Mon Jan 19 1998 - 10:29:15 PST

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    Mixing the correct cellular soup for survival
          Copyright  1998 Nando.net
          Copyright  1998 Scripps Howard
       (January 19, 1998 00:13 a.m. EST http://www.nando.net) - Genes are the
       blueprint of life. Or perhaps not. Some embryologists -- scientists who
       study how a single fertilized egg develops -- are proposing an
       alternative theory: that genes are like building regulations, and it's
       growing cells that are the cutting edge of evolution.
       The idea has arisen out of some weird observations. A chimpanzee's
       are 99 percent the same as human genes. Even one-third of yeast genes
       have counterparts in humans.
       The curiosity is not how alike humans, chimpanzees and yeast must
       somehow be, but how different they actually are when they have so many
       genes in common.
       Another observation is that bacteria have evolved to live on just about
       any energy source. Some live in darkness, others in volcanic vents, and
       yet others on your teeth. Other living creatures are differently
       diverse. They give electric shocks, fly, or write symphonies, but their
       food is more or less the same.
       The two are linked because eating is about the biochemistry of energy.
       Fruit flies, which have many genes in common with humans, are
       genetically and biochemically similar to people. There are even
       biotechnology companies studying fruit fly genetics to help understand
       human biochemistry.
       What may have happened in prehistory is that bacteria came first and
       learned how to evolve biochemically. Two billion or so years later came
       other living creatures, which evolved through changing shape and
       John Gerhart of the University of California-Berkeley and Marc
       at Harvard Medical School have just published their summary of modern
       embryology, "Cells, Embryos and Evolution" (Blackwell Science, $69.95).
       It proposes that the vehicles for much of this second type of evolution
       are cells, and they are especially interested in one type called neural
       crest cells.
       These are cells that, during embryo development, can turn into any of
       enormous variety of more specialized ones. They include bones, bird
       beaks, human vocal cords, sense organs and blood vessels -- many of the
       distinguishing features of species.
       The job of neural crest cells is to explore. Blood vessels grow in
       patterns that are not determined by genes, and are often different in
       identical twins. Elk antlers, hummingbird beaks and elephants' trunks
       are all derived from neural crest cells.
       These cells have been studied for decades, but as Gerhart and Kirschner
       surveyed embryologists' work, increasingly informed by discoveries in
       more basic science such as molecular biology, it seemed that evolution
       itself depended on such cells.
       Is that enough to consider displacing genes from the center of the
       evolutionary universe? No. But it does begin to suggest genes should
       share the center stage with cells.
       To see how the two work together, let us take another look at how genes
       work, in the light of molecular and cell biology.
       Genes cause cells to make proteins such as insulin and hemoglobin.
       proteins make the body work.
       But genes don't make proteins all the time: they're switched on and off
       by what is happening around them. Insulin is made only when the
       conditions are right, perhaps when sugar is eaten. Every cell in your
       body has the same genes, but every gene has a set of switches which
       sure, for example, that your skin cells do not start making insulin.
       The switches work in response to the environment. But their environment
       is the cell. So genes and cells affect each other.
       Take deer antlers. Genes create a biochemical soup in which cells grow.
       During the animal's development, these cells "explore" new shapes. The
       size and shape of the antlers vary how the elk reacts to its
       environment: it may find it hard to eat leaves growing high, or easier
       to challenge rivals for the low-growing leaves.
       Either way, the food the animal eats affect where and when genes get
       switched on -- that is, they affect the biochemical soup.
       If the combination of genes and cells works well, the animal is
       successful and the soup's recipe is passed on to the next generation.
       What the embryologists are saying does not contradict traditional
       Darwinian evolution. Richard Dawkins, for example, has said the ability
       to evolve better is itself the result of evolution. Cells that evolve
       quickly would be one way of doing this.
       This also implies there can be different kinds of evolution, as in
       bacteria and their biochemical diversity, and animals and their shape
       diversity. Gerhart and Kirschner tentatively suggest there can be
       psychological evolution, too.
       Other scientists have suggested prehistoric man was what we would now
       describe as schizophrenic, given the evidence of remorse-free killings
       prompted by divine "voices", for example, described by Homer.
       Even this does not exclude genes, whose functioning is affected by the
       outside world. Schizophrenia appears to be related to a protein in the
       brain called dopamine. This is, of course, made by a gene.
       So genes tell cells what they can and cannot do. In return, cells call
       on the resources of genes to enable them to act. Perhaps the best
       analogy is that we are driving a car. The genes are the gears and
       while the cells are the bodywork and wheels. Lots of different car
       designs are possible.
       By DANIEL GREEN, The Financial Times

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