Homo habilis in the context of "Dmanisi skull 5"

Homo (from Latin homō 'human') is a genus of great ape (family Hominidae) that emerged from the early homininian genus Australopithecus, encompassing a single extant species, Homo sapiens (modern humans), along with a number of extinct species (e.g. Homo erectus and Homo neanderthalensis) classified as either ancestral or closely related to modern humans, collectively called archaic humans. Homo, together with the genus Paranthropus, is probably most closely related to the species Australopithecus africanus within Australopithecus. The closest living relatives of Homo are of the hominin genus Pan (chimpanzees and bonobos), with the ancestors of Pan and Homo estimated to have diverged around 5.7–11 million years ago during the Late Miocene.

The oldest member of the genus is Homo habilis, with fossil records of just over 2 million years ago. H. erectus appeared about 2 million years ago and spread throughout Africa (debatably as another species called Homo ergaster) and Eurasia in several migrations. The species was adaptive and successful, and persisted for more than a million years before gradually diverging into new species around 500,000 years ago.

The Neogene (/ˈniː.ədʒiːn/ NEE-ə-jeen,) is a geologic period and system that spans 20.45 million years from the end of the Paleogene Period 23.04 Ma (million years ago) to the beginning of the present Quaternary Period 2.58 Ma. It is the second period of the Cenozoic and the eleventh period of the Phanerozoic. The Neogene is sub-divided into two epochs, the earlier Miocene and the later Pliocene. Some geologists assert that the Neogene cannot be clearly delineated from the modern geological period, the Quaternary. The term "Neogene" was coined in 1853 by the Austrian palaeontologist Moritz Hörnes (1815–1868). The earlier term Tertiary Period was used to define the span of time now covered by Paleogene and Neogene and, despite no longer being recognized as a formal stratigraphic term, "Tertiary" still sometimes remains in informal use.

During this period, mammals and birds continued to evolve into modern forms, while other groups of life remained relatively unchanged. The first humans (Homo habilis) appeared in Africa near the end of the period. Some continental movements took place, the most significant event being the connection of North and South America at the Isthmus of Panama, late in the Pliocene. This cut off the warm ocean currents from the Pacific to the Atlantic Ocean, leaving only the Gulf Stream to transfer heat to the Arctic Ocean. The global climate cooled considerably throughout the Neogene, culminating in a series of continental glaciations in the Quaternary Period that followed.

Acheulean (/əˈʃuːliən/; also Acheulian and Mode II), from the French acheuléen after the type site of Saint-Acheul, is an archaeological industry of stone tool manufacture characterized by the distinctive oval and pear-shaped "hand axes" associated with Homo erectus and derived species such as Homo heidelbergensis.

Acheulean tools were produced during the Lower Palaeolithic era across Africa and much of West Asia, South Asia, East Asia and Europe, and are typically found with Homo erectus remains. It is thought that Acheulean technologies first developed about 2 million years ago, derived from the more primitive Oldowan technology associated with Homo habilis.The Acheulean includes at least the early part of the Middle Paleolithic. Its end is not well defined; if Sangoan (also known as Epi-Acheulean) is included, it may be taken to last until as late as 130,000 years ago. In Europe and Western Asia, early Neanderthals adopted Acheulean technology, transitioning to Mousterian by about 160,000 years ago.

D2700, also known as Dmanisi skull 3, is one of five skulls discovered in Dmanisi, Georgia in 2001 and classified as early Homo erectus. It is an almost complete skull and is in an exceptionally good condition. It was dated stratigraphically as about 1.8 million years old.

Since the publication of the Dmanisi skull 5 in 2013, all of the five Dmanisi skulls (Skull 3 included) have contributed to the ongoing debate on human taxonomy, with some experts proposing the re-categorization of Homo ergaster, and possibly even Homo habilis, as morphologically diverse subspecies of H. erectus.

LD 350-1 is the earliest known specimen of the genus Homo, dating to 2.75–2.8 million years ago (mya), found in the Ledi-Geraru site in the Afar Region of Ethiopia. The specimen was discovered in fossiliferous silts 10 m (33 ft) above the Gurumaha Tuff section of the site by Ethiopian palaeoanthropologist Chalachew Seyoum on 29 January 2013. It is currently unassigned to a species, and it is unclear if it represents the ancestor to H. habilis and H. rudolfensis which evolved around 2.4 mya.

Homo rudolfensis is an extinct species of archaic human from the Early Pleistocene of East Africa about 2 million years ago (mya). Because H. rudolfensis coexisted with several other hominins, it is debated what specimens can be confidently assigned to this species beyond the lectotype skull KNM-ER 1470 and other partial skull aspects. No bodily remains are definitively assigned to H. rudolfensis. Consequently, both its generic classification and validity are debated without any wide consensus, with some recommending the species to actually belong to the genus Australopithecus as A. rudolfensis or Kenyanthropus as K. rudolfensis, or that it is synonymous with the contemporaneous and anatomically similar H. habilis.

H. rudolfensis is distinguished from H. habilis by larger size, but it is also argued that this species actually consists of male H. habilis specimens, assuming that H. habilis was sexually dimorphic and males were much larger than females. Because no bodily remains are definitely identified, body size estimates are largely based on the stature of H. habilis. Using this, male H. rudolfensis may have averaged about 160 cm (5 ft 3 in) in height and 60 kg (130 lb) in weight, and females 150 cm (4 ft 11 in) and 51 kg (112 lb). KNM-ER 1470 had a brain volume of about 750 cc (46 cu in). Like other early Homo, H. rudolfensis had large cheek teeth and thick enamel.