LD 350-1 is the earliest known specimen of the genusHomo, dating to 2.8–2.75 million years ago (mya), found in the Ledi-Geraru site in the Afar Region of Ethiopia. The specimen was discovered in silts 10 m (33 ft) above the Gurumaha Tuff section of the site[1][2] 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.[1]
LD 350-1 is an adult left jawbone including the canine, both premolars, and all three molars. In terms of overall size, the specimen is within the range of what is seen in small Australopithecus afarensis specimens, and LD 350-1 seems to be a transitional form between Australopithecus and Homo. However, the specimen's anatomy strongly diverges from australopithecines and more closely aligns with Homo: the mental foramina are not located on a depression, it has a symphyseal keel (a line of bone jutting out at the midline of the jaws), the jawbone maintains a more or less constant depth whereas it is deepest under the premolars in some Australopithecus, and there are several differences regarding the tooth crowns. This specimen confirms that Homo dental and jaw anatomy diverged from those of Australopithecus very early on. LD 350-1, like other archaic humans, seems to have lacked a distinct chin.[1]
Classificationedit
The origin of Homo 2.8–2.5 mya is accompanied by climatic changes, but because other Homo specimens are not known from this time period, it is unclear if this was indeed the causal factor.[1] Because of the strong dental divergence exhibited in LD 350-1, it may be that the initial split was caused by a change in diet.[3] The KNM-ER 5431 specimen (comprising left and right premolars and the first two molars) from Koobi Fora, Kenya, dating to 3–2.7 mya could represent the same species as LD 350-1. The discovery of such an early Homo specimen discredits some past hypotheses on the timing of the Australopithecus/Homo transition, including deriving 2.6 mya from A. garhi. It is unclear if A. afarensis, which is known from the same region until 3 mya, was an ancestor to LD 350-1.[1]
In 2019, the earliest Oldowan stone tools were discovered in Ledi-Geraru dating to 2.6 mya and may have been manufactured by the same species as LD 350-1. The invention of the sharp-edged Oldowan may be tied to unique biological changes in Homo. It is unclear if the Oldowan developed independently or from earlier, simpler australopithecine stone traditions (the only one identified is the Lomekwiindustry). In either case, the transition to sharper tools would have allowed different feeding strategies and the ability to process a wider range of foods than australopithecine technology permitted, which would have been advantageous in the changing climate of the time.[4]
^ abcdeVillmoare, B.; Kimbel, W. H.; Seyoum, C.; et al. (2015). "Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia". Science. 347 (6228): 1352–1355. doi:10.1126/science.aaa1343. PMID 25739410.
^ abDiMaggio, E.; Campisano, C. J.; Rowan, J.; et al. (2015). "Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar, Ethiopia". Science. 347 (6228): 1355–1359. doi:10.1126/science.aaa1415. PMID 25739409.
^ abHublin, J.-J. (2015). "Paleoanthropology: How Old Is the Oldest Human?". Current Biology. 26 (11): 453–455. doi:10.1016/j.cub.2015.04.009. PMID 26035786.
^Braun, D. R.; Aldeias, V.; Archer, W.; et al. (2019). "Earliest known Oldowan artifacts at >2.58 Ma from Ledi-Geraru, Ethiopia, highlight early technological diversity". Proceedings of the National Academy of Sciences. 116 (24): 11, 712–11, 717. doi:10.1073/pnas.1820177116. PMC6575601. PMID 31160451.
November 23, 2023
earliest, known, specimen, genus, homo, dating, million, years, found, ledi, geraru, site, afar, region, ethiopia, specimen, discovered, silts, above, gurumaha, tuff, section, site, ethiopian, palaeoanthropologist, chalachew, seyoum, january, 2013, currently, . LD 350 1 is the earliest known specimen of the genus Homo dating to 2 8 2 75 million years ago mya found in the Ledi Geraru site in the Afar Region of Ethiopia The specimen was discovered in silts 10 m 33 ft above the Gurumaha Tuff section of the site 1 2 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 1 LD 350 1 mandible Contents 1 Description 2 Classification 3 Culture 4 See also 5 ReferencesDescription editLD 350 1 is an adult left jawbone including the canine both premolars and all three molars In terms of overall size the specimen is within the range of what is seen in small Australopithecus afarensis specimens and LD 350 1 seems to be a transitional form between Australopithecus and Homo However the specimen s anatomy strongly diverges from australopithecines and more closely aligns with Homo the mental foramina are not located on a depression it has a symphyseal keel a line of bone jutting out at the midline of the jaws the jawbone maintains a more or less constant depth whereas it is deepest under the premolars in some Australopithecus and there are several differences regarding the tooth crowns This specimen confirms that Homo dental and jaw anatomy diverged from those of Australopithecus very early on LD 350 1 like other archaic humans seems to have lacked a distinct chin 1 Classification editThe origin of Homo 2 8 2 5 mya is accompanied by climatic changes but because other Homo specimens are not known from this time period it is unclear if this was indeed the causal factor 1 Because of the strong dental divergence exhibited in LD 350 1 it may be that the initial split was caused by a change in diet 3 The KNM ER 5431 specimen comprising left and right premolars and the first two molars from Koobi Fora Kenya dating to 3 2 7 mya could represent the same species as LD 350 1 The discovery of such an early Homo specimen discredits some past hypotheses on the timing of the Australopithecus Homo transition including deriving 2 6 mya from A garhi It is unclear if A afarensis which is known from the same region until 3 mya was an ancestor to LD 350 1 1 Culture edit nbsp 2 6 Ma Oldowan tools from Ledi Geraru Afar Region EthiopiaIn 2019 the earliest Oldowan stone tools were discovered in Ledi Geraru dating to 2 6 mya and may have been manufactured by the same species as LD 350 1 The invention of the sharp edged Oldowan may be tied to unique biological changes in Homo It is unclear if the Oldowan developed independently or from earlier simpler australopithecine stone traditions the only one identified is the Lomekwi industry In either case the transition to sharper tools would have allowed different feeding strategies and the ability to process a wider range of foods than australopithecine technology permitted which would have been advantageous in the changing climate of the time 4 LD 350 1 lived in a much drier and more open environment than A afarensis typically inhabited 3 Given the abundance of grazing animals the area was likely similar to modern day African open grasslands such as the Serengeti or the Kalahari but the presence of Deinotherium bozasi a browser may indicate gallery forests and Hippopotamus afarensis crocodiles and fish indicate river and lake systems 2 See also editList of human evolution fossils OH 7References edit a b c d e Villmoare B Kimbel W H Seyoum C et al 2015 Early Homo at 2 8 Ma from Ledi Geraru Afar Ethiopia Science 347 6228 1352 1355 doi 10 1126 science aaa1343 PMID 25739410 a b DiMaggio E Campisano C J Rowan J et al 2015 Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar Ethiopia Science 347 6228 1355 1359 doi 10 1126 science aaa1415 PMID 25739409 a b Hublin J J 2015 Paleoanthropology How Old Is the Oldest Human Current Biology 26 11 453 455 doi 10 1016 j cub 2015 04 009 PMID 26035786 Braun D R Aldeias V Archer W et al 2019 Earliest known Oldowan artifacts at gt 2 58 Ma from Ledi Geraru Ethiopia highlight early technological diversity Proceedings of the National Academy of Sciences 116 24 11 712 11 717 doi 10 1073 pnas 1820177116 PMC 6575601 PMID 31160451 Retrieved from https en wikipedia org w index php title LD 350 1 amp oldid 1154584917, wikipedia, wiki, book, books, library,
