Early man 'couldn't stomach milk'

[Guest guest]

Early man 'couldn't stomach milk'

A drink of milk was off the menu for Europeans until only a few

thousand years ago, say researchers from London.

Analysis of Neolithic remains, in Proceedings of the National Academy

of Sciences, suggests no European adults could digest the drink at

that time.

University College London scientists say that the rapid spread of a

gene which lets us reap the benefits of milk shows evolution in

action.

But intolerance to milk remains common in modern times, say

nutritionists.

In order to digest milk, adult humans need to have a gene which

produces an enzyme called lactase to break down lactose, one of the

main sugars it contains.

Without it, a drink of milk proves an uncomfortable experience,

causing bloating, stomach cramps and diarrhoea.

Today, more than 90% of people of northern European origin have the

gene.

Skeleton study

Working with scientists from Mainz University in Germany, the UCL

team looked for the gene that produces the lactase enzyme in

Neolithic skeletons dating between 5480BC and 5000BC.

The ability to drink milk gave some early Europeans a big survival

advantage

Dr Mark

University College London

These are believed to be from some of the earliest farming

communities in Europe.

The lactase gene was absent from the DNA extracted from these

skeletons, suggesting that these early Europeans would not be

tolerant to milk.

Dr Mark , from UCL, said: " The ability to drink milk is the

most advantageous trait that's evolved in Europeans in the recent

past.

" Although the benefits of milk tolerance are not fully understood,

they probably include the advantage of a continuous supply compared

with the 'boom and bust' of seasonal crops, its nourishing qualities,

and the fact that, unlike stream water, it's uncontaminated with

parasites, making it safer.

" All in all, the ability to drink milk gave some early Europeans a

big survival advantage. "

Milk exposure

The big question for scientists now is how the human population

changed and took advantage of milk consumption.

One theory suggests that small groups who could tolerate lactose

became dominant because they could then farm cattle for milk.

But the UCL team says it is more likely that the genetic mutation

allowing the digestion of milk arose at some point after dairy

farming began.

Dr says the absence of the gene in the remains studied

supports this theory.

If lactose tolerance had come first, the farmers would have already

have had the gene.

As they did not, he suggests the genetic mutation took place at a

later point.

He added: " It's likely that the gene variant arose in one individual

somewhere in northern Europe, and was such an advantage, it spread

quickly.

" This is probably the single most advantageous gene trait in humans

in the last 30,000 years. "

Today's intolerance

Denny, a scientist with the British Nutrition Foundation,

said 'lactase deficiency' affected about 5% of white British people,

and a larger proportion of those from some ethnic minorities.

In some parts of the world, such as Asia and Africa, the vast

majority of people are lactose intolerant to some degree.

Once diagnosed, the usual way to control its symptoms is to restrict

the amount of milk products eaten every day, although nutritionists

say that eliminating dairy products entirely is usually unnecessary.

Denny said: " Lactose intolerance tends to be dose-related and

some people are more sensitive than others, consequently only about a

third of the people with lactase deficiency are actually lactose

intolerant.

" Patients with severe lactose intolerance can usually eat yogurt,

hard cheeses and lactose-reduced milk and all are encouraged to eat

these as a source of calcium and other nutrients. "

Story from BBC NEWS:

http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/6397001.stm

Published: 2007/02/27 00:09:23 GMT