''Australopithecus garhi'' is a species of
australopithecine
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 ...
from the
Bouri Formation
The Bouri Formation is a sequence of sedimentary deposits that is the source of australopithecine and Homo (that is, hominin) fossils, artifacts, and bones of large mammals with cut marks from butchery with tools by early hominins. It is locat ...
in the
Afar Region
The Afar Region (; aa, Qafar Rakaakayak; am, አፋር ክልል), formerly known as Region 2, is a regional state in northeastern Ethiopia and the homeland of the Afar people. Its capital is the planned city of Semera, which lies on the pave ...
of Ethiopia 2.6–2.5 million years ago (mya) during the
Early Pleistocene. The first remains were described in 1999 based on several skeletal elements uncovered in the three years preceding. ''A. garhi'' was originally considered to have been a direct ancestor to ''
Homo
''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...
'' and the human line, but is now thought to have been an offshoot. Like other australopithecines, ''A. garhi'' had a brain volume of ; a jaw which jutted out (
prognathism); relatively large
molars
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
and
premolars; adaptations for both walking on two legs (
bipedalism
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...
) and grasping while climbing (
arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...
ity); and it is possible that, though unclear if, males were larger than females (exhibited
sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
). One individual, presumed female based on size, may have been tall.
''A. garhi'' is the first pre-''Homo'' hominin postulated to have manufactured tools—using them in butchering—and may be counted among a growing body of evidence for pre-''Homo'' stone tool industries (the ability to manufacture tools was previously believed to have separated ''Homo'' from predecessors.) ''A. garhi'' possibly produced the
Oldowan
The Oldowan (or Mode I) was a widespread stone tool archaeological industry (style) in prehistory. These early tools were simple, usually made with one or a few flakes chipped off with another stone. Oldowan tools were used during the Lower ...
industry
Industry may refer to:
Economics
* Industry (economics), a generally categorized branch of economic activity
* Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery
* The wider industrial sector ...
which was previously considered to have been invented by the later ''
H. habilis
''Homo habilis'' ("handy man") is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.31 million years ago to 1.65 million years ago (mya). Upon species description in 1964, ''H. habilis'' was highly c ...
'', though this may have instead been produced by contemporary ''Homo''.
Taxonomy
The Ethiopian ''Australopithecus garhi'' was first described in 1999 by palaeoanthropologists
Berhane Asfaw
Berhane Asfaw (Amharic: በርሃነ አስፋው) (born August 22, 1954 in Gondar, Ethiopia) is an Ethiopian paleontologist of Rift Valley Research Service, who co-discovered human skeletal remains at Herto Bouri, Ethiopia later classified as ...
,
Tim D. White,
Owen Lovejoy
Owen Lovejoy (January 6, 1811 – March 25, 1864) was an American lawyer, Congregational minister, abolitionist, and Republican congressman from Illinois. He was also a "conductor" on the Underground Railroad. After his brother Elijah Lo ...
, Bruce Latimer, Scott Simpson, and
Gen Suwa
Gen Suwa (born 1954) is a Japanese paleoanthropologist. He is known for his contributions to the understanding of the evolution of early hominids, including the discovery of a tooth from a hominid that was more than one million years older than the ...
based on fossils discovered in the Hatayae Beds of the
Bouri Formation
The Bouri Formation is a sequence of sedimentary deposits that is the source of australopithecine and Homo (that is, hominin) fossils, artifacts, and bones of large mammals with cut marks from butchery with tools by early hominins. It is locat ...
in
Middle Awash
The Middle Awash is a paleoanthropological research area in the Afar Region along the Awash River in Ethiopia'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 ...
,
Afar Region
The Afar Region (; aa, Qafar Rakaakayak; am, አፋር ክልል), formerly known as Region 2, is a regional state in northeastern Ethiopia and the homeland of the Afar people. Its capital is the planned city of Semera, which lies on the pave ...
, Ethiopia. The first hominin remains were discovered here in 1990—a partial
parietal bone
The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is nam ...
(GAM-VP-1/2), left jawbone (GAM-VP-1/1), and left
humerus (MAT-VP-1/1)—which are unassignable to a specific
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
. The first identifiable ''Australopithecus'' fossils–an adult
ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
(BOU-VP-11/1)–were found on 17 November 1996 by T. Assebework. A partial skeleton (BOU-VP-12/1) was discovered 13 days later by White, comprising a mostly complete left
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...
, right
humerus,
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
, and
ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
, and a partial
fibula
The fibula or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. Its upper extremity i ...
, foot, and jawbone. The
holotype specimen
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
, a partial skull (BOU-VP-12/130), was discovered on 20 November 1997 by Ethiopian palaeoanthropologist
Yohannes Haile-Selassie
Yohannes Haile-Selassie Ambaye (born 23 February 1961) is an Ethiopian paleoanthropologist. An authority on pre-''Homo sapiens'' hominids, he particularly focuses his attention on the East African Rift and Middle Awash valleys.Mangels, John (200 ...
