Monday, November 2, 2015

Asians and Europeans; Lactose-Intolerant 5,000 Years Ago

     Studying ancient DNA has always been a big part of genetics as it gives insight into the past history of humans. What was generally already found is that around 5,000 years ago, Europeans and Asians are generally light-skinned and - surprisingly - lactose intolerant. During the Bronze Age, which ranged from the years of 3,000 - 5,000 years ago, was a time of mass human migrations throughout the region of Europe and Asia. Because of these large migrations, the present-day demographic structure has been developed. 
     Researchers have sequenced genomes from 101 unearthed ancient humans from Europe and Asia. Although DNA sequences have previously been studied using ancient DNA, the new technology that is available makes for clearer data. It has recently been discovered by Morten Allentoft of the University of Copenhagen’s Natural History Museum and his colleagues that light-skinned Europeans were present at a high frequency already in the Bronze Age, thus implying that light-skinnedness was first developed previous to 5,000 years ago. Another conclusion from their data tells that during the Mesolithic hunter-gatherer age, the presence of blue eyes was already established. 
     These data are set to answer the question, could there be a greater distribution of Neanderthal DNA in the genomes of Europeans and Asians? This is still unclear, however the findings suggests that these humans were settled into Europe and Asia before the Bronze Age.
     Something also interesting about the data is that 5,000 years ago, humans had not evolved the enzyme to break down lactose - the sugar found in milk. In an evolutionary perspective, this makes sense because ancient humans and - in fact, mammals in general - do not need to drink milk to survive after infancy, thus the lactose intolerance. When humans began to produce the enzyme to break down that indicated the start of domestication of animals which did not occur much before 5,000 years ago thanks to the data. 

     I personally think that this article is interesting because there are people who today are still lactose intolerant. The article tries to explain this as their ancestors did not drink much milk, thus never needing the enzyme to break down lactose. It is amazing how using the preserved DNA from bones that have been under the earth for so long can lead to vast discoveries like this. This discovery tells a lot about the time line of when humans became what we are today.

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