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Human Genome

Scientists Sequence 5,700-Year-Old Human Genome

Despite rapid scientific advancements over the past several years, little is known about the lives of prehistoric humans, who left behind no written records and few artifacts. However, scientists were recently able to sequence a prehistoric human genome from DNA left in birch pitch, discovered in Denmark, which was used as chewing gum 5,700 years ago and was preserved in mud. This rare insight into our species’ genetic history gives scientists new information about our distant past, particularly with respect to how human beings have changed genetically over the past few millennia due to evolution. The discovery represents a breakthrough in our understanding of prehistoric human life, as the research presents insights into the diet, lifestyle, and genetic makeup of our distant ancestors.

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The results of the research were published by Nature in a paper that provides extensive detail about the methodology used to analyze the birch pitch as well as the implications of this analysis on our understanding of human history. By looking both at the complete human DNA which was found in the pitch as well as DNA from other plants and animals that the prehistoric individual may have eaten, the researchers determined information about the nearly six thousand year old person and extrapolated from this data to speculate about the larger culture she was a part of. 

The human DNA revealed that the person, whom scientists named “Lola,” was female and probably had dark skin, dark brown hair, and blue eyes. Given that the birch pitch was found in Europe, the fact that Lola had dark skin is notable, as it suggests that the spread of the trait of light skin pigmentation did not occur until later in history. Additionally, the DNA showed that Lola was lactose-intolerant, supporting the theory that tolerance to lactose evolved later in the history of human evolution after the beginning of dairy farming.

Lola, and by extension people who lived in Denmark at the time, likely lived a hunter-gatherer lifestyle, suggesting that this lifestyle persisted for longer in prehistory than scientists had previously assumed. In addition to providing a complete picture of Lola’s genome, the tree birch sample also gave scientists a snapshot of her “oral microbiome signature,” or the various species of bacteria that lived in her mouth at the time. 

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One of the species of bacteria they discovered was Streptococcus pneumoniae, suggesting Lola may have been suffering from a respiratory infection at the time. They also found evidence that Lola may have had mononucleosis, commonly known today as “mono.” Additionally, the scientists found DNA from animals and plants that were likely part of Lola’s diet, including hazelnut and mallard, supporting the opinion that Lola and the people living around her primarily found their food by hunting and gathering. While the evidence provides a genetic snapshot of a moment in Lola’s life, other details of her story, including her age and the cause of her death, will likely never be known.

 

Bronze Age

New Study Reveals Lifestyle of Bronze Age Humans

Given the extent to which all of our lives have been shaped by the rapid pace of technological advancement, it can be hard to imagine how early humans, during an era when the most complicated technological devices in existence were iron tools, went about their day-to-day lives. But a study published today in Science Magazine presents new findings about the social behaviors of people living during the Bronze Age in Europe, and the conclusions reveal surprising differences and similarities with how humans live today. The research, which focused on groups of families living roughly 5,000 years ago, illustrates the details of marital practices, patterns of inheritance, and the emergence of social inequality within small homestead communities.

The report, entitled “Kinship-based social inequality in Bronze Age Europe,” expands on prior research establishing the presence of social inequality based on palace-like structures and elaborate burials for high-status individuals by looking at inequalities on a smaller scale, within individual households. The researchers found a hierarchy within houses, in which a wealthy and high-status family shared living space with unrelated members, who may have been servants or slaves. These conclusions were based on examinations of skeletal remains, as higher-class individuals, who were buried near their places of residence, were found with weapons and ornate jewelry, whereas lower-class people were not. The fact that these individuals were buried in the same graveyard suggests the presence of social inequality, and perhaps slavery, on a smaller scale and roughly 1,500 years before slavery was first known to exist in ancient Greece and Rome.

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The absence of written records from this era makes it difficult for anthropologists to ascertain details about family and household arrangements from the era. As such, the researchers adopted a multidisciplinary approach, taking advantage of genetics, isotopic data, and archaeological techniques. By focusing in detail on a relatively small prehistoric community, the scientists reconstructed numerous family trees spanning four or five generations, and determined the socioeconomic status and geographic origin of individual family members. 

The researchers found that in nearly all of the homes, the females were not related to the males, and only male lineages were identified. This is the result of a Bronze Age marital practice called “patrilocality,” in which newlywed wives moved in with their husband’s family, and daughters left the household. The network of marriages this practice led to, according to the researchers, “likely strengthened and upheld contacts across large distances” and enabled cultural and genetic exchange.

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Though the researchers were able to discern the marriage patterns of these early humans, other elements of their social structures remain unknown. For instance, the researchers don’t know whether women were free to choose their partners or if their partners were chosen by their families, or if women were captured and brought into the communities. They did find, however, that high socioeconomic status was passed down from generation to generation, and while the findings were limited to a small region in Europe, archeological evidence suggests that the social system applied to a broader region as well.

While the study’s results are arguably groundbreaking, they were met with criticism from the scientific community. Some scientists took issue with the researchers’ method of inferring social status by observing whether people were buried next to valuable goods, suggesting that the presence of these items could be related to reasons other than the buried person’s social status. Additionally, one scientist questioned the assumption that low-status individuals were slaves, arguing that the social dynamics were likely more complex than a master-slave relationship. Nevertheless, this new research is likely to inspire further research on the subject, and uncover more details about the lives of prehistoric humans.