I found this abstract maybe :
https://www.pnas.org/doi/abs/10.1073/pnas.1109300108 "(...)an unusual segment of DNA that extends for >31 kb on chromosome 4 seems to have introgressed into modern Africans from a now-extinct taxon that may have lived in central Africa"
That's fascinating stuff. Says introgression may have occured 35ky ago from a branch that split 700ky ago.