hominin

Hominin is the term used in paleoanthropology to describe the members of the human lineage after its split from the lineage leading to chimpanzees. The group includes modern humans (Homo sapiens) and all extinct species more closely related to humans than to chimpanzees, extending from early australopiths through the genus Homo and its immediate ancestors.

Key traits: Bipedal locomotion is a defining feature, with skeletal changes in the pelvis, legs, and feet. Over time, the dentition shows reduced canines and overall dental simplification, while brain size increases relative to body mass. Tool use and material culture become increasingly complex.

Evolutionary history: The human-chimpanzee split occurred about 6–7 million years ago. Earliest putative hominins include Sahelanthropus tchadensis, Orrorin tugenensis, and Ardipithecus species. Australopithecines (Australopithecus and Paranthropus) thrived from about 4 to 2 million years ago. The genus Homo first appears around 2.8–2.4 million years ago, with Homo habilis and later Homo erectus dispersing beyond Africa. Later lineages include Homo heidelbergensis, Homo neanderthalensis, and Denisovans, with Homo sapiens arising in Africa around 300,000 years ago. Modern humans interbred with some archaic hominins, contributing to the genomes of present-day populations.

Taxonomy and debate: Definitions of hominin vary. Some classifications place Australopithecus and Paranthropus within Hominini or Homininae, while others reserve Hominini for Homo and close relatives. Ongoing discoveries continue to refine these boundaries and relationships within the human lineage.