The Middle Awash is a paleoanthropological research area in the northwest corner of Gabi Rasu 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 hominins , particularly of the Australopithecines , as well as some of the oldest known Olduwan stone artifacts , have been found at the site—all of late Miocene , the Pliocene , and the very early Pleistocene 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 (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 .
35-503: 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 fossils are dated as recent as the very early Pleistocene , or 2.5 mya; fossils of Homo erectus in the Daka member at the site (at 1 mya) and Homo sapiens idaltu (at 160 ka ago) are found in
70-492: A human . Based on the limited postcranial evidence available, A. anamensis appears to have been habitually bipedal, although it retained some primitive features of its upper limbs. In 1995, Meave Leakey and her associates, taking note of differences between Australopithecus afarensis and the new finds, assigned them to a new species, A. anamensis , deriving its name from the Turkana word anam , meaning "lake". Although
105-597: A palaeontologist . They have two children, Louise (born 1972) and Samira (born 1974). Louise Leakey continues family traditions by conducting palaeontological research. Leakey initially studied zoology and marine zoology at the University of North Wales . Her first contact with the Leakey family was working for the Tigoni Primate Research Centre while studying for her PhD. At this time,
140-433: A dietary shift was also found, suggesting the consumption of harder foods. This was indicated by thicker enamel in teeth and more intense molar crowns. Australopithecus anamensis is the intermediate species between Ardipithecus ramidus and Australopithecus afarensis and has multiple shared traits with humans and other apes. Fossil studies of the wrist morphology of A. anamensis have suggested knuckle-walking, which
175-481: A narrow upper face with no forehead and a large mid-face with broad zygomatic bones. Before this new discovery, it was widely believed that Australopithecus anamensis and Australopithecus afarensis evolved one right after the other in a single lineage. However, with the discovery of MRD, it suggests that A. afarensis did not result from anagenesis , but that the two hominin species lived side by side for at least 100,000 years. Australopithecus anamensis
210-598: A similar diet to that of the modern gorilla. The microwear patterns are consistent on all Australopithecus anamensis molar fossils regardless of location or time. This shows that their diet largely remained the same no matter what their environment. The earliest dietary isotope evidence in Turkana Basin hominin species comes from the Australopithecus anamensis . This evidence suggests that their diet consisted primarily of C3 resources, possibly however with
245-576: A singular large cusp. Additionally, A. anamensis has a narrow first milk molar that contains a large dominant cusp with minimum surface area, which may have been used for crushing. Meave Leakey Meave G. Leakey (born Meave Epps ; 28 July 1942) is a British palaeoanthropologist . She works at Stony Brook University and is co-ordinator of Plio-Pleistocene research at the Turkana Basin Institute. She studies early hominid evolution and has done extensive field research in
280-831: A small amount of C4 derived resources. Within the next 1.99- to 1.67-Ma time period, at least two distinctive hominin taxa shifted to a higher level of C4 resource consumption. At this point, there is no known cause for this shift in diet. One should recognize that this research does not by itself indicate a plant-based diet, because the isotopes can be ingested by eating animals and insects that fed on C3 and C4 resources. A. anamensis had thick, long, and narrow jaws with their side teeth arranged in parallel lines. The palate, rows of teeth, and other characteristics of A. anamensis dentition suggests that they were omnivores and their diets were composed heavily on fruit, similar to chimpanzees . These characteristics came from Ar. ramidus , who were thought to have preceded A. anamensis . Evidence of
315-402: A somewhat wide jaw joint that was flat from front to back, which resembles a curvature similar to those seen in great apes. Furthermore, the ear canal of A. anamensis fossils are narrow in diameter. The ear canal most resembles that of chimpanzees and is contrasting to the wide ear canals of both later Australopithecus and Homo. The first lower premolar of A. anamensis is characterized by
350-673: Is a hominin species that lived approximately between 4.3 and 3.8 million years ago and is the oldest known Australopithecus species, living during the Plio-Pleistocene era. Nearly one hundred fossil specimens of A. anamensis are known from Kenya and Ethiopia , representing over twenty individuals. The first fossils of A. anamensis discovered, are dated to around 3.8 and 4.2 million years ago and were found in Kanapoi and Allia Bay in Northern Kenya. It
385-576: Is a derived trait shared with other African apes. The A. anamensis hand portrays robust phalanges and metacarpals, and long middle phalanges. These characteristics show that the A. anamensis likely engaged in arboreal living but were largely bipedal, although not in an identical way to Homo . All Australopithecus were bipedal, small-brained, and had large teeth. A. anamensis is often confused with Australopithecus afarensis due to their similar bone structure and their habitation of woodland areas. These similarities include thick tooth enamel, which
