About 10,000 years ago, the prehistoric hunter-gatherers of Europe began meeting some new neighbors.

These farmers spread gradually at first, expanding from the Near East through Anatolia and the Balkans. Then agriculture exploded, reaching present-day Britain within a few thousand years. The farmers settled into houses, which soon evolved into villages, towns and eventually cities.

The archaeological record tells us that much. But what it doesn’t reveal is how agriculture spread. Did it spread like a fad, as hunter-gatherer groups saw what their neighbors were doing and imitated their ways? Or was it more of an invasion, with subsequent generations of farmers advancing across the continent and overwhelming indigenous hunter-gatherer populations as they went?

Some genetic studies suggest the former. But in the September 3 issue of Science, the first study to directly compare ancient DNA (aDNA) from prehistoric burials of hunter-gatherers to that their agricultural neighbors suggests migrants spread farming through Europe.

The research team, led by Barbara Bramanti of Mainz University, sequenced the mitochondrial DNA (mtDNA) of just under 50 individuals unearthed from various prehistoric burial sites across central and eastern Europe. Half the individuals came from hunter-gatherer societies, and the other half from communities based around farming. As a comparison, they also sequenced the mtDNA of nearly 500 modern Europeans from the same parts of Europe.

The authors’ first task was to compare the hunter-gatherer mtDNA to that of the farmers. Upon doing so, they found both groups to be so different from each other that there is no way the two could be closely related. There was absolutely no overlap in the kinds of mtDNA lineages – known as haplogroups – between the hunter-gatherers and the farmers. This stark difference suggests the earliest farmers were not related to the hunter-gatherers, and most likely came to the region by migration.

And how do these two groups compare to the modern-day Europeans? The hunter-gatherers had little in common with modern people. Haplogroup U, the most common lineage among the hunter-gatherers, is one of the least common haplogroups among modern Europeans.

But the authors also found little to connect the farmers to modern Europeans. Other studies have pointed to a substantial genetic component from the Near East among Europeans, but the authors found many genetic differences between the two groups.

Based on these results, the authors have proposed an alternative theory. The unexplained component to the genetic make-up of modern Europeans may be explained by later migrations that post-date the skeletal remains examined here. It could have been a later expansion of farmers from the Near East, or perhaps an influx of hunter-gatherers from the west. The exact details remain unclear, but the authors are confident that, with additional DNA analysis, they can hope to unravel the increasingly complex story of the peopling of Europe.

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On August 20, 79 AD, a series of small tremors and earthquakes began to shake the two ancient Roman cities of Pompeii and Herculaneum.  Lying in the shadow of Mount Vesuvius — about 150 miles south of the Roman capital — the two cities were often hit by tremors and earthquakes, so most residents were unperturbed.  After all, the tremors were relatively mild, especially compared to a severe earthquake that had hit both towns 17 years earlier.

They did not know, however, that this new string of tremors was in fact due to increasing pressure inside Mount Vesuvius; they did not know that Mount Vesuvius was in fact an active volcano; and they did not know that it was about to erupt.

Just four days later, on August 24, Vesuvius did just that.  The cities of Pompeii and Herculaneum were taken completely off guard.  So much so, in fact, that many residents were unable to escape the rain of pumice and ash that fell to dozens of meters high, burying people inside their homes.  Even those who did survive the ash were unable to outrun the pyroclastic flow, a wave of white-hot cinders that tumbled down Mt. Vesuvius at over 100 mph.  In just a few days, these cities became buried, and soon were forgotten.

Pompeii and Herculaneum remained buried for the next 1,600 years, when military engineers digging a new course for the River Samo uncovered what looked to be an underground city.  They had found the remains of the buildings, houses and plazas that made up these two ancient Roman cities.  And – perhaps more importantly – they found the remains of the inhabitants, often almost perfectly preserved.

This was especially true for the remains of 13 individuals, hidden inside a villa belonging to a Pompeii resident named Caius Iulius Polybius.  Inside the villa, two individuals were still holding hands; another was clutching her stomach, the remains of her unborn child still inside. Archaeologists have spent many decades trying to uncover as much as possible about these and the other thousands of individuals found buried in Pompeii and Herculaneum.  Now geneticists have entered the fray, using sophisticated techniques to extract and analyze the DNA of these 13 individuals with the goal of understanding the relationships between them.  The results of this analysis are published in the July issue of the the Annals of Human Genetics.

The research team, led by Giovanni de Bernado from the University of Naples, extracted the mitochondrial DNA (mtDNA) from all 13 individuals.  The mtDNA is passed down, almost always unchanged, from a mother to her children. So researchers can conclude that individuals in a grave or archaeological site who share similar or identical mtDNA profiles – known as haplogroups – are likely related to each other along the maternal line. The mtDNA is also useful in archaeology because it is more likely to remain preserved long after an individual dies.