. More skull fragments (BOU-VP-12/87) were recovered south of BOU-VP-12/1. On 17 November 1997, French palaeoanthropologist Alban Defleur discovered a complete mandible (BOU-VP-17/1) about north in the Esa Dibo
locality
Locality may refer to:
* Locality (association), an association of community regeneration organizations in England
* Locality (linguistics)
* Locality (settlement)
* Suburbs and localities (Australia), in which a locality is a geographic subdivis ...
of the formation, and American palaeoanthropologist David DeGusta discovered a humerus (BOU-VP-35/1) north of BOU-VP-17/1. However, BOU-VP-11, -12, and -35 cannot conclusively be attributed to ''A. garhi''.
The remains are dated to about 2.5 million years ago (mya) based on
argon–argon dating
Argon–argon (or 40Ar/39Ar) dating is a radiometric dating method invented to supersede potassiumargon (K/Ar) dating in accuracy. The older method required splitting samples into two for separate potassium and argon measurements, while the newer ...
. When they were discovered, human evolution was obscured due to a paucity of remains from 3 to 2 mya, with the only
hominin
The Hominini form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes the extant genera ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos) and in standard usage excludes the genus ''Gorilla'' (gorillas).
The ...
s from this timespan being identified from South Africa (''
A. africanus'') and
Lake Turkana, Kenya (''
Paranthropus aethiopicus
''Paranthropus aethiopicus'' is an extinct species of robust australopithecine from the Late Pliocene to Early Pleistocene of East Africa about 2.7–2.3 million years ago. However, it is much debated whether or not ''Paranthropus'' is an invali ...
''). Likewise, the classification of
australopithecine
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 ...
s and pre-''
Homo erectus'' hominins has been the subject of much debate. The original describers considered ''A. garhi'' to be a descendant of the earlier ''
A. afarensis'' which inhabited the same region, based mainly on dental similarities. Though they assigned the species to ''
Australopithecus
''Australopithecus'' (, ; ) is a genus of early hominins that existed in Africa during the Late Pliocene and Early Pleistocene. The genus ''Homo'' (which includes modern humans) emerged within ''Australopithecus'', as sister to e.g. ''Austral ...
'', the original describers believed it could represent an ancestor to ''Homo'', which, if the case, would possibly lead to reclassification as ''H. garhi''. Because the characteristics of ''A. garhi'' are unexpected for a human ancestor at this stage, the
specific name, ''garhi'', means "surprise" in the local
Afar language.
In 1999, American palaeoanthropologists David Strait and
Frederick E. Grine
Frederick Edward Grine is an American paleoanthropologist. He is a Professor of anthropology and anatomical sciences at the State University of New York at Stony Brook.
He received his bachelor's degree from Washington & Jefferson College, and his ...
concluded that ''A. garhi'' was instead an offshoot of the human line instead of an ancestor because ''A. garhi'' and ''Homo'' share no
synapomorphies (traits unique to only them).
In 2015, ''Homo'' was recorded from 2.8 mya, much earlier than ''A. garhi''.
Anatomy
Like other australopithecines, ''A. garhi'' had a brain volume of about , a
sagittal crest running along the midline of the skull, and a
prognathic jaw (the jaw jutted out). Relatively, the postcanine teeth, the
molars
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
and
premolars, are massive (
post-canine megadontia
Post-canine megadontia is a relative enlargement of the molars and premolars compared to the size of the incisors and canines. This phenomenon is seen in some early hominid ancestors such as ''Paranthropus aethiopicus.''
Archaeological evidence ...
), similar to or greater than those of other australopithecines and of the large-toothed ''
Paranthropus robustus''.
Like the earlier ''A. afarensis'' from the same region, ''A. garhi'' had a humanlike humerus to femur ratio, and an apelike brachial index (lower to upper arm ratio) as well as curved
phalanges of the hand.
This is generally interpreted as adaptations for both walking on two legs (habitual
bipedalism
Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' ...
) as well as for grasping while climbing in trees (
arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...
ity).
The BOU-VP-35/1 humerus specimen is notably larger than the humerus of the BOU-VP-12/1 specimen, which could potentially indicate size-specific
sexual dimorphism
Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...
with males larger than females to a similar degree to what is postulated in ''A. afarensis'', but it is unclear if this does not represent normal size variation of the same sex as this is based on only two specimens. Nonetheless, on the basis of size, BOU-VP-12/130 is considered male and BOU-VP-17/1 female. Contemporary hominins from Kenya are about the same size as ''A. garhi''.
BOU-VP-17/1 may have been about tall.
