Homo habilis (lit. 'handy man') is an extinctspecies ofarchaic human from theEarly Pleistocene of East and South Africa about 2.4 million years ago to 1.65 million years ago (mya). It is among the oldest species of archaic humans.[2][3] Suggestions for pushing back the age to 2.8 Mya were made in 2015 based on the discovery ofa jawbone.[4] Upon species description in 1964,H. habilis was highly contested, with many researchers recommending it besynonymised withAustralopithecus africanus, the only other earlyhominin known at the time, butH. habilis received more recognition as time went on and more relevant discoveries were made. By the 1980s,H. habilis was proposed to have been a human ancestor, directly evolving intoHomo erectus, which directly led to modern humans. This viewpoint is now debated. Several specimens with insecure species identification were assigned toH. habilis, leading to arguments for splitting, namely into "H. rudolfensis" and "H. gautengensis" of which only the former has received wide support.
H. habilis brain size generally varied from 500 to 900 cm3 (31–55 cu in). The body proportions ofH. habilis are only known from two highly fragmentary skeletons, and is based largely on assuming a similar anatomy to the earlieraustralopithecines. Because of this, it has also been proposedH. habilis be moved to thegenusAustralopithecus asAustralopithecus habilis. However, the interpretation ofH. habilis as a small-statured human with inefficient long-distance travel capabilities has been challenged. The presumed female specimen OH 62 is traditionally interpreted as having been 100–120 cm (3 ft 3 in – 3 ft 11 in) in height and 20–37 kg (44–82 lb) in weight assuming australopithecine-like proportions, but assuming humanlike proportions she would have been about 148 cm (4 ft 10 in) and 35 kg (77 lb). Nonetheless,Homo habilis may have been at least partiallyarboreal like what is postulated for australopithecines. Early hominins are typically reconstructed as having thick hair and markedsexual dimorphism with males much larger than females, though relative male and female size is not definitively known.
H. habilis manufactured theOldowan stone tool industry and mainly used tools in butchering. EarlyHomo, compared to australopithecines, are generally thought to have consumed high quantities of meat and, in the case ofH. habilis, scavenged meat. Typically, early hominins are interpreted as having lived inpolygynous societies, though this is highly speculative. AssumingH. habilis society was similar to that of modern savannachimpanzees andbaboons, groups may have numbered 70–85 members. This configuration would be advantageous with multiple males to defend against open savanna predators, such as big cats, hyenas and crocodiles.H. habilis coexisted withH. rudolfensis,H. ergaster / H. erectus andParanthropus boisei.
The first recognised remains—OH 7, partial juvenile skull, hand, and foot bones dating to 1.75 million years ago (mya)—were discovered inOlduvai Gorge,Tanzania, in 1960 by Jonathan Leakey, with other native Africans who dug into Olduvai Gorge, and who worked for Jonathan Leakey. However, the actual first remains—OH 4, a molar—were discovered by the senior assistant ofLouis andMary Leakey (Jonathan's parents), Heselon Mukiri, other native Africans, in 1959, but this was not realised at the time.[5] By this time, the Leakeys had spent 29 years excavating in Olduvai Gorge for earlyhominin remains, but had instead recovered mainly other animal remains as well as theOldowanstone-toolindustry. The industry had been ascribed toParanthropus boisei (at the time "Zinjanthropus") in 1959 as it was the first and only hominin recovered in the area, but this was revised upon OH 7's discovery.[5] In 1964, Louis, South African palaeoanthropologistPhillip V. Tobias, and British primatologistJohn R. Napier officially assigned the remains into thegenusHomo, and, on recommendation by Australian anthropologistRaymond Dart, thespecific nameH. habilis, meaning "able, handy, mentally skillful, vigorous" inLatin.[6] The specimen's association with the Oldowan (then considered evidence of advanced cognitive ability) was also used as justification for classifying it intoHomo.[7] OH 7 was designated theholotype specimen.[6]
After description, it was hotly debated ifH. habilis should be reclassified intoAustralopithecus africanus (the only other early hominin known at the time), in part because the remains were so old and at the timeHomo was presumed to have evolved in Asia (with the australopithecines having no living descendants). Also, the brain size was smaller than whatWilfrid Le Gros Clark proposed in 1955 when consideringHomo.[5][8] The classificationH. habilis began to receive wider acceptance as more fossil elements and species were unearthed.[5] In 1983, Tobias proposed thatA. africanus was a direct ancestor ofParanthropus andHomo (the two weresister taxa), and thatA. africanus evolved intoH. habilis which evolved intoH. erectus which evolved into modern humans (by a process ofcladogenesis). He further said that there was a major evolutionary leap betweenA. africanus andH. habilis, and thereupon human evolution progressed gradually becauseH. habilis brain size had nearly doubled compared to australopithecine predecessors.[9]
