Australopithecus

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Australopithecus
Australopithecus sediba, head of the holotype (original)

Australopithecus sediba ,
head of the holotype (original)

Temporal occurrence
Pliocene
4.2 to 2 million years
Locations
Systematics
Old World Monkey (Catarrhini)
Human (Hominoidea)
Apes (Hominidae)
Homininae
Hominini
Australopithecus
Scientific name
Australopithecus
Dart , 1925

Australopithecus is anextinct genus knownonly from Africa in the Australopithecina group , which lived around 4 to 2 million years ago. The genus Australopithecus is assigned to the tribe of Hominini , which also includes the genus Homo, including modern humans . According to Richard Leakey , all species, as evidenced by their small brains and all other anatomical features, were "upright monkeys", apart from their posture, most closely comparable to the steppe baboons living today.

Naming

Australopithecus is an artificial word . The name of the genus is derived from Latin australis ("south", because of the location in the South African town of Taung ) and Greek πίθηκος, old Gr. pronounced píthēkos ("monkey"); Australopithecus means "southern monkey". This designation was chosen by Raymond Dart in 1925 . The epithet of the type species, Australopithecus africanus , refers to the continent in which the skull bones of the first fossil of the genus - and so far all other fossils of the genus - were discovered.

Initial description

Holotype of the species and also the type species Australopithecus africanus is known as the Taung child , a fossil skull in the fall of 1924 in the today South Africa belonging village Taung discovered in February 1925 by Raymond Dart scientifically described was.

features

The species of the genus Australopithecus are distinguished from each other and from the ancestors of today's chimpanzees primarily by the differently shaped chewing surfaces of their teeth, the shape of their zygomatic arches and the attachment points of a masticatory muscle (the temporalis muscle ) . Further distinguishing features result u. a. from the structure of the spine, pelvis and hip joints .

Like humans, the dentition does not have an upper jaw - diastema . So there is usually no tooth gap between the lateral incisor and the canine , which in turn indicates that the canines of the lower jaw - unlike, for example in the male non-human primates were not extended dagger-like -.

From the structure and the traces of wear of the dentition it was deduced that Australopithecus anamensis , Australopithecus afarensis , Australopithecus africanus , Australopithecus sediba and the species of the genus Paranthropus mainly fed on vegetable food.

Brain volume and body size

Original of the skull of Mrs. Ples ( Australopithecus africanus )

The brain volume of the Australopithecus species was about 400 to 550 cm 3, a little larger than that of a chimpanzee or bonobo , but smaller than that of the oldest members of the genus Homo , whose brain volume is given as 600 to 800 cm 3 .

The body size of fossil species can only be roughly estimated even from long leg bones found intact; therefore the information on this in the specialist literature varies considerably between approx. 1.00 m and 1.60 m. For Australopithecus africanus , for example, in a review article - with a presumed body weight of 30 to 40 kg - 1.38 m for male and 1.15 m for female specimens are given. This made the australopithecines as big as an upright chimpanzee. It is disputed how pronounced the sexual dimorphism was; It is sometimes argued in the literature that individuals of different sizes may belong to different species that lived in the same area at the same time.

The upright walk

The common characteristic of the genus Australopithecus was the upright gait in older publications . This ability was derived from South African finds ( Australopithecus africanus ), from fossils from Hadar ( Australopithecus afarensis ) and from the approximately 3.5 million year old bipedal footprints from Laetoli .

But in 1991 the Israeli paleoanthropologist Yoel Rak of Tel Aviv University pointed out that Australopithecus afarensis most likely had a "mode of locomotion of its own". More and more paleontological finds have refuted the initial assumption that the early representatives of the hominini lived in open landscapes comparable to modern steppes (“ savannah hypothesis ”). Accompanying finds of the fossil bones consistently point to a habitat that mainly consisted of sparse forests and gallery forests . In this habitat - so the newer interpretation - should the original life of the great apes still have been retained: a frequent stay on trees, especially for sleeping, and only occasionally walk upright on the floor. The view “that the Australopithecines were less human in terms of their locomotion than was initially assumed” has largely prevailed. At the same time, hip bones and hip joints were probably already so well adapted to upright walking that trees could not be climbed as forcefully as today's chimpanzees, for example.

Age

The species of the genus Australopithecus lived - as evidenced by fossil finds that are attributed to Australopithecus - around four to around two million years ago in Africa. From when to when a fossil species existed can usually only be determined approximately. On the one hand, the fossil record is incomplete: there are usually only very few specimen copies for a fossil species. On the other hand, the dating methods indicate a certain age, but with considerable inaccuracy ; this inaccuracy then forms the outer limits for the "from ... to" information for lifetimes. All published age information is therefore provisional, which may also have to be revised after further specimen copies have been found.

