Feeds:
Posts
Comments

Posts Tagged ‘milk’

20130805-113555.jpg

Topic: Milk for the ages

When a single genetic mutation first let ancient Europeans drink milk, it set the stage for a continental upheaval.

In the 1970s, archaeologist Peter Bogucki was excavating a Stone Age site in the fertile plains of central Poland when he came across an assortment of odd artefacts. The people who had lived there around 7,000 years ago were among central Europe’s first farmers, and they had left behind fragments of pottery dotted with tiny holes. It looked as though the coarse red clay had been baked while pierced with pieces of straw.

Looking back through the archaeological literature, Bogucki found other examples of ancient perforated pottery. “They were so unusual — people would almost always include them in publications,” says Bogucki, now at Princeton University in New Jersey. He had seen something similar at a friend’s house that was used for straining cheese, so he speculated that the pottery might be connected with cheese-making. But he had no way to test his idea.

The mystery potsherds sat in storage until 2011, when Mélanie Roffet-Salque pulled them out and analysed fatty residues preserved in the clay. Roffet-Salque, a geochemist at the University of Bristol, UK, found signatures of abundant milk fats — evidence that the early farmers had used the pottery as sieves to separate fatty milk solids from liquid whey. That makes the Polish relics the oldest known evidence of cheese-making in the world.

Roffet-Salque’s sleuthing is part of a wave of discoveries about the history of milk in Europe. Many of them have come from a €3.3-million (US$4.4-million) project that started in 2009 and has involved archaeologists, chemists and geneticists. The findings from this group illuminate the profound ways that dairy products have shaped human settlement on the continent.

During the most recent ice age, milk was essentially a toxin to adults because — unlike children — they could not produce the lactase enzyme required to break down lactose, the main sugar in milk. But as farming started to replace hunting and gathering in the Middle East around 11,000 years ago, cattle herders learned how to reduce lactose in dairy products to tolerable levels by fermenting milk to make cheese or yogurt. Several thousand years later, a genetic mutation spread through Europe that gave people the ability to produce lactase — and drink milk — throughout their lives. That adaptation opened up a rich new source of nutrition that could have sustained communities when harvests failed.

This two-step milk revolution may have been a prime factor in allowing bands of farmers and herders from the south to sweep through Europe and displace the hunter-gatherer cultures that had lived there for millennia. “They spread really rapidly into northern Europe from an archaeological point of view,” says Mark Thomas, a population geneticist at University College London. That wave of emigration left an enduring imprint on Europe, where, unlike in many regions of the world, most people can now tolerate milk. “It could be that a large proportion of Europeans are descended from the first lactase-persistent dairy farmers in Europe,” says Thomas.

Strong stomachs

Young children almost universally produce lactase and can digest the lactose in their mother’s milk. But as they mature, most switch off the lactase gene. Only 35% of the human population can digest lactose beyond the age of about seven or eight (ref. 2). “If you’re lactose intolerant and you drink half a pint of milk, you’re going to be really ill. Explosive diarrhoea — dysentery essentially,” says Oliver Craig, an archaeologist at the University of York, UK. “I’m not saying it’s lethal, but it’s quite unpleasant.”

Most people who retain the ability to digest milk can trace their ancestry to Europe, where the trait seems to be linked to a single nucleotide in which the DNA base cytosine changed to thymine in a genomic region not far from the lactase gene. There are other pockets of lactase persistence in West Africa (see Nature 444, 994–996; 2006), the Middle East and south Asia that seem to be linked to separate mutations (see ‘Lactase hotspots’).

The single-nucleotide switch in Europe happened relatively recently. Thomas and his colleagues estimated the timing by looking at genetic variations in modern populations and running computer simulations of how the related genetic mutation might have spread through ancient populations. They proposed that the trait of lactase persistence, dubbed the LP allele, emerged about 7,500 years ago in the broad, fertile plains of Hungary.

Powerful gene

Once the LP allele appeared, it offered a major selective advantage. In a 2004 study, researchers estimated that people with the mutation would have produced up to 19% more fertile offspring than those who lacked it. The researchers called that degree of selection “among the strongest yet seen for any gene in the genome”.

Compounded over several hundred generations, that advantage could help a population to take over a continent. But only if “the population has a supply of fresh milk and is dairying”, says Thomas. “It’s gene–culture co-evolution. They feed off of each other.”

To investigate the history of that interaction, Thomas teamed up with Joachim Burger, a palaeogeneticist at the Johannes Gutenberg University of Mainz in Germany, and Matthew Collins, a bioarchaeologist at the University of York. They organized a multidisciplinary project called LeCHE (Lactase Persistence in the early Cultural History of Europe), which brought together a dozen early-career researchers from around Europe.