Many had accepted Tobias' model and assignedLate Pliocene toEarly Pleistocene hominin remains outside the range ofParanthropus andH. erectus intoH. habilis. For non-skull elements, this was done on the basis of size as there was a lack of clear diagnostic characteristics.[10] Because of these practices, the range of variation for the species became quite wide, and the termsH. habilissensu stricto (i.e. strictly) andH. habilissensu lato (i.e. broadly) were in use to exclude and include, respectively, more discrepant morphs. To address this controversy, English palaeoanthropologist Bernard Wood proposed in 1985, that the comparatively massive skull KNM-ER 1470 fromLake Turkana, Kenya, discovered in 1972 and assigned toH. habilis, actually represented a different species,[11] now referred to asHomo rudolfensis. It is also argued that instead it represents a male specimen whereas otherH. habilis specimens are female.[12] EarlyHomo from South Africa have variously been assigned toH. habilis orH. ergaster / H. erectus, but species designation has largely been unclear. In 2010, Australian archaeologist Darren Curoe proposed splitting off South African earlyHomo into a new species, "Homo gautengensis".[13]
In 1986, OH 62, a fragmentary skeleton was discovered by American anthropologistTim D. White in association withH. habilis skull fragments, definitively establishing aspects ofH. habilis skeletal anatomy for the first time, and revealing moreAustralopithecus-like thanHomo-like features.[10] Because of this, as well as similarities in dental adaptations, Wood and biological anthropologist Mark Collard suggested moving the species toAustralopithecus in 1999.[14][15][16][17] However, reevaluation of OH 62 to a more humanlike physiology, if correct, would cast doubt on this.[18] The discovery of the 1.8 Ma GeorgianDmanisi skulls in the early 2000s, which exhibit several similarities with earlyHomo, has led to suggestions that all contemporary groups of earlyHomo in Africa, includingH. habilis andH. rudolfensis, are the same species and should be assigned toH. erectus.[19][20]
Homo family tree showingH. habilis andH. rudolfensis at the base as offshoots of the human line[21]
There is still no wide consensus as to whether or notH. habilis is ancestral toH. ergaster / H. erectus or is an offshoot of the human line,[22] and whether or not all specimens assigned toH. habilis are correctly assigned or the species is an assemblage of differentAustralopithecus andHomo species.[23] Studies of the dental morphology ofH. habilis have suggested that it shares greater similarity withAustralopithecus than with laterHomo species.[24] Nonetheless,H. habilis andH. rudolfensis 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.[25]
Though it is now largely agreed upon thatHomo evolved fromAustralopithecus, the timing and placement of this split has been much debated, with manyAustralopithecus species having been proposed as the ancestor. The discovery ofLD 350-1, the oldestHomo specimen, dating to 2.8 mya, in theAfar Region of Ethiopia may indicate that the genus evolved fromA. afarensis around this time. This specimen was initially classified asHomo sp.,[26] though subsequent studies have suggested that it also shares characteristics withAustralopithecus and that it is clearly distinct fromH. habilis.[27][28] The oldestH. habilis specimen, A.L. 666-1, dates to 2.3 mya, but is anatomically morederived (has less ancestral, or basal, traits) than the younger OH 7, suggesting derived and basal morphs lived concurrently, and that theH. habilis lineage began before 2.3 mya.[29] Based on 2.1-million-year-old stone tools fromShangchen, China,H. habilis or an ancestral species may have dispersed across Asia.[30] The youngestH. habilis specimen, OH 13, dates to about 1.65 mya.[29]
It has generally been thought that brain size increased along the human line especially rapidly at the transition between species, withH. habilis brain size smaller than that ofH. ergaster / H. erectus, jumping from about 600–650 cc (37–40 cu in) inH. habilis to about 900–1,000 cc (55–61 cu in) inH. ergaster andH. erectus.[29][31] However, a 2015 study showed that the brain sizes ofH. habilis,H. rudolfensis, andH. ergaster generally ranged between 500–900 cc (31–55 cu in) after reappraising the brain volume of OH 7 from 647–687 cc (39.5–41.9 cu in) to 729–824 cc (44.5–50.3 cu in).[29] This does, nonetheless, indicate a jump from australopithecine brain size which generally ranged from 400–500 cc (24–31 cu in).[31]