From a species of the genus Australopithecus that has not yet been determined with certainty - according to the current state of research this could have been Australopithecus afarensis - the species of the genus Homo emerged through anagenesis ; therefore no “extinction time” can be specified for this genus.

Tool use

The extent to which Australopithecus used tools beyond the level of chimpanzees (cf. tool use in animals ) has not yet been conclusively clarified. Often the use of worked stone tools ( rubble tools ) is even mentioned as a primary criterion to designate certain fossil finds as Homo habilis and not as "Australopithecus habilis" of the genus Australopithecus .

Australopithecus afarensis is around 500,000 years older than the oldest known tools, and no reliable tool finds have been found for Australopithecus africanus either. In contrast, both stone tools of the Oldowan type and bones with worn tips, possibly used for digging or fishing for termites, were discovered in connection with Paranthropus fossils . Since Homo habilis was also found in the same strata , the assignment is uncertain.

Systematics

Hypothesis on the evolution of the australopithecines , as represented by Friedemann Schrenk , for example, based on the current finds

The genus Australopithecus is a paraphyletic taxon , from which, according to current knowledge, the genera Paranthropus and Homo emerged .

The species status is generally recognized today for Australopithecus anamensis , Australopithecus afarensis , Australopithecus africanus , Australopithecus garhi and Australopithecus sediba . The relationship of the species to each other and to the genera Paranthropus and Homo is largely unclear.

However, it is very likely that Australopithecus anamensis and Australopithecus afarensis are sister species following one another as a result of anagenesis . According to this interpretation, the anamensis finds from Lake Turkana (from Kanapoi, age: around 4.1 million years, also from Allia Bay, age: around 3.9 million years) and the afarensis finds from Laetoli (around 3, 6 million years) and Hadar (3.3 million years and younger) successive remnants of populations of a single lineage.

In 2015 it was proposed to revive the species name Australopithecus prometheus, named in 1948 and later evaluated as a synonym of Australopithecus africanus , as the species name of the fossil StW 573 (" Little Foot ").

"Delicate" and "robust" species

From the fossil finds discovered so far by representatives of the hominini from around 2.5 million years ago, two different forms of evolutionary adaptation can be reconstructed, which today are mostly interpreted as a response to climate change and on the one hand to the "robust", on the other hand to the " graceful “australopithecines. This habitat theory of macroevolution was first developed by Elisabeth Vrba .

Southern Africa then became increasingly dry and cool, which is why the forests with their soft fruit and leaf food disappeared. Instead, savannahs spread , which provided a relatively hard food supply (e.g. grasses , seeds , roots ). The so-called "robust" australopithecines - they are now assigned to the genus Paranthropus - specialized in such hard-fiber plants, according to the fossil record, because they developed extremely strong masticatory muscles and extremely enlarged chewing surfaces on the molars; Paranthropus boisei is therefore sometimes referred to as the “nutcracker man”. The "robust" australopithecines died out about 1 million years ago, because after a new climate change towards more moderate temperatures they were probably no longer able to cope with the food competition of other species:

“At the beginning of the colonization of newly created savannah areas, the robust Australopithecines definitely had selection advantages . However, about 1 million years ago in Africa, on the one hand, specialized herbivores among large mammals (e.g. pigs and antelopes ) and, on the other hand, efficient omnivores supported by effective tool use among hominids had established themselves. The resulting food competition led to the extinction of the robust australopithecines at a time when Homo erectus, the genus Homo, had already started its triumphal march to Asia and Europe. "

The earliest fossils assigned to the genus Homo - called Homo rudolfensis and Homo habilis - emerged from those Australopithecus species which paleoanthropologists classify as "delicate" omnivore species; However, it is unclear whether the tribal history ran directly from Australopithecus afarensis to the genus Homo (as some researchers assume) or from Australopithecus afarensis via Australopithecus africanus to Homo (as other researchers suspect). It is at least very likely, however, that the tradition of tool use (the Oldowan culture) arose in the "graceful" omnivore species - as an alternative to the muscular chewing apparatus of the "robust" australopithecines.

The Australopithecus species at a glance

Australopithecine fossil sites in Africa

Some paleoanthropologists also classify the species of the genus Paranthropus as late representatives of Australopithecus :

The assignment of some fossils to the genus Kenyanthropus is also controversial , as these finds are also interpreted by many researchers as a mere variant of the genus Australopithecus .

Furthermore, Ardipithecus ramidus was initially referred to as Australopithecus ramidus by its discoverers in 1994 and only later designated as a species of the newly established genus Ardipithecus .