By studying human molecular biology and the archaeology and chemistry of ancient pottery, LeCHE participants also hoped to address a key issue about the origins of modern Europeans. “It’s been an enduring question in archaeology — whether we’re descended from Middle Eastern farmers or indigenous hunter-gatherers,” says Thomas. The argument boils down to evolution versus replacement. Did native populations of hunter-gatherers in Europe take up farming and herding? Or was there an influx of agricultural colonists who outcompeted the locals, thanks to a combination of genes and technology?

One strand of evidence came from studies of animal bones found at archaeological sites. If cattle are raised primarily for dairying, calves are generally slaughtered before their first birthday so that their mothers can be milked. But cattle raised mainly for meat are killed later, when they have reached their full size. (The pattern, if not the ages, is similar for sheep and goats, which were part of the dairying revolution.)

On the basis of studies of growth patterns in bones, LeCHE participant Jean-Denis Vigne, an archaeozoologist at the French National Museum of Natural History in Paris, suggests that dairying in the Middle East may go all the way back to when humans first started domesticating animals there, about 10,500 years ago. That would place it just after the Middle Eastern Neolithic transition — when an economy based on hunter-gathering gave way to one devoted to agriculture. Dairying, says Roz Gillis, also an archaeozoologist at the Paris museum, “may have been one of the reasons why human populations began trapping and keeping ruminants such as cattle, sheep and goats”. (See ‘Dairy diaspora’.)

Dairying then expanded in concert with the Neolithic transition, says Gillis, who has looked at bone growth at 150 sites in Europe and Anatolia (modern Turkey). As agriculture spread from Anatolia to northern Europe over roughly two millennia, dairying followed a similar pattern.

On their own, the growth patterns do not say whether the Neolithic transition in Europe happened through evolution or replacement, but cattle bones offer important clues. In a precursor study, Burger and several other LeCHE participants found that domesticated cattle at Neolithic sites in Europe were most closely related to cows from the Middle East, rather than indigenous wild aurochs. This is a strong indication that incoming herders brought their cattle with them, rather than domesticating locally, says Burger. A similar story is emerging from studies of ancient human DNA recovered at a few sites in central Europe, which suggest that Neolithic farmers were not descended from the hunter-gatherers who lived there before.

Taken together, the data help to resolve the origins of the first European farmers. “For a long time, the mainstream of continental European archaeology said Mesolithic hunter-gatherers developed into Neolithic farmers,” says Burger. “We basically showed they were completely different.”

Milk or meat

Given that dairying in the Middle East started thousands of years before the LP allele emerged in Europe, ancient herders must have found ways to reduce lactose concentrations in milk. It seems likely that they did so by making cheese or yogurt. (Fermented cheeses such as feta and cheddar have a small fraction of the lactose found in fresh milk; aged hard cheeses similar to Parmesan have hardly any.)

To test that theory, LeCHE researchers ran chemical tests on ancient pottery. The coarse, porous clay contains enough residues for chemists to distinguish what type of fat was absorbed during the cooking process: whether it was from meat or milk, and from ruminants such as cows, sheep and goats or from other animals. “That gave us a way into saying what types of things were being cooked,” says Richard Evershed, a chemist at the University of Bristol.

Evershed and his LeCHE collaborators found milk fat on pottery in the Middle Eastern Fertile Crescent going back at least 8,500 years, and Roffet-Salque’s work on the Polish pottery offers clear evidence that herders in Europe were producing cheese to supplement their diets between 6,800 and 7,400 years ago. By then, dairy had become a component of the Neolithic diet, but it was not yet a dominant part of the economy.

That next step happened slowly, and it seems to have required the spread of lactase persistence. The LP allele did not become common in the population until some time after it first emerged: Burger has looked for the mutation in samples of ancient human DNA and has found it only as far back as 6,500 years ago in northern Germany.

Models created by LeCHE participant Pascale Gerbault, a population geneticist at University College London, explain how the trait might have spread. As Middle Eastern Neolithic cultures moved into Europe, their farming and herding technologies helped them to out-compete the local hunter-gatherers. And as the southerners pushed north, says Gerbault, the LP allele ‘surfed’ the wave of migration.

Lactase persistence had a harder time becoming established in parts of southern Europe, because Neolithic farmers had settled there before the mutation appeared. But as the agricultural society expanded northwards and westwards into new territory, the advantage provided by lactase persistence had a big impact. “As the population grows quickly at the edge of the wave, the allele can increase in frequency,” says Gerbault.

