The Middle Awash is a

paleoanthropological Paleoanthropology or paleo-anthropology is a branch of paleontology and anthropology which seeks to understand the early development of anatomically modern humans, a process known as hominization, through the reconstruction of evolutionary kinship ...

research area in the Afar Region along the Awash River in

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the Er ...

's Afar Depression. It is a unique natural laboratory for the study of human origins and evolution and a number of fossils of the earliest hominins, particularly of the ''

Australopithecines Australopithecina or Hominina is a subtribe in the tribe Hominini. The members of the subtribe are generally ''Australopithecus'' ( cladistically including the genera ''Homo'', ''Paranthropus'', and '' Kenyanthropus''), and it typically includ ...

'', as well as some of the oldest known Olduwan stone artifacts, have been found at the site—all of late

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...

, the

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

times, that is, about 5.6 million years ago (mya) to 2.5 mya. It is broadly thought that the divergence of the lines of the earliest

humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...

(hominins) and of chimpanzees ( hominids) was completed near the beginning of that time range, or sometime between seven and five mya. However, the larger community of scientists provide several estimates for periods of divergence that imply a greater range for this event, ''see'' CHLCA: human-chimpanzee split. A recent find of '' Australopithecus anamensis'' is dated to about 4.2 million years ago, which separates it only 200,000 years from an earlier fossil of the more primitive '' Ardipithecus ramidus'' (at 4.4 million years ago). ''

Australopithecus garhi ''Australopithecus garhi'' is a species of australopithecine from the Bouri Formation in the Afar Region of Ethiopia 2.6–2.5 million years ago (mya) during the Early Pleistocene. The first remains were described in 1999 based on several sk ...

'' fossils are dated as recent as the very early

Pleistocene The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed ...

, or 2.5 mya; fossils of ''

Homo erectus ''Homo erectus'' (; meaning " upright man") is an extinct species of archaic human from the Pleistocene, with its earliest occurrence about 2 million years ago. Several human species, such as ''H. heidelbergensis'' and ''H. antecessor' ...

'' in the Daka member at the site (at 1 mya) and ''

Homo sapiens idaltu Herto Man refers to the 154,000 - 160,000-year-old human remains (''Homo sapiens'') discovered in 1997 from the Upper Herto member of the Bouri Formation in the Afar Triangle, Ethiopia. The discovery of Herto Man was especially significant at ...

'' (at 160 ka ago) are found in the middle and late Pleistocene. And patches of fire-baked

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay part ...

, disputed as evidences of the controlled use of fire, are also found in that later period.

Sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sa ...

s at the site were originally deposited in lakes or rivers, and

carbonate A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonat ...

s found there contain low carbon isotope ratios. This information suggests that the environment of the Middle Awash was wet during the late Miocene, and that this currently arid region was occupied then by

woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...

or grassy woodland habitats. Fossil remains of other

vertebrate Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...

s found with the hominins, including the cane rat, further suggest such an environment. The region was the site of periodic

volcanism Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the Earth#Surface, surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the su ...

, which probably created distinct ecological regions inhabited by different species of vertebrate animals. Important hominin fossils found in the Middle Awash include: * '' Ardipithecus kadabba'' * '' Ardipithecus ramidus'' * '' Australopithecus afarensis'' * ''

'' * '' Australopithecus anamensis'' * ''

'' * ''

'' found at Herto Bouri

Notes

References

* {{Authority control Archaeological sites in Ethiopia Awash River Prehistoric Africa Paleoanthropological sites Archaeology of Eastern Africa

See also

Notes

References