The brain anatomy of allHomo features an expandedcerebrum in comparison to australopithecines. The pattern of striations on the teeth of OH 65 slant right, which may have been accidentally self-inflicted when the individual was pulling a piece of meat with its teeth and the left hand while trying to cut it with a stone tool using the right hand. If correct, this could indicate righthandedness, and handedness is associated with major reorganisation of the brain and thelateralisation of brain function between the left and right hemispheres. This scenario has also been hypothesised for some Neanderthal specimens. Lateralisation could be implicated in tool use. In modern humans, lateralisation is weakly associated with language.[32]
The tooth rows ofH. habilis were V-shaped as opposed to U-shaped in laterHomo, and the mouth jutted outwards (wasprognathic), though the face was flat from the nose up.[29]
Based on the fragmentary skeletons OH 62 (presumed female) and KNM-ER 3735 (presumed male),H. habilis body anatomy has generally been considered to have been more apelike than even that of the earlierA. afarensis; this is consistent with an at least partiallyarboreal lifestyle in the trees as is assumed in australopithecines. Based on OH 62 and assuming comparable body dimensions to australopithecines,H. habilis has generally been interpreted as having been small-bodied like australopithecines, with OH 62 generally estimated at 100–120 cm (3 ft 3 in – 3 ft 11 in) in height and 20–37 kg (44–82 lb) in weight. However, assuming longer, modern humanlike legs, OH 62 would have been about 148 cm (4 ft 10 in) and 35 kg (77 lb), and KNM-ER 3735 about the same size.[33] For comparison, modern human men and women in the year 1900 averaged 163 cm (5 ft 4 in) and 152.7 cm (5.01 ft), respectively.[34] It is generally assumed that pre-H. ergaster hominins, includingH. habilis, exhibited notablesexual dimorphism with males markedly bigger than females. However, relative female body mass is unknown in this species.[35]
Early hominins, includingH. habilis, are thought to have had thick body hair coverage like modern non-human apes because they appear to have inhabited colder regions and are thought to have had a less active lifestyle than (presumed hairless) post-ergaster species. Consequently, they probably required thick body hair to stay warm.[36] Based on dental development rates,H. habilis is assumed to have had an accelerated growth rate compared to modern humans, more like that of modern non-human apes.[37]
The arms ofH. habilis and australopithecines have generally been considered to have been proportionally long and so adapted for climbing and swinging.[38][39][40] In 2004, anthropologists Martin Haeusler andHenry McHenry argued that, because thehumerus tofemur ratio of OH 62 is within the range of variation for modern humans, and KNM-ER 3735 is close to the modern human average, it is unsafe to assume apelike proportions. Nonetheless, the humerus of OH 62 measured 258–270 mm (10.2–10.6 in) long and theulna (forearm) 245–255 mm (9.6–10.0 in), which is closer to the proportion seen in chimpanzees. The hand bones of OH 7 suggest precision gripping, important in dexterity, as well as adaptations for climbing. In regard to the femur, traditionally comparisons with theA. afarensis specimen AL 288-1 have been used to reconstruct stout legs forH. habilis, but Haeusler and McHenry suggested the more gracile OH 24 femur (either belonging toH. ergaster / H. erectus orP. boisei) may be a more apt comparison. In this instance,H. habilis would have had longer, humanlike legs and have been effective long-distance travellers as is assumed to have been the case inH. ergaster.[18] However, estimating the unpreserved length of a fossil is highly problematic. The thickness of the limb bones in OH 62 is more similar to chimpanzees thanH. ergaster / H. erectus and modern humans, which may indicate different load bearing capabilities more suitable for arboreality inH. habilis.[41] The strongfibula of OH 35 (though this may belong toP. boisei) is more like that of non-human apes, and consistent with arboreality and vertical climbing.[42]
OH 8, a foot, is better suited for terrestrial movement than the foot ofA. afarensis, though it still retains many apelike features consistent with climbing.[18] However, the foot has projected toe bone and compacted mid-foot joint structures, which restrict rotation between the foot and ankle as well as at the front foot. Foot stability enhances the efficiency of force transfer between the leg and the foot and vice versa, and is implicated in theplantar arch elastic spring mechanism which generates energy while running (but not walking). This could possibly indicateH. habilis was capable of some degree ofendurance running, which is typically thought to have evolved later inH. ergaster / H. erectus.[43]
