We know about early Homo sapiens sapiens mating with Neanderthals and the Denisovans, but now scientists have discovered that there may be another species... from NPR: 'Ghost' DNA In West Africans Complicates Story Of Human Origins, https://www.npr.org/2020/02/12/805237120/ghost-dna-in-west-africans-complicates-story-of-human-origins