The remnants of that pattern are still visible today. In southern Europe, lactase persistence is relatively rare — less than 40% in Greece and Turkey. In Britain and Scandinavia, by contrast, more than 90% of adults can digest milk.

Cattle conquest

By the late Neolithic and early Bronze Age, around 5,000 years ago, the LP allele was prevalent across most of northern and central Europe, and cattle herding had become a dominant part of the culture. “They discover this way of life, and once they can really get the nutritional benefits they increase or intensify herding as well,” says Burger. Cattle bones represent more than two-thirds of the animal bones in many late Neolithic and early Bronze Age archaeological sites in central and northern Europe.

The LeCHE researchers are still puzzling out exactly why the ability to consume milk offered such an advantage in these regions. Thomas suggests that, as people moved north, milk would have been a hedge against famine. Dairy products — which could be stored for longer in colder climes — provided rich sources of calories that were independent of growing seasons or bad harvests.

Others think that milk may have helped, particularly in the north, because of its relatively high concentration of vitamin D, a nutrient that can help to ward off diseases such as rickets. Humans synthesize vitamin D naturally only when exposed to the sun, which makes it difficult for northerners to make enough during winter months. But lactase persistence also took root in sunny Spain, casting vitamin D’s role into doubt.

The LeCHE project may offer a model for how archaeological questions can be answered using a variety of disciplines and tools. “They have got a lot of different tentacles — archaeology, palaeoanthropology, ancient DNA and modern DNA, chemical analysis — all focused on one single question,” says Ian Barnes, a palaeogeneticist at Royal Holloway, University of London, who is not involved in the project. “There are lots of other dietary changes which could be studied in this way.”

The approach could, for example, help to tease apart the origins of amylase, an enzyme that helps to break down starch. Researchers have suggested that the development of the enzyme may have followed — or made possible — the increasing appetite for grain that accompanied the growth of agriculture. Scientists also want to trace the evolution of alcohol dehydrogenase, which is crucial to the breakdown of alcohol and could reveal the origins of humanity’s thirst for drink.

Some of the LeCHE participants are now probing further back in time, as part of a project named BEAN (Bridging the European and Anatolian Neolithic), which is looking at how the first farmers and herders made their way into Europe. Burger, Thomas and their BEAN collaborators will be in Turkey this summer, tracing the origins of the Neolithic using computer models and ancient-DNA analysis in the hope of better understanding who the early farmers were, and when they arrived in Europe.

Along the way, they will encounter beyaz peynir, a salty sheep’s-milk cheese eaten with nearly every Turkish breakfast. It is probably much like the cheese that Neolithic farmers in the region would have eaten some 8,000 years ago — long before the march of lactase persistence allowed people to drink fresh milk.

Original article:
nature.com
By Andrew Curry July 16, 2013

20130805-113609.jpg

Read Full Post »

Topic: Cheese

Milk products may be why the hunter-gatherer lifestyle was given up in favor of a more settled, and yogurt-eating, existence.

THE GIST

People were processing dairy products in the African Sahara more than 7,000 years ago.

The first dairy farmers lived in Anatolia, now modern-day Turkey.

Dairy farming may have pushed people to settle down.

More than 7,000 years ago, prehistoric people in the African Sahara were making dairy products, such as butter, yogurt and cheese.

The discovery, based on the identification of dairy fats on ancient pottery shards found in Libya, is the first to provide a definitive date for early dairy farming in Africa. Adding to findings from Europe and the Middle East, the study points to milk products as a main reason why people in many places may have chosen to give up the hunter-gatherer lifestyle in favor of a more settled existence.

“What we’re really beginning to know is that cattle were incredibly significant to early peoples,” said Julie Dunne, an archaeological scientist at the University of Bristol in the United Kingdom. “They gave a remarkably calorific source of food and allowed populations to expand dramatically. Milk and dairying seem to be so significant in human development, remarkably so.”

Plenty of research has documented the domestication of sheep, goats and cattle, as well as the use of dairy products, beginning around 9,000 years ago in parts of modern-day Turkey, 8,000 years ago in eastern Europe and 6,000 years ago in Britain.

In Africa, details have been murkier. Fossil evidence suggests the arrival of domesticated milk-producers in North Africa by about 8,000 years ago with an increase in animal numbers over the next 1,000 years, but remains are spotty. And even though archaeologists have discovered vivid rock art depicting cattle and even milking scenes in Algeria and other parts of the Sahara, it is impossible to accurately date those paintings.

