A survey of the human genetic code has shown that our resistance to malaria, diabetes and other diseases is changing in response to our environment.
We already know that in the past, people developed lighter skins when living in parts of the world with less sunlight.
We now also know that several traits are sometimes linked to a single gene. For instance, when people in the Far East evolved a different version of the EDAR gene to sweat differently, the same gene gave them much denser hair and changed their teeth too; the effect has been called "hitchhiking".
Genes that protect against disease are also evolving. The CR1 gene helps cut the severity of malaria attacks and is now present in 8 out of 10 Africans, but is absent elsewhere.
Several genes, such as ENPP1, are involved in the regulation of insulin and in metabolic syndrome (a combination of diabetes and obesity). These genes are present in 9 out of 10 non-Africans but fewer in Africans (suggesting they have not yet adapted to an American lifestyle), which might explain why African Americans are especially at risk of obesity and high blood pressure.
Source: Roger Highfield: Humans are evolving to resist disease. The Telegraph 5 Feb. 2008
