Scientists are not interested in facts. What they like is ignorance. They mine it, eat it, attack it – choose the metaphor you prefer – and in the process they keep discovering more ignorance. Every answer leads to a set of new questions. The past few years have seen a once-in-an-aeon explosion of new knowledge about the human body and mind, as a consequence of our becoming the first creature in four billion years to read our own genetic recipe. Even more, they have seen an explosion of newly discovered ignorance.
Most people now know the humiliating news from the Human Genome Project that we have the same number of genes as a mouse. There is no special set of 50,000 genes for making human brains, as was being seriously mooted just a decade ago. The news keeps getting more deflating, because even the recent estimate of 30,000 human genes looks like an overestimate. The current betting is for fewer than 25,000, which is barely twice as many as a fruit-fly, a mere 6,000 more than a microscopic worm, 2,000 fewer than a mustard weed and 15,000 fewer than a rice plant. Dethronement on this scale has not happened since Copernicus took us out of the centre of the solar system.
Consolingly, the first few genes we have looked at are revealing some profound insights. The ASPM gene seems to control brain size; the FOXP2 gene is apparently a key to learning language; the AVPR1A gene may partly explain the ability to fall in love; the APOE gene can help to predict Alzheimer’s; the CREB gene is part of the mechanism of memory; the DAF2 gene controls aging (at least in worms); the MAOA gene affects our response to child abuse; the KAL1 gene affects penis size, libido and sense of smell; the SRY gene makes males male; and so on.