Deeply divergent archaic mitochondrial genome provides lower time boundary for African gene flow into Neanderthals | Nature Communications
https://www.nature.com/articles/ncomms16046
In Neanderthal DNA, Signs of a Mysterious Human Migration - The New York Times
https://www.nytimes.com/2017/07/04/science/neanderthals-dna-homo-sapiens-human-evolution.html