Scientists have found more than 500 genes that account for variations across human populations including skin colour, height and vulnerability to disease, according to a new study.

By comparing millions of fragments of genetic code from individuals in four groups - from Nigeria, China, Japan and northwest Europe - researchers say that natural selection has played a key role in these differences.

The findings, which are published online ahead of print in the journal Nature Genetics, hold particular promise for understanding the genetic underpinning of certain diseases.

The researchers, led by Dr Lluis Quintana-Murci of France's National Centre for Scientific Research pinpoints, for example, the tiny genetic variation in the CR1 gene that has made 85% of Africans highly resistant to malaria.

Once the specific bit of genetic code responsible for a predisposition to a certain illness or condition has been identified, scientists can then set about trying to find a drug to treat it.