Typically,H. ergaster / H. erectus is considered to have been the first human to have lived in amonogamous society, and all preceding hominins werepolygynous. However, it is highly difficult to speculate with any confidence the group dynamics of early hominins.[44] The degree ofsexual dimorphism and the size disparity between males and females is often used to correlate between polygyny with high disparity and monogamy with low disparity based on general trends (though not without exceptions) seen in modern primates. Rates of sexual dimorphism are difficult to determine as early hominin anatomy is poorly represented in the fossil record. In some cases, sex is arbitrarily determined in large part based on perceived size and apparent robustness in the absence of more reliable elements in sex identification (namely the pelvis). Mating systems are also based on dental anatomy, but early hominins possess a mosaic anatomy of different traits not seen together in modern primates; the enlarged cheek teeth would suggest marked size-related dimorphism and thus intense male–male conflict over mates and a polygynous society, but the small canines should indicate the opposite. Other selective pressures, including diet, can also dramatically impact dental anatomy.[44] The spatial distribution of tools and processed animal bones at the FLK Zinj and PTK sites in Olduvai Gorge indicate the inhabitants used this area as a communal butchering and eating grounds, as opposed to thenuclear family system of modern hunter gatherers where the group is subdivided into smaller units each with their own butchering and eating grounds.[45]
The behaviour of earlyHomo, includingH. habilis, is sometimes modelled on that of savanna chimps andbaboons. These communities consist of several males (as opposed to aharem society) in order to defend the group on the dangerous and exposed habitat, sometimes engaging in a group display of throwing sticks and stones against enemies and predators.[46] The left foot OH 8 seems to have been bitten off by a crocodile,[47] possiblyCrocodylus anthropophagus,[48] and the leg OH 35, which either belongs toP. boisei orH. habilis, shows evidence ofleopard predation.[47]H. habilis and contemporary hominins were likely predated upon by other large carnivores of the time, such as (in Olduvai Gorge) thehunting hyenaChasmaporthetes nitidula, and the saber-toothed catsDinofelis andMegantereon.[49] In 1993, American palaeoanthropologistLeslie C. Aiello and British evolutionary psychologistRobin Dunbar estimated thatH. habilis group size ranged from 70–85 members—on the upper end of chimp and baboon group size—based on trends seen inneocortex size and group size in modern non-human primates.[50]
H. habilis coexisted withH. rudolfensis,H. ergaster / H. erectus, andP. boisei. It is unclear how all of these species interacted.[5][51][52] To explain whyP. boisei was associated with Olduwan tools despite not being theknapper (the one who made the tools), Leakey and colleagues, when describingH. habilis, suggested that one possibility wasP. boisei was killed byH. habilis,[6] perhaps as food.[7] However, when describingP. boisei five years earlier, Louis Leakey said, "There is no reason whatever, in this case, to believe thatthe skull represents the victim of a cannibalistic feast by some hypothetical more advanced type of man."[53]
It is thoughtH. habilis derived meat from scavenging rather than hunting (scavenger hypothesis), acting as a confrontational scavenger and stealing kills from smaller predators such asjackals orcheetahs.[54] Fruit was likely also an important dietary component, indicated by dental erosion consistent with repetitive exposure to acidity.[55] Based ondental microwear-texture analysis,H. habilis (like other earlyHomo) likely did not regularly consume tough foods. Microwear-texture complexity is, on average, somewhere between that of tough-food eaters and leaf eaters (folivores),[56] and points to an increasinglygeneralised andomnivorous diet.[57] Freshwater fish likely were also consumed, evidenced by the findings of fish remains at archaeological sites most likely associated withH. habilis.[58]
