With that kind of information available in profusion, you can tell that this is not just a serious exposition of scientific theory, but a collector's scrapbook. Chris McManus, Professor of Psychology and Medical Education at University College, London, has devoted his career to "handedness and lateralization", and his files are full of curious observations. Among them are many items of left-hander lore that he is at pains to demolish, such as the old-wives' claims that left-handers are more creative than the rest of us, or die younger, or that because the Gaelic root of their name means "awkward", people called Kerr and Carr are more predominantly left-handed than the population at large.

But in us, the neo-Darwinian mechanism seems logjammed. Some genetic variants are being lost, as small tribal groups continue to die out; and others are constantly gained by mutations, some of which persist. There are fluctuations: genes that confer resistance to Aids are gaining ground in Africa, for instance, while Kenyans are currently breeding faster than Italians, so any genetic variants that are peculiar to either group must be increasing or falling. But the permanent losses of genes through extinction of minorities are small compared to the whole pool, and while the particular genes of Kenyans may wax in one century, they may wane in another. Most importantly, there is no consistent pressure to push our gene pool in any particular direction. Nobel prize-winners and professional basketball players are lauded, but do not typically leave more offspring than the ordinary Joe. Infant mortality is still high in some societies but, in genetic terms, it strikes randomly because the poor are not genetically distinct.

Voyager 1's original attitude-control system showed slowly increasing signs of trouble in the past two years, said Tim Hogle, a flight-team engineer. Diagnostics pointed to an electronic component that takes analog signals from position-sensing devices and converts them into digital values for an onboard computer. Because of the system's design, switching to that component's backup also meant activating the backup Sun sensor and star tracker, which provide the reference points for the spacecraft's orientation in space.