sentences:  Later Stone Age individuals excavated at Fingira Rock, Malawi, dated to around 6100 years ago (2/2 males), and at Mount Hora, Malawi, dated to around 8000 years ago (1/1 males), all belonged to Y haplogroup BT(xCT) (i.e.they did not belong to haplogroup CT but may have belonged to haplogroup B).The ISOGG tree since 2014 has treated M91 as the defining mutation of BT.