Answer to Question #110126 in Evolution for NIBEDITA RUDRA

Question

Outline the hominid lineage upto modern human and discuss the major evidences that support it.

Answer 1

The human evolutionary family tree.

Resourse: Overview of Hominin Evolution

By: Herman Pontzer (Dept. of Anthropology, Hunter College; New York Consortium for Evolutionary Primatology) © 2012 Nature Education 

Citation: Pontzer, H. (2012) Overview of Hominin Evolution. Nature Education Knowledge 3(10):8

Evolutionary family is comprised of the hominoids, the group of primates that includes the "lesser apes" (siamangs and gibbons) as well as the "great apes" (chimpanzees, bonobos, gorillas, and orangutans)

Species' evolution began in Africa, near the end of the geological time period known as the Miocene, just before our lineage diverged from that of chimpanzees and bonobos.

The first human-like traits to appear in the hominin fossil record are bipedal walking and smaller, blunt canines.

The oldest hominins currently known are Sahelanthropus tchadensis from Chad and Orrorin tugenensis from Kenya. By far the best known early hominin is Ardipithecus ramidus, a 4.4 million year old species from Ethiopia, which is known from a nearly complete skeleton as well as numerous other dental and skeletal remains

 Early hominins and Australopithecus retained ape-size brains. Bipedal walking evolved very early in the hominin lineage, but Ardipithecus (and possibly other early hominins) retained a grasping foot that may have diminished bipedal efficiency. Reduced canine size also evolved early in the hominin lineage, although early hominin canines were larger and more pointed than those of later hominins. Molar size increased with Australopithecus but later is reduced in Homo.

Australopithecus was a highly successful genus that persisted for nearly three million years. The earliest fossils of our own genus, Homo, are found in East Africa and dated to 2.3 mya (Kimbel et al. 1997). These early specimens are similar in brain and body size to Australopithecus, but show differences in their molar teeth, suggesting a change in diet.

The oldest member of the genus Homo, H. habilis (2.3–1.4 mya) is found in East Africa and is associated with butchered animal bones and simple stone tools. Its more formidable and widespread descendant, H. erectus, is found throughout Africa and Eurasia and persisted from 1.9 mya to 100 kya. Like modern humans, H. erectus lacked the forelimb adaptations for climbing seen in Australopithecus. H. erectus in Africa gave rise to H. heidelbergensis, a species very much like us in terms of body proportions, dental adaptations, and cognitive ability.

Neanderthals (H. neanderthalensis), cold-adapted hominins with stout physiques, complex behaviors, and brains similar in size to ours, are thought to have evolved from H. heidelbergensis populations in Europe by at least 250 kya.

Fossil and DNA evidence suggest our own species, H. sapiens, evolved in Africa 200 kya, probably from H. heidelbergensis. The increased behavioral sophistication of H. sapiens, as indicated by our large brains and archeological evidence of a broader tool set and clever hunting techniques, allowed our species to flourish and grow on the African continent.

The evolution of our species from an ape-like Miocene ancestor was a complex process. Some human traits, like bipedalism, evolved very early, while others, like large brains, did not evolve until relatively recently. And that is evidence of evolutionary line of hominids to H. sapiens.