Movement of humans between populations may have helped to increase average height by bringing together genes from different sources
Sir, That the average height of man has increased by four inches over the past century (report, Sept 2) must be a result of many interacting factors in populations.
In addition to the possible factors you listed it must be highly likely that the greater movement of humans both within and between populations must have played a not insignificant part in this response by bringing together genes from widely different sources and therein resulting in an escape from previously relatively closed communities with various degrees of inbreeding depression.
In animal breeding the parallel would be termed “hybrid vigour”.
Dr Tony Lawrenc