9 DECEMBER 2006, Page 28

From Mark Austin Sir: While I agree with the thrust

of Allister Heath’s article, he has inadvertently made a statistical error in assuming (or giving the impression of assuming) that an average lifespan of, say, 30 in the past means that most died at about that age. In fact, the figures are distorted by a very high rate of infant mortality. If we assume 50 per cent infant mortality before the age of one in the Middle Ages (a not unreasonable assumption), the average age at death of the remainder would be 59, with relatively low mortality rates at the age of 30.

Similarly, much of the improvement in life expectancy in the Third World has come about by falls in infant and maternal deaths.

Mark Austin

Morden, Surrey