Analysis of the entire genome of a 7,000 year old hunter-gatherer has revealed interesting facts about the evolution of human genes. DNA extracted from the teeth of remains found in a cave in Spain were completely sequenced. This marks the first pre-agricultural genome to be sequenced and analyzed. While previous sequence data have shown changes in genes associated with early agriculture, such as adaptations to lactose, grain, livestock diseases, the new data raises interesting questions about when some of these genes evolved.
Indeed, the hunter gatherer was lactose-intolerant. This supports previous hypotheses that adult tolerance of lactose, associated with keeping livestock and drinking milk, evolved later (farming became common in Spain 6,000 years ago). Other hypotheses, such as the notion that hunter-gatherers had weaker immune systems and, in Europe, had lighter skin, have been disproven. In fact, the hunter-gatherer had a strong immune system, contrary to hypotheses that a robust immune system evolved when livestock, and their diseases, were kept in close proximity to humans on farms. Maybe a robust immune system evolved in response to water-borne diseases (giardia, cholera, etc.)?
Perhaps most interesting, the hunter-gatherer had the genes for darkly pigmented skin & hair, like his African ancestors, but also blue eyes. Some hypotheses about skin and eye color suggested that lighter skin came first, then eye color. It makes sense that lighter skin evolved in more polar areas, as the lower intensity of sunlight causes a lack of vitamin D. Perhaps blue eyes were chosen earlier during mate selection?
Read the New Scientist article HERE.
Read the full Nature article HERE.
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