Research looks at humans' lactose intolerance

Oct 22, 2014, 3:24 PM EDT
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Research conducted on the bones of ancient humans has shed light on the evolving ability of humans to digest lactose-based foods. It took 5,000 years after the introduction of farming for humans to be able to digest dairy. Live Science writes:

This research unexpectedly revealed that ancient Europeans started dairying thousands of years before they evolved genes to make the most of milk in adulthood, investigators added.
Scientists examined ancient DNA extracted from 13 individuals in archaeological burial sites unearthed during highway construction in the Great Hungarian Plain in Central Europe. This crossroads for Eastern and Western cultures experienced significant transformations in culture and technologyknown to have shaped European prehistory. The bones at the site span about 5,000 years, from 5,700 B.C. to 800 B.C., ranging across the Stone, Copper, Bronze and Iron Ages.
After several years of experimentation with a variety of kinds of bones, the researchers discovered the best place to recover ancient DNA for analysis in humans is the petrous bone, a pyramidal bone at the base of the skull. The name petrous comes from the Latin word "petrosus," meaning "stonelike." The petrous bone is the hardest bone in the human body and very dense, forming a protective case for the inner ear.
"The high-percentage DNA yield from the petrous bones exceeded those from other bones by up to 183-fold,"the study's joint senior author Ron Pinhasi, an archaeologist at University College Dublin in Ireland, said in a statement. "This gave us anywhere between 12 percent and almost 90 percent human DNA in our samples, compared to somewhere between 0 percent and 20 percent obtained from teeth, fingers and rib bones."
Though humans had been consuming dairy products since the Neolithic period, the researchers found that they did not develop the alleles necessary to break it down until the late Bronze Age, which ended around 1000 B.C. If you're lactose intolerant, you know that a creamy slice of cheese is sometimes too good to pass up, so you suffer through it anyway, just as the ancient Europeans did.
As hunter-gatherers and farmers intermarried, the skin pigmentation of humans lightened, but the researchers were surprised to see that this had no affect sicon increasing their tolerance toward lactose.
"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," lead researcher Ron Pinhasi stated.