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A study of ancient human bones has revealed how Early Europeans had difficulties digesting milk around 5,000 years after the introduction of farming.

It took at least that long for their genes to evolve until they were no longer intolerant to lactose, the natural sugar in mammalian milk, scientists suggests.

Researchers looked at ancient DNA extracted from 13 individuals buried at archaeological sites in the Great Hungarian Plain - a region known to have been at the crossroads of cultural change in European prehistory.

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A study of ancient human bones has revealed how Early Europeans had a problem drinking milk around 5,000 years after the introduction of farming. Pictured is a Late Bronze Age burial from the site of Ludas-Varjú-dulo, Hungary dated to about 1200 B.C. This individual revealed the onset of lactose tolerance

The samples were taken from the petrus bone, the hardest bone in the human body locating on the skull protecting the inner ear.

According to Professor Ron Pinhasi from the University College Dublin, the high percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold.

'This gave us anywhere between 12 per cent and almost 90 per cent human DNA in our samples compared to somewhere between 0 per cent and 20 per cent obtained from teeth, fingers and rib bones,' he said.

For the first time, these exceptionally high percentage DNA yields from ancient remains made it possible for scientists to systematically analyse a series of skeletons from the same region.

The samples were dated from 5,700 BC to 800 BC, ranging across the Stone, Copper, Bronze and Iron Ages.

'Our findings show progression towards lighter skin pigmentation as hunter and gatherers and non-local farmers intermarried, but surprisingly no presence of increased lactose persistence or tolerance to lactose,' said Professor Ron Pinhasi, from University College Dublin's Earth Institute.

'This means that these ancient Europeans would have had domesticated animals like cows, goats and sheep, but they would not yet have genetically developed a tolerance for drinking large quantities of milk from mammals.'

BRITONS DITCHED FISHY DISHES FOR DAIRY DIETS 6,000 YEARS AGO

Dirty cooking pots have shown that ancient Britons swapped seafood for dairy dishes as they started farming around 6,000 years ago

Dirty cooking pots have shown that ancient Britons swapped seafood for dairy dishes as they started farming around 6,000 years ago.

Scientists have been investigating when and how our ancestors made the transition from hunter gathers to farmers and conducted a large-scale investigation of British archaeological sites dating from around 4,600 BC to 1,400 AD.

To do this, they examined millions of fragments of bone and analysed over 1,000 cooking pots. Professor Richard Evershed of the University of Bristol's School of Chemistry, developed new techniques in an effort to identify fish oils in the pots.

His team showed that more than 99 per cent of the earliest farmer's cooking pots lacked sea food residues, indicating that they were not keen on cooking fish.

The team's findings suggest that early British hunters feasted on venison and wild boar and ate large quantities of sea food, including seals and shellfish.

With the introduction of domestic animals some 6,000 years ago, they quickly gave up wild foods and fishing was largely abandoned as people adopted a new diet based around dairying.

Dr Lucy Cramp, lead author of the study said: 'Amazingly, it was another 4,000 years before sea food remains appeared in pots again, during the Iron Age, and it was only with the arrival of the Vikings that fish became a significant part of our diet.' 

The samples were taken from the petrus bone, the hardest bone in the human body locating on the skull protecting the inner ear

Early Europeans may have practiced dairying to make cheese rather than drink milk

The scientists also found that changes in prehistoric technology, such as the adoption of farming, were linked with a significant influx of new people.

For instance, in the Neolithic or New Stone Age, ancient central Europeans had an appearance closer to Sardinians.

In the Iron Age, there is another shift, with people coming into Central Europe from the East, such as the Caucasus or Asia.

Researchers claim that tolerance to lactose only appeared in the Bronze Age, around 4,000 years after these people began dairying.

Before then, most humans were lactose intolerant, and only later evolved the ability to break down this sugar in animal milk.

The researchers suggest ancient Europeans may have practiced dairying to make cheese and yoghurt, which breaks down lactose, rather than to drink milk.

Scientists are now sequencing ancient genomes dating back 13,000 years to find out about genetic diversity that existed before and after the Ice Age.

Researchers at University College Dublin made the discovery after looked at ancient DNA extracted from 13 individuals buried at archaeological sites in the Great Hungarian Plain