Intellectual evolution

Les Ebdon argues that "Older isn't always wiser" (29 January). That may be appropriate in some disciplines, but there are some striking exceptions, especially in biology and with holistic rather than reductionist approaches. The one appearing in the media almost daily as the 200th anniversary of his birth approaches is Charles Darwin, who published his seminal work on evolution at the age of 50. Another example is James Lovelock, who published his Gaia hypothesis in his mid-50s.

Peter Kettlewell, Shrewsbury.