Evidence for Human Evolution

EVIDENCE FOR HUMAN EVOLUTION

As with the evolution of other organisms, several fields of study are involved in how this worked over time. The fossil record was used traditionally but now genetics has largely taken its place in determining where humans came from. This study of human life and its origins is called anthropology or paleoanthropology.

The extant hominoids, those currently living, are humans, bonobos, chimpanzees, gorillas, gibbons, and orangutans. As mentioned, gibbons are our most distant relative, while bonobos and chimpanzees are our closed relatives. The similarities between chimpanzees and humans indicate the sharing of between 95 and 99 percent of DNA. Speciation was very drawn-out, however, in part because of inbreeding. Mitochondrial Eve loved around 200,000 years ago in Africa.

The fossil record for the divergence of gorillas, chimpanzees and hominins is lacking. The earliest fossils of the hominin type were Sahelanthropus and Orrorin genuses, which date back 7 million and 5.7 million years ago, respectively. They may or may not have been our direct ancestors but could represent another branch of apes. Australopithecus species arose about 4 million ears ago. They had descendants that were our ancestors. Lucy herself was an Australopithecus afarensis, found in Ethiopia. There are relatives of hers that were found in South Africa.

Homo habilis is the first of the Homo genus to come forth at around 2.8 million years ago. They used tools, which have been documented archaeologically. Most were tools made of stone. Encephalization began to evolve after that so that Homo erectus developed and emigrated from Africa about 1.9 million years ago. Later came Homo ergaster, who lived mainly in Africa. Homo erectus and Homo ergaster first used fire and had more complex tools to work with.

There are other species that have been found as later ancestors. These include Homo rhodesiensis, Homo antecessor, Homo heidelbergensis, and Homo neanderthalensis. The earliest Homo genus that had modern features entirely came out of the Middle Paleolithic period in Ethiopia. The Neanderthals and the Denisovans probably evolved from a type of Homo erectus that had already left Africa.

Hybridization or interbreeding is a part of human prehistory. There was Neanderthal-human interbreeding in the Middle Paleolithic and Upper Paleolithic eras. It probably also happened with the Denisovans. All of this points to a network of inheritance rather than a linear ascension from archaic man to modern man.