Describe the stages of human evolution and mention the major hominid forms giving their time of origin.

Early Hominids (7 million – 4 million years ago)

The earliest hominids emerged in Africa during the Miocene epoch. These were apelike creatures exhibiting the first signs of hominin characteristics, most notably bipedalism. Defining a ‘hominid’ (or hominin) is crucial – it refers to members of the taxonomic family Hominidae, which includes all species more closely related to humans than to chimpanzees.

• Sahelanthropus tchadensis (7-6 million years ago): Discovered in Chad, this species is one of the oldest known possible hominins. Its foramen magnum (the hole at the base of the skull where the spinal cord connects) suggests bipedalism.
• Orrorin tugenensis (6 million years ago): Found in Kenya, evidence suggests this species also walked upright.
• Ardipithecus ramidus (4.4 million years ago): ‘Ardi’ was discovered in Ethiopia and exhibited a mix of arboreal (tree-dwelling) and bipedal traits. It possessed a grasping big toe, indicating tree climbing, but its pelvis suggests efficient bipedal walking.

Australopithecines (4 million – 2 million years ago)

Australopithecines were a diverse group of hominins that were fully bipedal, though still retaining some apelike features. They had smaller brains than modern humans.

• Australopithecus anamensis (4.2-3.9 million years ago): Considered a likely ancestor to *A. afarensis*.
• Australopithecus afarensis (3.9-2.9 million years ago): ‘Lucy’, a remarkably complete fossil, belongs to this species. They were bipedal but had relatively small brains and long arms, suggesting some arboreal activity.
• Australopithecus africanus (3-2 million years ago): Found in South Africa, this species had a slightly larger brain capacity than *A. afarensis*.
• Paranthropus robustus & boisei (2-1.2 million years ago): These were ‘robust’ australopithecines with massive jaws and teeth, adapted for chewing tough vegetation. They represent an evolutionary side branch that did not lead to *Homo*.

The Genus *Homo* (2.8 million years ago – Present)

The emergence of the genus *Homo* marked significant advancements in brain size, tool use, and social complexity.

• Homo habilis (2.8-1.5 million years ago): Often called ‘handy man’ due to its association with the Oldowan tool industry – the earliest known stone tools. They had larger brains than australopithecines.
• Homo erectus (1.9 million – 117,000 years ago): A highly successful species that migrated out of Africa and spread to Asia. *Homo erectus* had a larger brain capacity, used more sophisticated tools (Acheulean industry), and likely controlled fire.
• Homo heidelbergensis (700,000 – 200,000 years ago): Considered a likely ancestor to both Neanderthals and *Homo sapiens*. They were skilled hunters and may have built shelters.
• Homo neanderthalensis (400,000 – 40,000 years ago): Neanderthals were adapted to cold climates and inhabited Europe and parts of Asia. They had large brains, strong bodies, and sophisticated tools. Evidence suggests they engaged in symbolic behavior, such as burial rituals.
• Homo sapiens (300,000 years ago – Present): Modern humans originated in Africa and eventually spread across the globe. *Homo sapiens* are characterized by a high forehead, a chin, and a complex culture.

Hominid Species	Time of Origin (approx.)	Key Characteristics
*Australopithecus afarensis*	3.9-2.9 million years ago	Bipedal, small brain, long arms
*Homo habilis*	2.8-1.5 million years ago	Larger brain, used Oldowan tools
*Homo erectus*	1.9 million – 117,000 years ago	Larger brain, Acheulean tools, controlled fire, migrated out of Africa
*Homo neanderthalensis*	400,000 – 40,000 years ago	Large brain, adapted to cold climates, sophisticated tools, symbolic behavior
*Homo sapiens*	300,000 years ago – Present	High forehead, chin, complex culture