Recent research has shown that intelligent men produce better quality sperm. The research was carried out to asses the idea that intelligence is favored by natural selection.

Research team at King's College London analysed data from 4,462 former US soldiers who had served during the Vietnam War. The soldiers took several intelligence tests and underwent a detailed medical examination. Semen samples were also provided by 425 soldiers. Data analysis showed small but statistically significant correlation between intelligence and three measures of sperm quality.

Lead researcher, Ms Rosalind Arden said: "We found a small positive relationship: brighter men had better sperm."

She added that research doesn't say that under modern conditions intelligent men are going to have more children.

She said that the improvement in semen quality with intelligence observed in this paper is small and therefore it is unlikely to have a big impact on the ability of men of different intelligences to conceive. The effect was small so is unlikely to be relevant to individuals.

Ms Arden said: "This does not mean that men who prefer Play-Doh to Plato always have poor sperm: the relationship we found was marginal."