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New page: Lactose intolerance is a condition where individuals cannot digest lactose, a sugar found in milk. When a lactose intolerant individual injests of milk, he or she will get a s...
Lactose intolerance is a condition where individuals cannot digest [[lactose]], a [[sugar]] found in [[milk]]. When a lactose intolerant individual injests of milk, he or she will get a stomachache. Other symptons include cramps and bloating. Such individuals do not produce an [[enzyme]] called [[lactase]] that breaks down lactose after weaning.
The proportion of lactose intolerant individuals varies by region on the planet. 99% of [[China|Chinese]] are lactose intolerant, whereas only 10% of [[United States|Americans]] are. Recent research indicates that lactose intolerance is high where [[cow]]s were not domesticated. This caused a gene to be permanently switched on, and natural selection favored a continued production of lactase during adulthood.
[http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/]
[http://evolution.berkeley.edu/evolibrary/news/070401_lactose]
The proportion of lactose intolerant individuals varies by region on the planet. 99% of [[China|Chinese]] are lactose intolerant, whereas only 10% of [[United States|Americans]] are. Recent research indicates that lactose intolerance is high where [[cow]]s were not domesticated. This caused a gene to be permanently switched on, and natural selection favored a continued production of lactase during adulthood.
[http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/]
[http://evolution.berkeley.edu/evolibrary/news/070401_lactose]