[
''Australopithecus'' are thought to have had fast, apelike growth rates, lacking an extended childhood typical of modern humans. However, the legs of ''A. garhi'' are elongated, unlike those of other ''Australopithecus'', and, in humans, elongated limbs develop during the delayed adolescent growth spurt. This could mean that ''A. garhi'', compared to other ''Australopithecus'', either had a slower overall growth rate, or a more rapid leg growth rate.][
]
Palaeoecology
The large teeth of ''Australopithecus'' species have historically been interpreted as having been adaptations for a diet of hard foods, but the durable teeth may instead have only served an important function during leaner times for harder fallback foods. That is, dental anatomy may not accurately portray normal ''Australopithecus'' diet, rather abnormal diet during times of famine.
Though it was not found with any tools, mammalian bones associated with the ''A. garhi'' remains exhibit cut and percussion marks made from stone tools: the left mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
of an alcelaphine bovid
The Bovidae comprise the biological family of cloven-hoofed, ruminant mammals that includes cattle, bison, buffalo, antelopes, and caprines. A member of this family is called a bovid. With 143 extant species and 300 known extinct species, ...
with three successive, unambiguous cut marks presumably made while removing the tongue; a bovid tibia
The tibia (; ), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outside of the tibia); it connects ...
with cut marks, chop marks, and impact scars from a hammerstone
In archaeology, a hammerstone is a hard cobble used to strike off lithic flakes from a lump of tool stone during the process of lithic reduction. The hammerstone is a rather universal stone tool which appeared early in most regions of the wo ...
, possibly inflicted to harvest the bone marrow; and a ''Hipparion
''Hipparion'' (Greek, "pony") is an extinct genus of horse that lived in North America, Asia, Europe, and Africa during the Miocene through Pleistocene ~23 Mya—781,000 years ago. It lived in non-forested, grassy plains, shortgrass prairie or ...
'' (a horse) femur with cut marks consistent with dismemberment and filleting. As to why stone tools were not present, because the Hatayae locality was likely a featureless, grassy lake margin with so few raw materials for making stone tools, it is possible these hominins were creating and carrying tools some ways with them to butchering sites, intending to use them many times before discarding. It was previously believed that only ''Homo
''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...
'' could manufacture tools;[ but it is also possible that the butcherers were not manufacturing tools and simply used naturally sharp rocks.]
At the nearby Gona site, where there is an abundance of raw materials, several Oldowan
The Oldowan (or Mode I) was a widespread stone tool archaeological industry (style) in prehistory. These early tools were simple, usually made with one or a few flakes chipped off with another stone. Oldowan tools were used during the Lower ...
tools (an industry
Industry may refer to:
Economics
* Industry (economics), a generally categorized branch of economic activity
* Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery
* The wider industrial sector ...
previously believed to have been invented by ''H. habilis
''Homo habilis'' ("handy man") is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.31 million years ago to 1.65 million years ago (mya). Upon species description in 1964, ''H. habilis'' was highly c ...
'') were recovered from 1992 to 1994. The tools date to around 2.6–2.5 mya, the oldest evidence of manufacturing at the time, and since ''A. garhi'' was the only species identified in the vicinity at the time, this species was the best candidate for authorship. However, in 2015, the earliest remains of ''Homo'', LD 350-1
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 above the Gurumaha Tuff section of th ...
, were discovered in Ledi-Geraru
Ledi-Geraru is a paleoanthropological research area in Mille district, Afar Region, northeastern Ethiopia, along the Ledi and Geraru rivers (two left tributaries of the Awash, south of the Mille river). It stretches for about 50 km, lo ...
, also in the Afar Region, dating to 2.8–2.75 mya.[ More stone tools were found in 2019 dating to about 2.6 mya in Ledi-Geraru, predating the Gona artifacts, and these may be attributed to ''Homo''; the invention of sharp-edged Oldowan tools could actually be due to specific adaptations characteristic of ''Homo''.] Nonetheless, other australopithecines have been associated with stone tool manufacturing, such as the 2010 discovery of cut marks dating to 3.4 mya attributed to ''A. afarensis'', and the 2015 discovery of the Lomekwi
Lomekwi 3 is the name of an archaeological site in Kenya where ancient stone tools have been discovered dating to 3.3 million years ago, which make them the oldest ever found.
Discovery
In July 2011, a team of archeologists led by Sonia Harma ...
culture from Lake Turkana dating to 3.3 mya possibly attributed to ''Kenyanthropus
''Kenyanthropus'' is a hominin genus identified from the Lomekwi site by Lake Turkana, Kenya, dated to 3.3 to 3.2 million years ago during the Middle Pliocene. It contains one species, ''K. platyops'', but may also include the 2 million year ...
''.
See also
References
External links
Reconstruction
by Viktor Deak
*
*
Human Timeline (Interactive)
– Smithsonian, National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...
(August 2016).
*
{{Taxonbar, from=Q310527
Australopithecus
Pliocene primates
Mammals described in 1997
Fossil taxa described in 1997
Prehistoric Ethiopia
Pliocene mammals of Africa