But there can be problems with preservation when analyzing mtDNA, and that is exactly what happened with a few of the remains.  Di Bernado and his team were unable to extract mtDNA from three of the individuals.  But for the others, they were successful.  In fact, six of the individuals yielded an identical maternal haplogroup assignment:  T2b.  T2b exists in about 4-5% of modern Italians, making it one of the rarer haplogroups in the region.  So for it to exist at such high levels within a single household almost certainly proves some kind of familial relationship between the inhabitants of this house.

Who were the individuals bearing the T2b haplogroup?  Four children ranging in age from three to 14, a young woman of about 18 years, and a man of about 30 years. Di Bernado argues that the four children were probably siblings (or at least cousins), that the 18 year-old woman could perhaps be an older sister or aunt, and the man is likely to be a maternal uncle.  Unfortunately, one of the female remains – who would be an ideal candidate as the childrens’ mother, yielded no reliable mtDNA type.  The remaining individuals bore different haplogroups, and may have represented the father or paternal grandparents.  There is also the possibility that one of the adult women was a mistress of the head of the household, something not uncommon in ancient Rome.

For many years, the identities of the Pompeian and Herculanean victims’ remains, entombed in ash and cinders, have both haunted and intrigued scientists.  Now, with efforts such as the ones performed here by Di Bernado and colleagues, we are learning more about who they were in life, and not just about their final moments.

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Archaeologists rarely agree on anything.  So it’s no surprise that for years two groups of scholars have drawn completely opposite conclusions about the relationship between the ancient people of Thailand and China.

Some experts argue that, thousands of years ago, people from Thailand migrated into East Asia, becoming the ancestors of present-day Chinese peoples.  Others argue the exact opposite: that it was people from East Asia who migrated south into Thailand.  Unfortunately, the sheer complexity of languages and cultures in the region, combined with conflicting archaeological reports, makes it next to impossible to draw concrete conclusions.

In situations like this one researchers increasingly turn to the field of genetics to help fill in the gaps and piece together the history of various populations — and that is just what a team from Thailand has done.  In this month’s issue of the American Journal of Physical Anthropology, a bipartisan team of archaeologists and geneticists from across Thailand describes how the mitochondrial DNA (mtDNA) of both ancient and modern Thai populations can help us understand the peopling of the country.

Because the demographics of Thailand are so complex, the authors felt that just sampling modern Thai populations would not give a clear picture into the peopling of the region.  So, the researchers dug deeper by sampling archaeological remains as well.  They extracted DNA from 43 skeletons excavated at two sites in northeastern Thailand that date to about 3,500 years ago.  The authors chose these particular sites, called Noen U-loke and Ban Lum-Khao, because they represented typical ancient farming communities – some of the earliest settlements in existence.

Right away, the authors noticed the ancient and modern samples were very similar genetically — an indication that within the last 3,500 years, people haven’t moved around very much in northeastern Thailand.  Some of the modern people tested may in fact be descendants of these early Thai farmers – a very exciting prospect.

More importantly, however, the authors believe they have worked out the peopling of Thailand from the genetic information they gathered.  Their data support the hypothesis that many present-day Thai populations are actually descended from people who migrated from southern China only a few thousand years ago – an idea that has gained prominence in recent years among many archaeologists.

These results are compelling for a number of reasons — most notably the fact that the authors were able to use genetic data to resolve uncertainties about the peopling of Thailand when other types of data could not.  It also shows how useful it can be to compare ancient and modern DNA when tracing prehistoric migrations.  Many studies use only one or the other.  Finally, these authors were able to utilize genetics in a region — Southeast Asia — that has not seen much genetics research compared to other regions.  Hopefully future research on the genetic history of this region will continue down the path laid out by these researchers, following their lead of taking evidence from all disciplines in reshaping theories on ancient civilizations.  Perhaps we will even see more agreement from archaeologists.

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About 4,600 years ago, in northern Germany, a small village buried 13 of its residents.  The deceased ranged in age from less than a year to nearly 60 years old and were buried in pairs or small groups. And virtually all of them had suffered violent, probably painful deaths.  Because the majority of the deceased were women or children, the archaeologists who discovered their remains have argued that these victims were likely the unfortunate casualties of a violent raid by a neighboring village — a common occurrence during this period.

Research on the skeletal remains of the deceased, as well as the grave goods with which they were buried, have revealed much about the lifestyle and culture of these early Europeans.  But many questions – especially about the relationships between the buried individuals themselves – were left unanswered.  So, a team of scientists from Germany and the United Kingdom decided to use the DNA preserved in these skeletal remains to discover what relationships – if any – existed between these 13 individuals.  The results of this study are reported in this week’s Proceedings of the National Academy of Sciences.

Specifically, the scientists were interested in whether the individuals buried closest to each other were also close relatives.  The 13 victims were found in four separate graves.  Each contained at least one adult, along with anywhere from one to three children.  As a result, some scientists have speculated that each grave might represent a separate family killed in the attack.   DNA analysis, they argue, would allow them to fill the gaps surrounding the identities of the deceased.

