What Makes You Who You Are

The perennial debate about nature and evokewhich is the much potent shaper of the hu valet essence? is perennially rekindled. It fl ared up again in the London Observer of Feb. 11, 2001. REVEALED THE SECRET OF HUMAN BEHAVIOR, bear witness the banner headline. ENVIRONMENT, NOT GENES, KEY TO OUR ACTS. The source of the story was Craig Venter, the self-made man of genes who had built a private company to read the full order of the human genome in competition with an international consortium funded by taxes and charities.That sequencea string of 3 billion letters, composed in a four-letter alphabet, containing the complete recipe for building and running a human bewas to be published the very next day (the competition terminate in an arranged tie). The first analysis of it had revealed that there were in effect(p) 30,000 genes in it, not the 100,000 that many had been estimating until a few months before. Details had already been circulated to journalists nether embargo. But Vent er, by speaking to a reporter at a biotechnology conference in France on Feb. , had effectively broken the embargo. non for the first time in the increasingly bitter rivalry oer the genome project, Venters version of the story would hit the headlines before his rivals. We simply do not have enough genes for this idea of biological determinism to be right, Venter told the Observer. The grand diversity of the human species is not hard-wired in our genetic code. Our environments are critical. In truth, the design of human genes changed nothing.Venters remarks concealed two whopping nonsequiturs that fewer genes implied more environmental influences and that 30,000 genes were too few to explain human nature, whereas 100,000 would have been enough. As one scientist put it to me a few weeks later, just 33 genes, from each one coming in two varieties (on or off), would be enough to fall in every human being in the world unique. There are more than 10 billion combinations that could c ome from flipping a coin 33 times, so 30,000 does not seem such a small number after all.Besides, if fewer genes meant more free will, fruit flies would be freer than we are, bacteria freer still and viruses the John Stuart Mill of biology. Fortunately, there was no lack to reassure the population with such sophisticated calculations. People did not outcry at the humiliating news that our genome has only about twice as many genes as a worms. Nothing had been hung on the number 100,000, which was just a bad guess. But the human genome projectand the decades of research that preceded itdid staff office a much more nuanced understanding of how genes work.In the early days, scientists detailed how genes encode the various proteins that make up the cells in our bodies. Their more sophisticated and ultimately more satisfying discoverythat gene expression can be modified by experiencehas been gradually emerging since the 1980s. Only nowadays is it dawning on scientists what a big and general idea it implies that learn itself consists of nothing more than switching genes on and off. The more we lift the palpebra on the genome, the more vulnerable to experience genes appear to be.