Timeline of human evolution. Ancestral Lines. Evolutionary biologists use a cladogram, the treelike diagram of evolutionary branches or clades, to organize species into lines of evolutionary descent across time.
Biologists use three types of evidence to deduce evolutionary connections: genetics, morphology, and geologic dating. (Behavior, normally a key part of evolutionary studies, can only be inferred in extinct species — for example, by examining the ecology in which the species flourished and the species adaptations for eating and locomotion.) Analyses of primate fossils and the genetic relatedness of living primates converge to the conclusion that humans and chimpanzees branched from a common ancestor about 7 million years ago. DNA recovered from several uncontaminated Neanderthalensis fossils indicated that modern humans and extinct neanderthals diverged about 400,000 years ago; but more recent studies show that they must have interbred within Europe or the Middle East since then. Evolution: Humans: Origins of Humankind.
Human Family Tree.