Scientists extracted DNA from the teeth of all 13 individuals.  They focused on the mitochondrial DNA (mtDNA), which is passed down from mother to child, the Y-chromosome, which is passed down from father to son, and small segments of the remaining chromosomes, which are passed down from both parents to their children.  Even though ancient DNA is notoriously difficult to work with, the authors were able to extract usable DNA from nine of the 13 individuals.

The results from one of the four burials, Grave 99, were especially intriguing.  The grave contained the remains of an adult male, an adult female, and two male children.  DNA analysis revealed that the adult female had the same mtDNA type as the two male children (K1b).  Analysis also revealed that the adult male had the same Y-chromosome DNA type as the two male children (R1a).  Due to the ways that mtDNA and Y-chromosome DNA are passed from one generation to the next, these results suggest that the two adults in Grave 99 were husband and wife, and that the two male children were their offspring.  Indeed, the authors had originally hypothesized some sort of connection between these four individuals, because while the two adults adhere to normal burial patterns for the time period (lying toe-to-toe facing south), the two children face north, toward their parents.

The notion of these four individuals being buried together, as a family, raises many questions on the origins of the nuclear family in ancient times.  Even the authors admit that “our image of past family life and structure is still dominated by 19th century ideals, and reconstruction of prehistoric families even now adhere to these orthodox schemes.”  Indeed, there has been little evidence to precisely date the origins of the nuclear family, and this example hardly closes the book on how and when such a social unit developed.  However, it does show that using ancient DNA can be quite useful in determining ancient biological relationships.  Indeed, the results from Grave 99 reveal how important the nuclear family must have been to these villagers; that they chose to bury these four victims not as individuals but as a social unit, huddled together in a single grave.

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The place of Neanderthals in the story of human evolution has been hotly debated for decades.  A distant cousin to our species, Neanderthals had already been in Europe over 250,000 years when Homo sapiens first arrived there 35,000 years ago.

Often called Cro-Magnoids, these first Europeans are believed by many scientists to have out-competed the Neanderthals, gradually driving them to extinction. The alternative theory, that Neanderthals and early humans are more closely related and may have even interbred upon meeting, is less popular, though it hasn’t yet been ruled out.  In order to resolve this debate, scientists have turned to genetics and methods of ancient DNA analysis to help them answer the questions surrounding the relationships between Neanderthals and Cro-Magnoids.

However, the practice of extracting and analyzing ancient DNA remains tricky and fraught with skepticism.  One of the main problems is contamination – anyone who touches fossilized remains runs the risk of contaminating it with his or her own DNA.  So how can we tell if scientists are analyzing the right DNA? A new study in this week’s PLOS One attempts to rectify the contamination problem in a novel way by analyzing the DNA of everyone who touched a fossil for comparison in order to rule out contamination. It will also help us better understand the genetic connection between Cro-Magnoids and Neanderthals.

The Italian team, led by David Caramelli, analyzed DNA from a 28,000-year-old Homo sapiens Cro-Magnoid individual found in Piglacci Cave in Italy.  They also analyzed the DNA of everyone who had touched the remains since its 2003 discovery.  What they found was that the Cro-Magnoid individual was genetically similar to most modern Europeans.  The Cro-Magnoid DNA was also distinct from the researchers’ DNA sequences, showing that none of them had contaminated the sample. When the DNA of the Piglacci Cro-Magnoid individual was compared to previous analyses of Neanderthal DNA, the researchers found that the Cro-Magnoid individual has much more in common genetically with modern European humans than with Neanderthals. These results are important for several reasons.

• First, this is one of the first studies to have obtained a reliable and contaminant-free sample of DNA from a 28,000-year-old Cro-Magnoid.  It will hopefully satisfy the skeptics who had claimed contamination will always be a possibility.
• Second, the genetic similarity of the Cro-Magnoid to modern Europeans, combined with its lack of similarity to Neanderthals, helps solidify the theory that the two ancient groups were not closely related.  Previous studies comparing Neanderthal DNA to modern human DNA have also turned up no genetic similarity.
• Third, the body of evidence now shows that Neanderthals didn’t contribute any DNA to the Cro-Magnoid OR modern human gene pool. Indeed, Caramelli and his colleagues point out that “the burden of proof is now on those who maintain that Neanderthals might have contributed to the modern gene pool.”

Together, the current scientific evidence suggests that instead of merging with Cro-Magnoids Neanderthals must have simply died out, unable to compete with the Cro-Magnoids’ superior technology and greater population size.  The archaeological record shows Neanderthals becoming less and less prevalent around 35,000 years ago, and by 30,000 years ago, they disappear completely.

After their rivals’ disappearance, Cro-Magnoid humans would have to cope with hardships of their own, as the Last Ice Age was approaching its peak.  They would be relegated to the southern fringes of Europe for 5,000 years, awaiting the warming temperatures that would allow them to repopulate the continent.

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