It is typically thought that the diets ofH. habilis and other earlyHomo had a greater proportion of meat thanAustralopithecus, and that this led to brain growth. The main hypotheses regarding this are: meat is energy- and nutrient-rich and put evolutionary pressure on developing enhanced cognitive skills to facilitate strategic scavenging and monopolise fresh carcasses, or meat allowed the large and calorie-expensive ape gut to decrease in size allowing this energy to be diverted to brain growth. Alternatively, it is also suggested that earlyHomo, in a drying climate with scarcer food options, relied primarily on undergroundstorage organs (such astubers) and food sharing, which facilitated social bonding among both male and female group members. However, unlike what is presumed forH. ergaster and laterHomo, short-statured earlyHomo are generally considered to have been incapable ofendurance running and hunting, and the long andAustralopithecus-like forearm ofH. habilis could indicate earlyHomo were still arboreal to a degree. Also, organisedhunting and gathering is thought to have emerged inH. ergaster. Nonetheless, the proposed food-gathering models to explain large brain growth necessitate increased daily travel distance.[59] It has also been argued thatH. habilis instead had long, modern humanlike legs and was fully capable of effective long distance travel, while still remaining at least partially arboreal.[18]
Largeincisor size inH. habilis compared toAustralopithecus predecessors implies this species relied on incisors more. Thebodies of the mandibles ofH. habilis and other earlyHomo are thicker than those of modern humans and all living apes, more comparable toAustralopithecus. The mandibular body resists torsion from thebite force or chewing, meaning their jaws could produce unusually powerful stresses while eating. The greater molarcusprelief inH. habilis compared toAustralopithecus suggests the former used tools to fracture tough foods (such as pliable plant parts or meat), otherwise the cusps would have been more worn down. Nonetheless, the jaw adaptations for processing mechanically challenging food indicates technological advancement did not greatly affect diet.[35]
H. habilis is associated with theEarly Stone Age Oldowan stone tool industry. Individuals likely used these tools primarily to butcher and skin animals and crush bones, but also sometimes to saw and scrape wood and cut soft plants.Knappers – individuals shaping stones – appear to have carefully selectedlithic cores and have known that certain rocks would break in a specific way when struck hard enough and on the right spot, and they produced several different types, includingchoppers,polyhedrons, and discoids. Nonetheless, specific shapes were likely not thought of in advance, and probably stem from a lack of standardisation in producing such tools as well as the types of raw materials at the knappers' disposal.[7][60] For example,spheroids are common at Olduvai, which features an abundance of large and softquartz andquartzite pieces, whereasKoobi Fora lacks spheroids and provides predominantly hardbasalt lava rocks. Unlike the laterAcheulean culture invented byH. ergaster / H. erectus, Oldowan technology does not require planning and foresight to manufacture, and thus does not indicate high cognition in Oldowan knappers, though it does require a degree of coordination and some knowledge of mechanics. Oldowan tools infrequently exhibitretouching and were probably discarded immediately after use most of the time.[60]
The Oldowan was first reported in 1934, but it was not until the 1960s that it become widely accepted as the earliest culture, dating to 1.8 mya, and as having been manufactured byH. habilis. Since then, more discoveries have placed the origins of material culture substantially backwards in time,[7] with the Oldowan being discovered inLedi-Geraru andGona in Ethiopia dating to 2.6 mya, perhaps associated with the evolution of the genus.[7][61] Australopithecines are also known to have manufactured tools, such as the 3.3 MaLomekwi stone tool industry,[62] and some evidence of butchering from about 3.4 mya.[63] Nonetheless, the comparatively sharp-edged Oldowan culture was a major innovation from australopithecine technology, and it would have allowed different feeding strategies and the ability to process a wider range of foods, which would have been advantageous in the changing climate of the time.[61] It is unclear if the Oldowan was independently invented or if it was the result of hominin experimentation with rocks over hundreds of thousands of years across multiple species.[7]
In 1962, a 366 cm × 427 cm × 30 cm (12 ft × 14 ft × 1 ft) circle made with volcanic rocks was discovered in Olduvai Gorge. At 61–76 cm (2–2.5 ft) intervals, rocks were piled up to 15–23 cm (6–9 in) high. Mary Leakey suggested the rock piles were used to support poles stuck into the ground, possibly to support awindbreak or a rough hut. Some modern-day nomadic tribes build similar low-lying rock walls to build temporary shelters upon, bending upright branches as poles and using grasses or animal hide as a screen.[64] Dating to 1.75 mya, it is attributed to some earlyHomo, and is the oldest-claimed evidence of architecture.[65]
^Stringer, C.B. (1994). "Evolution of early humans". In Jones, S.; Martin, R.; Pilbeam, D. (eds.).The Cambridge Encyclopedia of Human Evolution. Cambridge:Cambridge University Press. p. 242.
