A man's income may be partly determined by the speed at which he grew in the first year of life, scientists are claiming.

　　Findings from a study of 4,630 Finnish men showed that those who were shorter than average at the age of one earned significantly less than others in their peer group. They were also less likely to attain a high level of education. The result was striking and held true irrespective of social background, said the researchers.

　　They believe slower growth during the crucial brain development period in an infant's first year may impair an individual's mental abilities. This would lead to disadvantages throughout life, including poorer performance in school and a lower income.

　　Professor David Barker, from the University of Southampton, who co-led the study, said: "What we have shown is that boys who don't grow so well in the first year of life do less well at school, and 50 years on are earning less money, than those who grew faster. The differences are significant irrespective of social origins. Something is happening to the brain that's pretty much worked out in the first year of life, and it's very amazing to be able to see it."