HUMANS are accumulating mutations at a remarkably high rate, two biologists
in Britain have found. The finding has led to speculation that modern healthcare
is allowing harmful mutations to accumulate faster than they would
Biologists have long suspected that human genes, like those of other
hominids, are particularly susceptible to mutations. Adam Eyre-Walker of the
University of Sussex and Peter Keightley of the University of Edinburgh compared
mutation rates in humans with those of chimpanzees and gorillas (Nature,
vol 397, p 344). They confirmed that Homo sapiens has a high rate,
with 4.2 amino acid-altering mutations each generation.
Keightley believes that around a third of these mutations are sufficiently
harmful that they are removed by natural selection—offspring that inherit
them are unlikely to survive to reproductive age.
The researchers point out that although harmful mutations are eliminated,
slightly deleterious mutations may survive. Moreover, the standard of living
enjoyed by people in developed nations may encourage these mutations to
accumulate at a higher rate than they would in a more demanding environment.
James Crow of the University of Wisconsin suggests that modern healthcare
might mean that such people would have a lower chance of surviving in more