Finally, Homo rudolfensis is not interpreted by some researchers as the earliest representative of the genus Homo , but as a later representative of the genus Australopithecus and therefore referred to by these researchers as Australopithecus rudolfensis - an assignment problem that is not uncommon with alleged transitional forms .

See also

literature

  • Yves Coppens : Lucy's knee - the prehistoric beauty and the history of paleontology. Munich 2002 (German edition).
  • Göran Burenhult et al .: The first humans. The origins of man up to 10,000 BC. Jahr-Verlag, Hamburg 2000, ISBN 3-8289-0741-5 .
  • Robert Foley: People Before Homo sapiens. Why and how our kind prevailed. Jan Thorbecke Verlag, 2000, ISBN 3-7995-9084-6 .
  • John T. Robinson : Meganthropus , Australopithecines and Hominids. In: American Journal of Physical Anthropology. Volume 11, No. 1, 1953, pp. 1-38, doi: 10.1002 / ajpa.1330110112 .

Web links

Commons : Australopithecus  - collection of images, videos and audio files
Wiktionary: Australopithecus  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ↑ Richard Leakey : The First Traces. About the origin of man. Goldmann, Munich 1999, ISBN 3-442-15031-0 , p. 68.
  2. ^ Raymond A. Dart : Australopithecus africanus: The man-ape of South Africa. In: Nature. Volume 115, 1925, pp. 195-199, full text .
  3. ↑ see also: Greg Laden, Richard Wrangham: The rise of the hominids as an adaptive shift in fallback foods: Plant underground storage organs (USOs) and australopith origins. In: Journal of Human Evolution. Volume 49, No. 4, 2005 pp. 482–498, doi: 10.1016 / j.jhevol.2005.05.007 , full text (PDF; 233 kB) .
  4. ↑ Steve Jones et al .: The Cambridge Encyclopedia of Human Evolution. Cambridge University Press, 1992, p. 236.
  5. ↑ Ulrich Welsch : How the first primates became homo (1): The history of human fossils. Biology in Our Time, 1/2007, p. 47.
  6. ↑ Ulrich Welsch: How the first primates became homo (1): Die Fossilgeschichte des Menschen , p. 46.
  7. ↑ Yoel Rak : Lucy's pelvic anatomy: its role in bipedal gait. Journal of Human Evolution, Volume 20, 1991, pp. 283-290.
  8. ↑ Winfried Henke , Hartmut Rothe : Stammesgeschichte des Menschen. Springer Verlag, 1998, ISBN 3-540-64831-3 .
  9. ↑ Elaine E. Kozma et al .: Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins. In: PNAS. Volume 115, No. 16, 2018, pp. 4134–4139, doi: 10.1073 / pnas.1715120115 , full text (PDF) .
  10. ↑ Gary J. Sawyer, Viktor Deak: The Long Way to Man. Spektrum Akademischer Verlag, Heidelberg 2008, p. 39 ( A. afarensis ), p. 64 ( A. africanus ), p. 73 ( P. robustus )
  11. ↑ Bernard Wood , Terry Harrison : The evolutionary context of the first hominins. In: Nature , Volume 470, 2011, p. 350, doi : 10.1038 / nature09709 .
  12. ^ William H. Kimbel et al .: What Australopithecus anamensis ancestral to A. afarensis? A case of anagenesis in the hominin fossil record. In: Journal of Human Evolution , Volume 51, No. 2, 2006, pp. 134-152, doi : 10.1016 / j.jhevol.2006.02.003 .
  13. ↑ Darryl E. Granger et al .: New cosmogenic burial ages for Sterkfontein Member 2 Australopithecus and Member 5 Oldowan. In: Nature. Volume 522, No. 7554, 2015, pp. 85-88, doi: 10.1038 / nature14268 .
  14. ↑ Friedemann Schrenk : The early days of man. The way to Homo sapiens. CH Beck, 1997, p. 61.
  15. ^ Elisabeth S. Vrba : The Pulse That Produced Us. In: Natural History. 5/1993, pp. 47-51; Full text ( Memento of March 7, 2003 in the Internet Archive )
  16. ↑ Friedemann Schrenk: The early days of people , p. 62.
  17. ↑ Friedemann Schrenk , Timothy Bromage : The hominid corridor of Southeast Africa. In: Spectrum of Science , No. 8/2000, p. 51.
  18. ↑ Lee Berger et al .: Australopithecus sediba: A New Species of Homo-Like Australopith from South Africa. In: Science . Volume 328, 2010, pp. 195-204, doi: 10.1126 / science.1184944 .