What is The human lineage?

The human lineage is the clade of all species closer to modern humans than to the chimpanzee: everything descended from the human side of the six-million-year node. It contains one living species, Homo sapiens, and a score of fossil ones — the australopithecines and the several species of the genus Homo. A fossil belongs to it if it shows derived characters of the lineage: upright walking, a shortened face, small canines, and later a large brain and tools.