For the new study, Dunne and colleagues analyzed organic residues on 81 well-dated pieces of pottery taken from the Takarkori rock shelter in the Libyan Sahara. The samples turned out to be incredibly well preserved, containing fat residues at high concentrations, probably because of the region’s dry conditions — though the climate there was much wetter during the period considered in the new study.

Evidence showed that some pots were used to hold plant oils. But many contained chemical signatures that were unambiguously from animal fats, the researchers report today in the journal Nature. Analyses revealed the remains of dairy products made from cow, goat and sheep’s milk, dating back to between 7,200 and 5,800 years ago.

At that time, Africans had not yet developed the genetic mutations that allow people to digest milk, according to other research. So, the Sahara’s lactose-intolerant dairy farmers were likely making yogurt and cheese rather than drinking straight from the udders of their animals. Only after people learned to process dairy foods did their bodies develop the ability to drink pure milk — through mutations that appear to have happened independently as many as three or four times in Africa.

It is now becoming clear that dairying was a transformative development in human history, said Joachim Burger, an evolutionary anthropologist at the University of Mainz in Germany. Given their carbohydrate and nutrient profiles, dairy products would have been far superior to what people could get from hunting and gathering alone. And when our ancestors figured that out, society changed forever.

“The general question behind all this is what actually made man to become sedentary and change his lifestyle completely,” Burger said. “Milk is not just a side effect of this change. It may even be a driving force behind it.”

Original article:

DiscoveryNews

By Emily Sohn Wed Jun 20, 2012

Read Full Post »

Topic-Milk is the ticket!

Glass of Milk

The Romans, as Monty Python famously acknowledged, have done many things for us. Contrary to popular wisdom, however, improving our diet was not one of them.

A study of the remains of almost 20,000 people dating from the 8th century BC to the 18th century AD has found that the Roman empire reduced our level of nutrition, which increased again in the “dark ages”.

That is because the key factor in determining average height over the centuries – an indicator of nutritional status and wellbeing – has been an increase in milk consumption due to improved farming. Higher population densities and the need to feed the army during Roman times may have worked against this.

The “anthropometric” approach pursued by Nikola Koepke of Oxford University, which combines biology and archaeology, suggests longer bone length is indicative of improved diet. Koepke’s study, presented at the Economic History Society’s 2010 annual conference, also challenges assumptions about the effect of the industrial revolution. Urbanisation did not improve wellbeing, she argues, at least as measured by height.

Rather, Koepke says, the key factor in determining average height growth over the past 2,500 years has been the increased consumption of milk as a result of the spread of, and improvements in, farming. She found that overall European living conditions improved slightly in the past 2,500 years even in the centuries prior to the industrial revolution.

Her study is based on data compiled from analysing the skeletal remains of more than 18,500 individuals of both genders from all social classes, from 484 European archaeological dig sites. “Higher milk consumption as indicated by cattle share had a positive impact on mean height,” Koepke writes. “Correspondingly, this determinant is the key factor in causing significant European regional differences in mean height.”

Original article

By Jamie Doward

04/04/2010

guardian.co.uk

Read Full Post »

Topic: Milk

The hunter-gatherers who inhabited the southern coast of Scandinavia 4,000 years ago were lactose intolerant. This has been shown by a new study carried out by researchers at Uppsala University and Stockholm University. The study, which has been published in the journal BMC Evolutionary Biology, supports the researchers’ earlier conclusion that today’s Scandinavians are not descended from the Stone Age people in question but from a group that arrived later.

“This group of hunter-gatherers differed significantly from modern Swedes in terms of the DNA sequence that we generally associate with a capacity to digest lactose into adulthood,” says Anna Linderholm, formerly of the Archaeological Research Laboratory, Stockholm University, presently at University College Cork, Ireland.

According to the researchers, two possible explanations exist for the DNA differences.

“One possibility is that these differences are evidence of a powerful selection process, through which the Stone Age hunter-gatherers’ genes were lost due to some significant advantage associated with the capacity to digest milk,” says Anna Linderholm. “The other possibility is that we simply are not descended from this group of Stone Age people.”

The capacity to consume unprocessed milk into adulthood is regarded as having been of great significance for human prehistory.

“This capacity is closely associated with the transition from hunter-gatherer to agricultural societies,” says Anders Götherström of the Department of Evolutionary Biology at Uppsala University.

He serves as coordinator of LeCHE (Lactase persistence and the early Cultural History of Europe), an EU-funded research project focusing on the significance of milk for European prehistory.

“In the present case, we are inclined to believe that the findings are indicative of what we call “gene flow,” in other words, migration to the region at some later time of some new group of people, with whom we are genetically similar,” he says. “This accords with the results of previous studies.”

