Editing Australopithecus afarensis (section)

{{Short description|Extinct hominid from the Pliocene of East Africa}}
{{Good article}}
{{Speciesbox
| fossil_range = {{nowrap|[[Zanclean]] – [[Piacenzian]]}}<br />{{Fossil range|3.9|2.9}}
| image = Reconstruction of the fossil skeleton of "Lucy" the Australopithecus afarensis.jpg
| image_caption = The partial skeleton AL 288-1 ("[[Lucy (Australopithecus)|Lucy]]")
| genus = Australopithecus
| species = afarensis
| authority = [[Donald Johanson|Johanson]], [[Timothy White (anthropologist)|White]], and [[Yves Coppens|Coppens]], 1978<ref name=Johanson1978>{{cite journal|last1=Johanson|first1=Donald C.|author-link=Donald Johanson|last2=White|first2=Tim D.|author-link2=Timothy White (anthropologist)|last3=Coppens|first3=Yves|author-link3=Yves Coppens|title=A New Species of the Genus ''Australopithecus'' (Primates: Hominidae) from the Pliocene of Eastern Africa|journal=Kirtlandia|date=1978|volume=28|pages=1–14|url=https://www.biodiversitylibrary.org/page/51811016}}</ref>
| synonyms = {{collapsible list|title=Synonyms|
* ''Praeanthropus africanus''<br /><small>(Weinert, 1950)</small>
* ''Australopithecus aethiopicus''<br /><small>Tobias, 1980</small>
* ''Homo aethiopicus''<br /><small>(Tobias, 1980)</small>
* ''Homo antiquus''<br /><small>[[Walter Ferguson|Ferguson]], 1984</small>
* ''Afaranthropus antiquus''<br /><small>([[Walter Ferguson|Ferguson]], 1984)</small>
* ''Homo hadar''<br /><small>Bonde and Westergaard, 2004</small>
* ''[[A. bahrelghazali]]''?<br /><small>[[Michel Brunet (paleontologist)|Brunet]] et al., 1996</small>
* ''[[A. deyiremeda]]''?<br /><small>[[Yohannes Haile-Selassie|Haile-Selassie]] et al., 2015</small>
}}
}}
'''''Australopithecus afarensis''''' is an [[extinct]] [[species]] of [[australopithecine]] which lived from about 3.9–2.9 million years ago (mya) in the [[Pliocene]] of [[East Africa]]. The first [[fossil]]s were discovered in the 1930s, but major fossil finds would not take place until the 1970s. From 1972 to 1977, the International Afar Research Expedition—led by anthropologists [[Maurice Taieb]], [[Donald Johanson]] and [[Yves Coppens]]—unearthed several hundreds of [[hominin]] specimens in [[Hadar, Ethiopia|Hadar]], [[Ethiopia]], the most significant being the exceedingly well-preserved skeleton AL 288-1 ("[[Lucy (Australopithecus)|Lucy]]") and the site [[AL 333]] ("the First Family"). Beginning in 1974, [[Mary Leakey]] led an expedition into [[Laetoli]], [[Tanzania]], and notably recovered [[fossil trackway]]s. In 1978, the species was first [[species description|described]], but this was followed by arguments for splitting the wealth of specimens into different species given the wide range of variation which had been attributed to [[sexual dimorphism]] (normal differences between males and females). ''A. afarensis'' probably descended from ''[[A. anamensis]]'' and is hypothesised to have given rise to ''[[Homo]]'', though the latter is debated.

''A. afarensis'' had a tall face, a delicate brow ridge, and [[prognathism]] (the jaw jutted outwards). The jawbone was quite robust, similar to that of [[gorilla]]s. The living size of ''A. afarensis'' is debated, with arguments for and against marked size differences between males and females. Lucy measured perhaps {{cvt|105|cm|ftin}} in height and {{cvt|25–37|kg}}, but she was rather small for her species. In contrast, a presumed male was estimated at {{cvt|165|cm|ftin}} and {{cvt|45|kg}}. A perceived difference in male and female size may simply be [[sampling bias]]. The leg bones as well as the Laetoli fossil trackways suggest ''A. afarensis'' was a competent [[biped]], though somewhat less efficient at walking and slower at running than humans. The arm and shoulder bones have some similar aspects to those of [[orangutan]]s and gorillas, which has variously been interpreted as either evidence of partial tree-dwelling ([[arboreal]]ity), or [[basal (phylogenetics)|basal]] traits inherited from the [[chimpanzee–human last common ancestor]] with no adaptive functionality.

''A. afarensis'' was probably a [[generalist and specialist species|generalist]] [[omnivore]] of both [[C3 carbon fixation|C<sub>3</sub>]] forest plants and [[C4 carbon fixation|C<sub>4</sub>]] [[Crassulacean acid metabolism|CAM]] savanna plants—and perhaps creatures which ate such plants—and was able to exploit a variety of different food sources. Similarly, ''A. afarensis'' appears to have inhabited a wide range of habitats with no real preference, inhabiting open grasslands or woodlands, shrublands, and lake- or riverside forests. Potential evidence of [[stone tool]] use would indicate meat was also a dietary component. Marked sexual dimorphism in primates typically corresponds to a [[Polygyny in animals|polygynous]] society and low dimorphism to [[Monogamy in animals|monogamy]], but the group dynamics of early hominins is difficult to predict with accuracy. Early hominins may have fallen prey to the large carnivores of the time, such as [[big cat]]s and [[hyena]]s.