Editing Australopithecus afarensis (section)

===Upper limbs===
[[File:Lucy Skeleton.jpg|left|thumb|"[[Lucy (Australopithecus)|Lucy]]" skeleton]]
Like other australopiths, the ''A. afarensis'' skeleton exhibits a mosaic anatomy with some aspects similar to modern humans and others to non-human great apes. The pelvis and leg bones clearly indicate weight-bearing ability, equating to habitual bipedalism, but the upper limbs are reminiscent of orangutans, which would indicate [[arboreal]] locomotion. However, this is much debated, as tree-climbing adaptations could simply be basal traits inherited from the great ape [[last common ancestor]] in the absence of major selective pressures at this stage to adopt a more humanlike arm anatomy.<ref>{{cite journal|first1=J.|last1=Arias-Martorell|first2=J. M.|last2=Potau|first3=G.|last3=Bello-Hellegouarch|first4=A.|last4=Pérez-Pérez|year=2015|title=Like Father, Like Son: Assessment of the Morphological Affinities of A.L. 288–1 (''A. afarensis''), Sts 7 (''A. africanus'') and Omo 119–73–2718 (''Australopithecus'' sp.) through a Three-Dimensional Shape Analysis of the Shoulder Joint|journal=PLOS ONE|volume=10|issue=2|page=e0117408|doi=10.1371/journal.pone.0117408|pmc=4317181|pmid=25651542|bibcode=2015PLoSO..1017408A|doi-access=free}}</ref>

The shoulder joint is somewhat in a shrugging position, closer to the head, like in non-human apes.<ref name=Green2012/> Juvenile modern humans have a somewhat similar configuration, but this changes to the normal human condition with age; such a change does not appear to have occurred in ''A. afarensis'' development. It was once argued that this was simply a byproduct of being a small-bodied species, but the discovery of the similarly sized ''[[H. floresiensis]]'' with a more or less human shoulder configuration and larger ''A. afarensis'' specimens retaining the shrugging shoulders show this to not have been the case. The [[spine of scapula|scapular spine]] (reflecting the strength of the back muscles) is closer to the range of gorillas.<ref name=Green2012>{{Cite journal | last1 = Green | first1 = D. J. | last2 = Alemseged | first2 = Z. | doi = 10.1126/science.1227123 | title = ''Australopithecus afarensis'' Scapular Ontogeny, Function, and the Role of Climbing in Human Evolution | journal = Science | volume = 338 | issue = 6106 | pages = 514–517 | year = 2012 | pmid =  23112331|bibcode = 2012Sci...338..514G | s2cid = 206543814 }}</ref>

The forearm of ''A. afarensis'' is incompletely known, yielding various brachial indexes ([[radius (bone)|radial]] length divided by [[humeral]] length) comparable to non-human great apes at the upper estimate and to modern humans at the lower estimate. The most complete [[ulna]] specimen, AL 438–1, is within the range of modern humans and other African apes. However, the L40-19 ulna is much longer, though well below that exhibited in orangutans and gibbons. The AL 438-1 [[metacarpals]] are proportionally similar to those of modern humans and orangutans.<ref>{{cite journal|first1=M. S. M.|last1=Drapeau|first2=C. V.|last2=Ward|year=2007|title=Forelimb Segment Length Proportions in Extant Hominoids and ''Australopithecus afarensis''|journal=American Journal of Physical Anthropology|volume=132|issue=3|pages=327–343|doi=10.1002/ajpa.20533|pmid=17154362}}</ref> The ''A. afarensis'' hand is quite humanlike, though there are some aspects similar to orangutan hands which would have allowed stronger flexion of the fingers, and it probably could not handle large spherical or cylindrical objects very efficiently. Nonetheless, the hand seems to have been able to have produced a [[precision grip]] necessary in using [[stone tool]]s.<ref>{{cite journal|first=M. W.|last=Marzke|year=1983|title=Joint functions and grips of the ''Australopithecus afarensis'' hand, with special reference to the region of the capitate|journal=Journal of Human Evolution|volume=12|issue=2|pages=197–211|doi=10.1016/S0047-2484(83)80025-6|bibcode=1983JHumE..12..197M }}</ref> However, it is unclear if the hand was capable of producing stone tools.<ref>{{cite journal|first1=M.|last1=Domalain|first2=A.|last2=Bertin|first3=G.|last3=Daver|year=2017|title=Was ''Australopithecus afarensis'' able to make the Lomekwian stone tools? Towards a realistic biomechanical simulation of hand force capability in fossil hominins and new insights on the role of the fifth digit|journal=Comptes Rendus Palevol|volume=16|issue=5–6|pages=572–584|doi=10.1016/j.crpv.2016.09.003|bibcode=2017CRPal..16..572D |doi-access=free}}</ref>