The researchers’ current work involves investigating the genetic makeup of the earliest agriculturalists in Scandinavia, with an eye to potential answers to questions about our ancestors.

Original article:

 Anders Götherström
04/01/2010

Eurekalert.org

Read Full Post »

Topic Got Milk?

 An international team of archaeologists has uncovered the earliest known evidence of horses being domesticated by humans. The discovery suggests that horses were both ridden and milked. The findings could point to the very beginnings of horse domestication and the origins of the horse breeds we know today. Led by the Universities of Exeter and Bristol (UK), the research is published on Friday 6 March 2009 in journal Science.

The researchers have traced the origins of horse domestication back to the Botai Culture of Kazakhstan circa 5,500 years ago. This is about 1,000 years earlier than thought and about 2,000 years earlier than domestic horses are known to have been in Europe. Their findings strongly suggest that horses were originally domesticated, not just for riding, but also to provide food, including milk.

Through extensive archaeological fieldwork and subsequent analysis, using new techniques, the team developed three independent lines of evidence for early horse domestication. Their findings show that in the fourth millennium BC horses in Kazakhstan were being selectively bred for domestic use. They also show horses were being harnessed, possibly for riding, and that people were consuming horse milk.

Analysis of ancient bone remains showed that the horses were similar in shape to Bronze Age domestic horses and different from wild horses from the same region. This suggests that people were selecting wild horses for their physical attributes, which were then exaggerated through breeding.

The team used a new technique to search for ‘bit damage’ caused by horses being harnessed or bridled. The results showed that horses had indeed been harnessed, suggesting they could have been ridden.

Using a novel method of lipid residue analysis, the researchers also analysed Botai pottery and found traces of fats from horse milk. Mare’s milk is still drunk in Kazakhstan, a country in which horse traditions run deep, and is usually fermented into a slightly alcoholic drink called ‘koumiss’. While it was known that koumiss had been produced for centuries, this study shows the practice dates back to the very earliest horse herders.

Lead author Dr Alan Outram of the University of Exeter said: “The domestication of horses is known to have had immense social and economic significance, advancing communications, transport, food production and warfare. Our findings indicate that horses were being domesticated about 1,000 years earlier than previously thought. This is significant because it changes our understanding of how these early societies developed.”

The steppe zones, east of the Ural Mountains in Northern Kazakhstan, are known to have been a prime habitat for wild horses thousands of years ago. They were a commonly hunted animal. This may have set the stage for horse domestication by providing indigenous cultures with access to plentiful wild herds and the opportunity to gain an intimate knowledge of equine behaviour. Horses appear to have been domesticated in preference to adopting a herding economy based upon domestic cattle, sheep and goats. Horses have the advantage of being adapted to severe winters and they are able to graze year round, even through snow. Cattle, sheep and goats need to be to be provided with winter fodder, and were a later addition to the prehistoric economies of the region.

This study was carried out by the Universities of Exeter, Bristol and Winchester (UK), Carnegie Museum of Natural History (Pittsburgh, USA), and Kokshetau University (Kazakhstan) and was supported by the Natural Environment Research Council, British Academy and National Science Foundation of America.

Original Article:

Science Daily

March 8, 2009

Adapted from materials provided by University of Exeter.

Read Full Post »

Topic: Milk

My Thoughts:

Got Milk?  This article from LONDON, Sept. 2 (UPI) links milk to genetics!  It could explain much of the emphasis we, ( America and  much of Europe) on the necessity for three glasses of milk a day. In many cultures around the world people stop drinking milk  as small children. 

 

British researchers have determined the ability to digest the milk sugar lactose evolved in central European dairy farming communities about 7,500 years ago.

University College London scientists said the genetic change that enabled early Europeans to drink milk without becoming sick has been mapped to dairying farmers who lived in a region between the central Balkans and central Europe.

In the new study, the researchers said they used a computer simulation model that integrated genetic and archaeological data using newly developed statistical approaches.

Traces of fats point to dairying at the onset of farming in England some 6,100 years ago, said Professor Mark Thomas, who led the study. But he said it’s most likely milk was first fermented to make yogurt, butter and cheese, and not drunk fresh.

“Our study simulated the spread of lactase persistence and farming in Europe, and found that lactase persistence appears to have begun around 7,500 years ago … probably among people of the Linearbandkeramik culture,” said Thomas.

Thomas said the spread of fresh milk drinking from the Balkans across Europe explains why most European lactase-persistent people carry the same version of the gene that causes it.

The study appears in the journal PLoS Computational Biology.

Read Full Post »

« Newer Posts

%d bloggers like this: