A study has found that DNA belonging to two Neanderthals, who were found in the same Siberian cave about 10,000 years apart, were likely cousins. The study compared DNA extracted from a 110,000-year-old bone fragment from a male Neanderthal and compared it with previously discovered DNA from an older female. The genetic similarity indicated that Neanderthal populations in the Altai region likely lived in groups of fewer than 50 people, which led to rapid evolution of the Neanderthal gene frequency differences. The researchers also found traces of Denisovan DNA in both D17 and D5, presenting a fourth, previously unknown Neanderthal genome. The large genetic separation may have limited the Neanderthropes' ability to adapt to environmental changes.