Only now, more than a century after the publication of The Origin of Species, are we finally getting to grips with Darwin's blinding insight. Life forms are not the reassuringly changeless entities that plodded two by two into the Ark. All, including our own, are merely provisional. Tirelessly reworked by nature, they are now manipulated by our own, more violently ambitious, hands.
Having assembled crops that know no pests, we now routinely inject bits of one beast into another to fashion composites. Next, apparently, we can expect super-babies, immune not just to disease, but to stupidity and ugliness as well. And all only six years after Dolly the Sheep set us on course for this Frankenstein future. Except that Dolly's creators were not quite the pioneers that they may have seemed at the time.
The full import of Darwin's original message wasn't lost on all his contemporaries. By the 1860s, an Austrian abbot called Gregor Mendel was making statistical analyses of the impact of hybridisation on peas in his monastery garden. His work, at first ignored, was rediscovered at the turn of the last century. By the 1920s, it was fuelling an obsessive race to construct the first genetically engineered creature. But the prize so frenziedly sought in this forgotten contest was no lion-tiger, 50-gallon-a-day milch-cow or super-human - it was a red canary.
In its day, the humble canary was the currency of princes, worth more than its weight in gold and exported in millions. Its voice was its fortune, but it laboured under a disadvantage: in its natural state, its appearance is dingy, greenish and not at all what humanity requires from an operatic songster. It took a century of meticulous breeding to turn captive canaries canary-yellow. But yellow wasn't good enough. Why couldn't a canary be crimson-red?
Artificial evolution seemed to hold out the promise of achieving the required make-over. Other species of bird were indeed brilliant crimson: Venezuela's red siskin, for example. Get a few of the latter's genes into a canary and you ought to be on your way.
Nowadays, monster-makers can easily intrude DNA from one creature into another on the back of virus or bacterial vectors. In the 1920s, the only way of getting genes from a siskin into a canary was to persuade specimens of each to copulate. Then, if a cross was created in which the siskin's colour was dominant, and which was also fertile, it was necessary to back-cross it repeatedly with canaries until, of the siskin genes, only the one responsible for red feathers remained.
This enterprise, to which thousands of people devoted their lives, is chronicled in Tim Birkhead's book. His expert grasp of the science involved is to be expected from a professor of behaviour and evolution. What is more surprising is his capacity to make it not just comprehensible, but fascinating, by making his own genetic cross of science, philosophy, history, sociology and narrative.
The centre of the pre-war bird-fancying world was Germany, and the canary breeders' obsession with Mendelian genetics became entangled with the Nazis' enthusiasm for purifying the master-race. The most energetic of all the red canary chasers, a schoolteacher called Hans Duncker, became director of Bremen's Racial Hygiene Society and an effective populariser of eugenic ideas. Yet in spite of the energy invested in them, both the human and avian projects failed.
The reason ought to resonate with our own age, now becoming as genetics-obsessed as Duncker's. It emerged that genes, potent as they may be, aren't everything. On their own, they couldn't even turn canaries red. Bird colour, it was finally realised, depended not just on inheritance, but also on environment.
Canary-siskin hybrids refused to progress beyond a dull coppery colour. Then, an American breeder called Charles Bennett heard that four women who, for some reason, had eaten four pounds of carrots a week for seven months turned bright orange. In 1946, Bennett tried feeding carrots to some of his own coppery birds. Hey presto, they turned red. Yet no amount of carrots could redden a pure-bred canary. Nature and nurture could only work together.
The long struggle was over. Today there are probably more red canaries in captivity than there are red siskins left in the wild, after canary breeders' depredations on the latter. Even so, red canaries are still not as red as red siskins. Why not? Fanciers have their theories, but they do not know for sure. After 400 years of meddling, they have penetrated but a few of nature's secrets. Today's more audacious but less practised genetic adventurers might usefully bear that in mind.