SECTION 10
#1732765403853420-449: Is a shared derived trait of all Australopithecus and shared with most Miocene hominoids. Tooth size variability in A. anamensis suggests that there was significant body size variation. In relation to their diet, A. anamensis has similarities with their predecessor Ardipithecus ramidus . A. anamensis sometimes had much larger canines than later Australopithecus species. A. anamensis and A. afarensis have similarities in
455-439: Is suggested that the environment was much wetter. While it is not definitive, it also could have been possible that nut or seed-bearing trees could have been present at Allia Bay, however more research is needed. Studies of the microwear on Australopithecus anamensis molar fossils show a pattern of long striations. This pattern is similar to the microwear on the molars of gorillas; suggesting that Australopithecus anamensis had
490-414: Is usually accepted that A. afarensis emerged within this lineage. However, A. anamensis and A. afarensis appear to have lived side by side for at least some period of time, and it is not fully settled whether the lineage that led to extant humans emerged in A. afarensis , or directly in A. anamensis. Fossil evidence determines that Australopithecus anamensis is the earliest hominin species in
525-415: The A. anamensis population). The skull itself was found by Afar herder Ali Bereino in 2016. Other scientists (e.g. Alemseged, Kimbel, Ward, White) cautioned that one forehead bone fossil, which they viewed as not conclusively A. afarensis , should not be taken as disproving the possibility of anagenesis yet. In August 2019, scientists announced the discovery of MRD-VP-1/1 , a nearly intact skull, for
560-476: The Turkana Basin , but likely co-existed with afarensis towards the end of its existence. A. anamensis and A. afarensis may be treated as a single grouping. Preliminary analysis of the sole upper cranial fossil indicates A. anamensis had a smaller cranial capacity (estimated 365-370 c.c. ) than A. afarensis . The first fossilized specimen of the species, although not recognized as such at
595-400: The Turkana Basin . She has Doctor of Philosophy and Doctor of Science degrees. Leakey's research team at Lake Turkana , Kenya made a discovery in 1999. They found a 3.5-million-year-old skull and partial jaw thought to belong to a new branch of the early human family. She named the find Kenyanthropus platyops ("flat-faced man of Kenya"). Leakey was married to Richard Leakey ,
630-473: The evolutionary tree . The A. anamensis find is dated to about 4.2 million years ago, the Ar. ramidus find to 4.4 million years ago, placing only 200,000 years between the two species and filling in yet another blank in the pre- Australopithecus hominid evolutionary timeline . In 2010 journal articles were published by Yohannes Haile-Selassie and others describing the discovery of around 90 fossil specimens in
665-632: The humerus and the tibia . They both have human-like features and matching sizes. It has also been found that the bodies of A. anamensis are somewhat larger than those of A. afarensis . Based on additional afarensis collections from the Hadar, Ethiopia site, the A. anamensis radius is similar to that of afarensis in the lunate and scaphoid surfaces. Additional findings suggest that A. anamensis have long arms compared to modern humans. Based on fossil evidence, A. anamensis expresses high degrees of sexual dimorphism . Although considered to be
700-417: The 2000s from stratigraphic sequences dating to about 4.1–4.2 million years ago. Specimens have been found between two layers of volcanic ash , dated to 4.17 and 4.12 million years, coincidentally when A. afarensis appears in the fossil record. The fossils (twenty one in total) include upper and lower jaws , cranial fragments, and the upper and lower parts of a leg bone ( tibia ). In addition to this,
735-439: The aforementioned fragment of humerus found in 1965 at the same site at Kanapoi has now been assigned to this species. In 2006, a new A. anamensis find was officially announced, extending the range of A. anamensis into northeast Ethiopia. Specifically, one site known as Asa Issie provided 30 A. anamensis fossils. These new fossils, sampled from a woodland context, include the largest hominid canine tooth yet recovered and
SECTION 20
#1732765403853770-647: The centre was being administered by Louis Leakey . She received her PhD in zoology in 1968. In 2004, she was awarded an honorary D.Sc. from University College , London, for palaeontology. That same year, she received the Golden Plate Award of the American Academy of Achievement . Leakey is currently a Research Professor for the Turkana Basin Institute (affiliated with Stony Brook University ). On 30 April 2013, Leakey
805-454: The cranial capacity is much smaller and the face is very prognathic , both of which indicate that it is earlier than A. afarensis . Known as the MRD cranium, it is that of a male who was at an "advanced developmental age" determined by the worn down post-canine teeth. The teeth show mesiodistal elongation, which differs from A. afarensis . Similar to other australopiths , however, it has
