Two groups of archaic humans — Neanderthals and their enigmatic cousins, Denisovans — occupied Denisova Cave in the Altai region of Siberia almost continuously through relatively warm and cold periods over the past 200,000 years, according to two new studies published in the January 31, 2019 issue of the journal Nature: fossils and DNA traces of Denisovans are found from at least 200,000 to 50,000 years ago, and those of Neanderthals between...