The most significant international event of the year 2000 was, almost certainly, neither political nor military, but scientific - the announcement, in June, that the human genome had been almost totally decoded. Future generations may well see this as a major turning point, opening the way to radical changes in diagnosis, prognosis, and medical treatment. Often compared with the space programme, this vast enterprise still generates misgivings: this new power, which human beings now have, to modify the genetic heritage of living creatures raises fundamentally new ethical questions - and...