^Schrenk, F.; Kullmer, O.; Bromage, T. (2007). "Chapter 9: The Earliest PutativeHomo Fossils". In Henke, W.; Tattersall, I. (eds.).Handbook of Paleoanthropology. pp. 1611–1631.doi:10.1007/978-3-540-33761-4_52.
^abcdeTobias, P. V. (2009). "Homo habilis—A Premature Discovery: Remembered by One of its Founding Fathers, 42 Years Later". In Frederick E. Grine; John G. Fleagle; Richard E. Leakey (eds.).The First Humans – Origin and Early Evolution of the GenusHomo. Vertebrate Paleobiology and Paleoanthropology. Springer, Dordrecht. pp. 7–15.doi:10.1007/978-1-4020-9980-9_2.ISBN978-1-4020-9980-9.
^Wood, B. (1985). "EarlyHomo in Kenya, systematic relationships". In Delson, E. (ed.).Ancestors: The hard evidence. Alan R. Liss.ISBN978-0-8451-0249-7.
^Strait, D.; Grine, F. E.; Fleagle, J. G. (2014). "Analyzing Hominin Phylogeny: Cladistic Approach".Handbook of Paleoanthropology (2nd ed.). Springer. pp. 2005–2006.ISBN978-3-642-39979-4.
^abUngar, P. S.; Grine, F. E. (2006). "Diet in EarlyHomo: A Review of the Evidence and a New Model of Adaptive Versatility".Annual Review of Anthropology.35:208–228.doi:10.1146/annurev.anthro.35.081705.123153.
^Schwartz, G. T. (2012). "Growth, Development, and Life History throughout the Evolution ofHomo".Current Anthropology.53 (6):400–401.doi:10.1086/667591.S2CID84537505.
^Donald C. Johanson; Fidelis T. Masao; Gerald G. Eck; Tim D. White; Robert C. Walter; William H. Kimbel; Berhane Asfaw; Paul Manega; Prosper Ndessokia; Gen Suwa (21 May 1987). "New partial skeleton ofHomo habilis from Olduvai Gorge, Tanzania".Nature.327 (6119):205–209.Bibcode:1987Natur.327..205J.doi:10.1038/327205a0.PMID3106831.S2CID4321698.
^Domínguez-Rodrigo, M.; Cobo-Sánchez, L. (2017). "A spatial analysis of stone tools and fossil bones at FLK Zinj 22 and PTK I (Bed I, Olduvai Gorge, Tanzania) and its bearing on the social organization of early humans".Palaeogeography, Palaeoclimatology, Palaeoecology.488:28–34.Bibcode:2017PPP...488...21D.doi:10.1016/j.palaeo.2017.04.010.
^abNjau, J. K.; Blumenschine, R. J. (2012). "Crocodylian and mammalian carnivore feeding traces on hominid fossils from FLK 22 and FLK NN 3, Plio-Pleistocene, Olduvai Gorge, Tanzania".Journal of Human Evolution.63 (2):408–417.Bibcode:2012JHumE..63..408N.doi:10.1016/j.jhevol.2011.05.008.PMID21937084.
^Aiello, Leslie C.; Dunbar, R. I. M. (1993). "Neocortex Size, Group Size, and the Evolution of Language".Current Anthropology.34 (2): 188.doi:10.1086/204160.S2CID144347664.
^Ungar, Peter (9 February 2012). "Dental Evidence for the Reconstruction of Diet in African EarlyHomo".Current Anthropology.53:S318 –S329.doi:10.1086/666700.S2CID84437780.
^McPherron, Shannon P.; Alemseged, Zeresenay; Marean, Curtis W.; Wynn, Jonathan G.; Reed, Denne; Geraads, Denis; Bobe, Rene; Bearat, Hamdallah A. (2010). "Evidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia".Nature.466 (7308):857–860.Bibcode:2010Natur.466..857M.doi:10.1038/nature09248.PMID20703305.S2CID4356816.
.png)
