halfgaar wrote:Well, because they kept drinking milk, their bodies adapted to it.
BTW, I've been told that hard cheese doesn't even contain lactose...
do you think people adapt to milk or over the generations the mutation that allows one to digest lactose was helpful for surviving and over time the group of people acquired this trait
quote from wikipedia:
http://en.wikipedia.org/wiki/Lactose_intolerance
"Lactase biology
The normal mammalian condition is for the young of a species to experience reduced lactase production at the end of the weaning period (a species-specific length of time). In non dairy consuming societies, lactase production usually drops about 90% during the first four years of life, although the exact drop over time varies widely.[8]. The majority of the world's human population follows this trend, with the lactase producing genes largely inactivated in adulthood.[9][1]
However, certain human populations have a mutation on chromosome 2 which eliminates the shutdown in lactase production, making it possible for members of these populations to continue consumption of fresh milk and other dairy products throughout their lives without difficulty. This appears to be an evolutionarily recent adaptation to dairy consumption, and has occurred independently in both northern Europe and east Africa in populations with a historically pastoral lifestyle.[9] Lactase persistence, allowing lactose digestion to continue into adulthood, is a dominant allele, making lactose intolerance a recessive genetic trait.
Some cultures, such as that of Japan, where dairy consumption has been on the increase, demonstrate a lower prevalence of lactose intolerance in spite of a genetic predisposition[10].
Pathological lactose intolerance can be caused by Coeliac disease, which damages the villi in the small intestine that produce lactase. This lactose intolerance is temporary. Lactose intolerance associated with coeliac disease ceases after the patient has been on a gluten-free diet long enough for the villi to recover[citation needed].
Certain people who report problems with consuming lactose are not actually lactose intolerant. In a study of 323 Sicilian adults, Carroccio et al. (1998) found only 4% were both lactose intolerant and lactose maldigesters, while 32.2% were lactose maldigesters but did not test as lactose intolerant. However, Burgio et al. (1984) found that 72% of 100 Sicilians were lactose intolerant in their study and 106 of 208 northern Italians (i.e., 51%) were lactose intolerant."