840-407: The earliest Australopithecus femur . The find was in an area known as Middle Awash , home to several other more modern Australopithecus finds and only six miles (9.7 kilometers) away from the discovery site of Ardipithecus ramidus , the most modern species of Ardipithecus yet discovered. Ardipithecus was a more primitive hominid, considered the next known step below Australopithecus on
875-489: The excavation team did not find hips, feet or legs, Meave Leakey believes that Australopithecus anamensis often climbed trees. Tree climbing was one behavior retained by early hominins until the appearance of the first Homo species about 2.5 million years ago. A. anamensis shares many traits with Australopithecus afarensis and may well be its direct predecessor. Fossil records for A. anamensis have been dated to between 4.2 and 3.9 million years ago, with findings in
910-455: The first time, and dated to 3.8 million years ago, of A. anamensis in Ethiopia. The skull itself was found by Afar herder Ali Bereino in 2016. This skull is important in supplementing the evolutionary lineage of hominins . The skull has a unique combination of derived and ancestral characteristics. It was determined that the cranium is older than A. afarensis through analyzing that
945-493: The middle and late Pleistocene. And patches of fire-baked clay , disputed as evidences of the controlled use of fire, are also found in that later period. Sediments at the site were originally deposited in lakes or rivers, and carbonates 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
980-499: The more primitive of the australopiths, A. anamensis had parts of the knee, tibia, and elbow that were different from apes, which indicates bipedalism as the species' form of locomotion. Specifically, the tibia bone of A. anamensis has a more expansive upper end with bone. In addition to the modified body parts that indicate bipedalism, A. anamensis fossils show evidence of tree climbing. Archeology finds indicate that A. anamensis had long forearms, as well as modified features of
1015-450: The same Haile-Selassie team announced the discovery of a nearly intact skull for the first time, and dated to 3.8 mya, of A. anamensis in Ethiopia. This discovery also indicated that an earlier forehead bone fossil from 3.9 mya was A. afarensis and therefore the two species over-lapped and could not be a chronospecies (noting that this does not prevent A. afarensis being descended from A. anamensis , but would be descended from only part of
1050-556: The specimen's age to 4.0–4.5 mya based on faunal correlation data. In 1994, the London-born Kenyan paleoanthropologist Meave Leakey and archaeologist Alan Walker excavated the Allia Bay site and uncovered several additional fragments of the hominid, including one complete lower jaw bone which closely resembles that of a common chimpanzee (Pan troglodytes) but whose teeth bear a greater resemblance to those of
1085-547: The time period 3.6 to 3.8 million years ago (mya), in the Afar area of Ethiopia, filling in the time gap between A. anamensis and Australopithecus afarensis and showing a number of features of both. This supported the idea (proposed for instance by Kimbel et al. in 2006 ) that A. anamensis and A. afarensis were in fact one evolving species (i.e. a chronospecies resulting from anagenesis ), but in August 2019, scientists from
Middle Awash - Misplaced Pages Continue
1120-614: The time, was a single fragment of humerus (arm bone) found in Pliocene strata in the Kanapoi region of West Lake Turkana by a Harvard University research team in 1965. Bryan Patterson and William W. Howells 's initial paper on the bone was published in Science in 1967; their initial analysis suggested an Australopithecus specimen and an age of 2.5 million years. Patterson and colleagues subsequently revised their estimation of
1155-482: The wrist bone. Both the forearms and finger bones of A. anamensis indicate a potential of utilizing the upper limbs as support when operating in trees or on the ground. Forearm bones belonging to A. anamensis have been found to be 265 millimeters to 277 millimeters in length. The curved proximal hand phalanx of A. anamensis in the fossil record that contains strong ridges is indicative of its potential ability to climb. Fossil evidence reveals that A. anamensis had
1190-459: Was found in Kenya, specifically at Allia Bay, East Turkana. Through analysis of stable isotope data, it is believed that their environment had more closed woodland canopies surrounding Lake Turkana than are present today. The greatest density of woodlands at Allia Bay was along the ancestral Omo River. There was believed to be more open savanna in the basin margins or uplands. Similarly at Allia Bay, it
1225-577: Was occupied then by woodland or grassy woodland habitats. Fossil remains of other vertebrates found with the hominins, including the cane rat , further suggest such an environment. The region was the site of periodic volcanism , which probably created distinct ecological regions inhabited by different species of vertebrate animals. Important hominin fossils found in the Middle Awash include: 10°17′N 40°30′E / 10.283°N 40.500°E / 10.283; 40.500 Australopithecus anamensis Australopithecus anamensis
#852147