Research has shown that all humans started from a common group of ancestors in Africa, but the early European settlers in Minnesota looked vastly different from ancient African humans. Now, a new study has shown that the transition from a hunter-gatherer lifestyle to a farming lifestyle had a huge impact on the genes, and looks, of modern-day Europeans (and their descendants in Minnesota).
The research team, led by Carles Lalueza-Fox of the University of Barcelona, Spain, published their study this week in the journal Nature. The group used DNA sequencing of a skeleton of a man who lived almost 8,000 years ago. The skeleton was found in a cave in Spain, and it was determined that the man belonged to a tribe of hunter-gatherers. Before, Lalueza-Fox had only sequenced the mitochondrial DNA of the skeleton, but this new study sequenced the man's entire set of DNA from the nucleus. The mitochondria is the powerhouse of the cell, a small factory for energy. Mitochondrial DNA sequencing is useful in determining lineage because mitochondria are passed down from mother to child, but it carries only a small number of genes. The nucleus of a cell is where the majority of a person's genes are housed, so a much more detailed picture of the ancient man emerged from this new study.
The DNA from the hunter-gatherer skeleton was compared with the DNA of modern-day Europeans. The first thing that surprised Lalueza-Fox was that the man had genes indicating blue eyes and dark skin. Although many modern-day Europeans have blue eyes, their skin color has become considerably lighter. For a long time, researchers thought that this was due to their movement northward - decreasing amounts of sunlight meant that their skin had to adapt to be able to absorb more vitamin D - but this new piece of information led Lalueza-Fox to conclude that the change in skin color was more likely due to the change in diet. Hunter-gatherers ate more meat, which is rich in vitamin D, while early farmers had little access to meat and ate a diet much more rich in carbohydrates. This change in diet leading to a change in genes was also supported by another difference in the skeleton's DNA. The hunter-gatherer's DNA showed that the genes for breaking down lactose (a sugar found in milk) and starch (the carbohydrate found in most crops) were undeveloped compared to modern DNA.
Other surprises included a much more developed immune system, and a striking similarity to other hunter-gatherer skeletons from the same time period. The larger picture that has emerged from this study is that the hunter-gatherers were probably a much more cohesive group than originally thought, and that their change in lifestyle led to many physical and genetic changes as well.