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vulkan02
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Topic: "Early" Europeans unable to disgest milk Posted: 28-Feb-2007 at 20:09 |
Early Europeans unable to stomach milk
Researchers must saw the bone to access the DNA inside it (Image: AG Palaeogenetik)
The study included bones from eight Neolithic Europeans (Image: Joachim Burger)
Researchers
analysing the DNA in Neolithic human remains claim to have uncovered
the first direct evidence that modern humans have evolved changes in
response to natural selection.
Just
7000 years ago, Europeans were unable to digest milk, according to a
new analysis of fossilised bone samples nowadays more than 90% of
this population can.
Europeans
must have incurred a rapid change in their genetic make-up because it
held an evolutionary advantage for them to be able to digest milk, says
Mark Thomas at University College London in the UK, who carried out the
study with colleagues.
However, other experts caution that larger studies are needed to support the conclusions of this research.
Milking it
The
majority of humans around the world lose the ability to digest lactose
a sugar in milk before reaching adulthood. This is because their
gene for the enzyme lactase, which breaks lactose down, is switched off
by late adolescence. Symptoms of this lactose intolerance include
bloating and diarrhoea after drinking milk.
However,
over 90% of northern Europeans have a version of the lactase gene that
remains active throughout life, enabling them to continue drinking milk
as adults.
To
determine when this special lactose tolerance evolved in Europe,
Thomass team analysed the DNA from 55 bone samples belonging to eight
Neolithic Europeans. The skeletons were dated to between 5840 BC and
5000 BC.
Constant supply
After
extracting the DNA from the fossils, researchers identified the
sequence of the lactase gene for each of the eight Neolithic
individuals. Surprisingly, says Thomas, none of the early Europeans had
the gene mutation associated with lactose tolerance in modern-day
Europeans.
Based
on this result, he believes that the mutation for lactose tolerance
spontaneously arose in Europe within the past 7000 years and quickly
became prevalent through natural selection.
He
explains that the ability to digest milk would give a massive survival
advantage to people living thousands of years ago: milk from cows is
uncontaminated by parasites, making it safer to drink than stream
water. It is also available all year long, unlike seasonal crops.
Thomas
also notes that the low levels of sunlight in northern Europe during
winter mean that people have lowered levels of vitamin D in their
bodies, and therefore have difficulty absorbing calcium. Milk solves
this problem by providing them with both calcium and some vitamin D.
Prone to error
Thomas
says the comparison of the fossil DNA and present-day European genes
provides a before-and-after snapshot that provides the first ever
direct evidence that humans have changed in response to natural
selection.
This
is a fascinating and important study, says bio-archaeologist Clark
Larsen of Ohio State University in Columbus, Ohio, US. It offers a new
window onto past human genetic variation, and is truly an important
development in the history of our science and in the study of the past.
But
Larsen adds that larger studies of fossils are needed to confirm the
absence of the lactose tolerance gene in Neolithic Europeans. He and
others stress that the process of extracting and analysing DNA from
fossils is very complicated and prone to error.
The
ability to decipher genes from fossils is a great feat in and of
itself, says Ripan Malhi at the University of Illinois
Urbana-Champaign, US. And Malhi says he believes that other examples of
direct evidence for relatively recent natural selection acting on
humans may be out there.
Journal reference: Proceedings of the National Academy
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Adalwolf
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Posted: 28-Feb-2007 at 22:13 |
Nice article! I love milk! I drink 2 cups a day, whole milk if I can get it, but sadly, they don't have it at the cafeteria!
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vulkan02
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Posted: 28-Feb-2007 at 22:43 |
Are you sure you can digest it though?
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Adalwolf
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Posted: 28-Feb-2007 at 23:12 |
Originally posted by vulkan02
Are you sure you can digest it though?
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Aye! I'm decsended from northern Europeans, have drank milk all my life, and have never been sick from it!
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pekau
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Posted: 01-Mar-2007 at 16:08 |
Wow, that must be sad. And at that time, they didn't even had any soft drinks. So the only thing that people can drink are water, wine and alcoholic drinks... but just water for commoners. How sad, just drinking water everyday...
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tommy
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Posted: 05-Mar-2007 at 12:37 |
Even today, it is more difficult for many Han Chinese to digest milk.
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leung
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tommy
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Posted: 05-Mar-2007 at 12:39 |
what kind of milk the early european could not digest,from cow, horse, or goat. a
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leung
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vulkan02
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Posted: 05-Mar-2007 at 18:37 |
All kinds I believe it doesn't matter, but as the article points out they lose the ability to disgest lactose later in life.
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Kashmiri
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Posted: 07-Mar-2007 at 18:23 |
lol us indians have been drinking milk for thousands of years without any problems. we drink milk directly from cows
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malizai_
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Posted: 07-Mar-2007 at 21:47 |
welcome to AE kashmiri
What do you mean by "we drink milk directly from cows ".
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Adalwolf
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Posted: 08-Mar-2007 at 02:51 |
Maybe it isn't pastuerized?
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Constantine XI
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Posted: 08-Mar-2007 at 06:13 |
It is unsurprising so far as I am concerned. Just look at the ability
of milk digestion in peoples who have traditionally never had a strong
tradition in keeping livestock. A great many Africans lack the ability
to digest milk.
