Қазылған ертедегі адам – Homo rudolfensis

Extinct hominin from the Early Pleistocene of East Africa

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 in height and in weight, and females and KNM ER 1470 had a brain volume of about Like other early Homo, H. rudolfensis had large cheek teeth and thick enamel. Early Homo species exhibit marked brain growth compared to Australopithecus predecessors, which is typically explained as a change in diet with a calorie rich food source, namely meat. Though not associated with tools, dental anatomy suggests some processing of plant or meat fiber before consumption, though the mouth could still effectively chew through mechanically challenging food, indicating tool use did not greatly affect diet.

The first fossils were discovered in 1972 along Lake Turkana (at the time called Lake Rudolf) in Kenya, and were detailed by Kenyan palaeoanthropologist Richard Leakey the following year. The specimens were: a large and nearly complete skull (KNM ER 1470, the lectotype) discovered by Bernard Ngeneo, a local; a right femur (KNM ER 1472) discovered by J. Harris; an upper femur (proximal) fragment (KNM ER 1475) discovered by fossil collector Kamoya Kimeu; and a complete left femur (KNM ER 1481) discovered by Harris. However, it is unclear if the femora belong to the same species as the skull. Leakey classified them under the genus Homo because he had reconstructed the skull fragments so that it had a large brain volume and a flat face, but did not assign them to a species. Because the horizon they were discovered in was, at the time, dated to 2.9–2.6 million years ago (mya), Leakey thought these specimens were a very early human ancestor. This challenged the major model of human evolution at the time where Australopithecus africanus gave rise to Homo about 2.5 mya, but if Homo had already existed at this time, it would call for serious revisions. However, the area was redated to about 2 mya in 1977 (the same time period as H. habilis and H. ergaster/H. erectus), and more precisely to 2.1–1.95 mya in 2012. They were first assigned to the species habilis in 1975 by anthropologists Colin Groves and Vratislav Mazák. In 1978, in a joint paper with Leakey and English anthropologist Alan Walker, Walker suggested the remains belong in Australopithecus (and that the skull was incorrectly reconstructed), but Leakey still believed they belonged to Homo, though they both agreed that the remains could belong to habilis. KNM ER 1470 was much larger than the Olduvai remains, so the terms H. habilis sensu lato ("in the broad sense") and H. habilis sensu stricto ("in the strict sense") were used to include or exclude the larger morph, respectively. In 1986, the remains were placed into a new species, rudolfensis, by Russian anthropologist Valery Alekseyev (but he used the genus Pithecanthropus, which was changed to Homo three years later by Groves). In 1999, Kennedy argued that the name was invalid because Alekseyev had not assigned a holotype. Pointing out that this is in fact not mandatory, Wood the same year nevertheless designated KNM ER 1470 as the lectotype. In 1999, Wood and biological anthropologist Mark Collard recommended moving rudolfensis and habilis to Australopithecus based on the similarity of dental adaptations. However, they conceded that dental anatomy is highly variable among hominins and not always reliable when formulating family trees. In 2003, Australian anthropologist David Cameron concluded that the earlier australopithecine Kenyanthropus platyops was the ancestor of rudolfensis, and reclassified it as K. rudolfensis. He also believed that Kenyanthropus was more closely related to Paranthropus than Homo. In 2008, a re reconstruction of the skull concluded it was incorrectly restored originally, though agreed with the classification as H. rudolfensis. but American palaeoanthropologist Tim D. White believes this to be premature because it is unclear how wide the range of variation is in early hominins. There is still no wide consensus on how rudolfensis and habilis relate to H. ergaster and descendent species. Beyond KNM ER 1470, there is disagreement on which specimens actually belong in H. rudolfensis as it is difficult to assign with accuracy remains that do not preserve the face and jaw. No H. rudolfensis bodily elements have been definitively associated with a skull and thus to the species. Nonetheless, H. rudolfensis and H. habilis generally are recognised members of the genus at the base of the family tree, with arguments for synonymisation or removal from the genus not widely adopted. Though it is now largely agreed upon that Homo evolved from Australopithecus, the timing and placement of this split has been much debated, with many Australopithecus species having been proposed as the ancestor. The discovery of LD 350 1, the oldest Homo specimen, dating to 2.8 mya, in the Afar Region of Ethiopia may indicate that the genus evolved from A. afarensis around this time. The species LD 350 1 belongs to could be the ancestor of H. rudolfensis and H. habilis, but this is unclear. Based on 2.1 million year old stone tools from Shangchen, China, possibly an ancestral species to H. rudolfensis and H. habilis dispersed across Asia.

In 1973, Mr. Leakey had reconstructed the skull KNM ER 1470 with a flat face and a brain volume of For comparison, H. habilis specimens average about , and H. ergaster Bromage and colleagues returned in 2008 with a revised skull reconstruction and brain volume estimate of
[[File:HPCR UR 501 01. jpg|thumb|UR 501, the oldest H. rudolfensis specimen

Body size estimates of H. rudolfensis and H. habilis typically conclude a small size comparable to australopithecines. These largely depend on the H. habilis partial skeleton OH 62 estimated at in height and in weight. H. rudolfensis is thought to be bigger than H. habilis, but it is unclear how big this species was as no bodily elements have been definitively associated with a skull. Based on just the KNM ER 1470 skull, male H. rudolfensis were estimated to have been in height and in weight, and females and
For specimens that might be H. rudolfensis: the femur KNM ER 1472 which may also be H. habilis or H. ergaster was estimated at and , the humerus KNM ER 1473 and , the partial leg KNM ER 1481 which may also be H. ergaster and , the pelvis KNM ER 3228 which may also be H. ergaster and , and the femur KNM ER 3728 which may be H. habilis or P. boisei and The juvenile specimen KNM ER 62000, a partial face, has the same age landmarks as a 13 to 14 year old modern human, but more likely died at around 8 years of age due to the presumed faster growth rate among early hominins based on dental development rate. Large incisor size in H. rudolfensis and H. habilis compared to Australopithecus predecessors implies these two species relied on incisors more. The large, Australopithecus like molars could indicate more mechanically challenging food compared to later Homo. The bodies of the mandibles of H. rudolfensis and other early Homo are thicker than those of modern humans and all living apes, more comparable to Australopithecus. The mandibular body resists torsion from the bite force or chewing, meaning their jaws could produce unusually powerful stresses while eating. Early H. rudolfensis and Paranthropus have exceptionally thick molars for hominins, and the emergence of these two coincides with a cooling and aridity trend in Africa about 2.5 mya. This could mean they evolved due to climate change. Nonetheless, in East Africa, tropical forests and woodlands still persisted through periods of drought. H. rudolfensis coexisted with H. habilis, H. ergaster, and P. boisei.