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Kashmiri
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Posted: 08-Mar-2007 at 11:07 |
preety much directly from cows
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Knights
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Posted: 13-Mar-2007 at 05:51 |
As in...directly??...OK then. Has anyone tried camel's milk ice cream?
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Xshayathiya
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Posted: 13-Mar-2007 at 11:39 |
Originally posted by tommy
Even today, it is more difficult for many Han Chinese to digest milk. |
From what I understand 90% of Chinese are lactose intolerant
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Cywr
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Posted: 03-Apr-2007 at 15:57 |
Originally posted by malizai_
welcome to AE kashmiri
What do you mean by "we drink milk directly from cows ". |
Kinky peeps them Indians, they wrote the kama sutra and like to do it cow style ;) I assume the implication is that is consumed fresh, farmhouse style. Though he brings up an overlooked point, there are probably more lactose tolerant people in the Indian sub-continent area than there are in Europe. Likewise there a few cattle dependant tribes in Africa that display high rates of lactose tolerance. So its a chicken and egg thing, did cattle grazing select lactose tolerance, or did lactose tolerance make cattle grazing viable and give them an edge over the old nuts and berries folk? IIRC there are two main theories, the one that it evolved seperatly due to local pressures in different populations, and the other that it originated possibly in the Middle East and spread outwards from there possibly with the spred of certain forms of agriculture. That it should be highest in Sweden could thus be that A it was settled by populations who already had a lifestyle based on herding (cattle, and reindeer for the Sami) and B that the more extreme climate made dependance on milk more important. The question i have is, are Llama's any good for miulk production? And how do Andean people fair to other American populatons in th elactose tolerance department? Could it be simply that cows milk (which is easiest for humans to digest AFAIK) made it easier for populations that had access to domesticated cows to embrace the lifestyle (and this gradualy select people with the tolerance trait)? This would would allow for multiple regional lactose tolerance development, on the othe rhand it could be a lifestyle spreading slowly outwards from the middle east or whatever. Maybe it was a mix of both theories. Interestingly, i've heard (but not entirely sure), that european domestic cat breeds are morely likely to be lactose tolerant, perhaps a shared lifestyle, or accepting a particular pattern of domestication made them more favourable to humans?
Edited by Cywr - 03-Apr-2007 at 16:00
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Posted: 14-Jun-2007 at 23:36 |
I would question the semantics here. To say the Neanderthals didn't drink milk could be true, I haven't met any lately to ask them, but to say early Europeans (as known today) didn't drink milk would be nonsense. They also drank mare's milk and ate horse meat but didn't ride horses until much later.
I have heard of modern Asians and Africans being lactose intolerant, for the dairy cow is not a tropical animal and not native to the equatorial belt. They need cooler weather to survive. Now days, in the Philippines for instance, what is called the "Phillipino steers" have been successfully introduced into cooler mountainous areas. The Asian buffalo is a different species, but must check that out.
Edited by elenos - 14-Jun-2007 at 23:50
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elenos
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Maharbbal
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Posted: 15-Jun-2007 at 12:46 |
you don't seem to uderstand that they lack the ability to diggest milk in great quantities because they are intolerant to lactose (ie do not produce lactase) they are incapable to drink any form of dairy be it human, cow, goat, camel whatever. It may be possible that some animal have a lower rate of lactose in their milk but it is merely an hypothesis.
Besides, some European population are still highly lactose intolerant (Ashkenazi, Italians). There is no doubt that the practice of drinking milk arose progressively but evidence are that in Europe too it took time (variation between countries indicate it).
I'm interested by any evidence of the contrary though.
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Cywr
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Posted: 16-Jun-2007 at 10:09 |
It may be possible that some animal have a lower rate of lactose in their milk but it is merely an hypothesis. |
Its more than a mere hypothesis. The fact is that everything from lactose levels, to fat content to energy varies quite a bit from breed to breed, and from species to species. IIRC Goats milk tends to have lower lactose levels than cows milk, which in turn has lower lactose levels than Horse milk. Buffalo milk is slightly lactose richer than cows milk IIRC. Seeing as you mentioned Italy, its actualy rather interesting. The tendancy is to assume a north south difference, which is true, in the North lactose tolerance is much more common than the south, but by region, Central Italy has the highest rates of tolerance, with rates comparable with Northern Europe. Geographic distribution of the triat is rather flunky. @elenos Cattle is important in parts of Sahel belt, indeed it is here that you find Arficans with the highest levels of Lactose tolerance AFAIK.
Edited by Cywr - 16-Jun-2007 at 10:18
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elenos
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Posted: 23-Jun-2007 at 02:39 |
Hi Cwyr, I assume the Asians don't drink buffalo milk?I really have no idea even though I have been to Asia. Then the Sahara is sub-tropical? That makes the difference from the tropical. Even in the sub-tropics they have trouble with the tsetse fly on cattle and other nasty bitey things that obviously evolved in tropical areas but spread to find a survival niche in other areas.
The trouble with studying Africa is the climate belts don't travel in straight lines like on the map and so the migration and settlement routes of different peoples becomes blurred. Would you say, like in this question of lactose intolerance, people tend to keep some internal traits of the areas their ancestors evolved in?
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elenos
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