skulls of different hominins

The earliest known hominins were for a long time were thought to come from the genus “Australopithecus” , which first appeared between 3 million and 4 million years ago. But now, after discoveries made in the 1990s and early 2000s, many scientists think the oldest hominins belong to another genus, “Ardipithecus”, that first appeared at least 4 million years ago and may be as old as six million years old. Some even older creatures that have been discovered may be hominins. A genus is a class of animals or plants that usually consist of more than one species.

There are many out there that still believe Australopithecus is the oldest hominin. They don’t regard Ardipithecus as a hominin. There are also some who don’t regard Australopithecus as a hominin either. Australopithecus means "southern ape" a reference to the fact that the first Australopithecus fossils were found in southern Africa. [Sources: Australopithecus, Rick Gore, National Geographic, February 1997; Australopithecus, Donald Johanson, National Geographic, March 1996]

Australopithecus mostly lived between two million and four million years. Some have said the genus may be as old as 7.5 million years. In February 1984 an Australopithecine jawbone with two molars — dated at 4 million years ago by nearby fossils and 5.4-5.6 million years ago by rocks — was found near Lake Baringo, Kenya.

The genus Australopithecus is considered the likely precursor of the genus Homo, to which modern humans belong. Though its cranium is comparable to a chimpanzee's, Australopithecus walked upright, as humans do. This was a surprise to anthropologists when the first Australopithecines were discovered because it had been assumed that big-brain of Homo was preceded by a big-brain ancestor, and having a big brain and walking upright evolved together. [Source: Wikipedia]

Scientists have different theories about which hominins evolved into more developed species and which hominins lead to evolutionary dead ends. Some scientists believed that the “Homo” genus evolved from “Australopithecus afarensis” . Others believe it developed from “Australopithecus afarensis” . “Australopithecus Bosei” and “Australopithecus robustus” are believed to be evolutionary dead ends because they lived at the same time as “Homo” species. The various theories are difficult to prove.

Websites and Resources on Hominins and Human Origins: Smithsonian Human Origins Program humanorigins.si.edu ; Institute of Human Origins iho.asu.edu ; Becoming Human University of Arizona site becominghuman.org ; Hall of Human Origins American Museum of Natural History amnh.org/exhibitions ; The Bradshaw Foundation bradshawfoundation.com ; Britannica Human Evolution britannica.com ; Human Evolution handprint.com ; University of California Museum of Anthropology ucmp.berkeley.edu; John Hawks' Anthropology Weblog johnhawks.net/ ; New Scientist: Human Evolution newscientist.com/article-topic/human-evolution

when different hominins lived

Different Australopithecines and Paranthapus

1) Australopithecus africanus
a) A. africanus (lived about 3.3 million to 2.1 million years ago in southern Africa)
b) A. deyiremeda (lived about 3.5 -3.3 million years ago in northern Ethiopia)
c) A. garhi (lived about 2.5 million years ago in Ethiopia)
d) A. sediba (lived about 2 million years ago in southern Africa)

2) Also called Paranthropus (lived about 2.6 million to 1.1 million years ago)
a) P. aethiopicus (lived about 2.5 million years ago in southern Ethiopia)
b) P. robustus (lived about 2 million to 1.2 million years ago in southern Africa)
c) P. boisei (lived about 2.4 million to 1.4 million years ago in Olduvai Gorge in Tanzania)

3) Also called Praeanthropus
a) A. afarensis (lived about 3.9 million to 2.9 million years ago at several sites in Ethiopia and Kenya)
b) A. anamensis (lived about 4.2 million to 3.9 million years ago at several sites in Ethiopia and Kenya)
c) A. bahrelghazali (lived about 3.6 million years ago in Chad)

skulls of different hominins

Australopithecus afarensis

Australopithecus afarensis is one of the oldest know hominin species. Thought to have been primarily a vegetarian, possibly a scavenger, it lived in dry uplands and around wooded lake shores. Australopithecus afarensis (meaning “southern Ape from Afar”) possessed a combination of ape-like and human-like traits. Slender and small-brained, it had large, prominent teeth and walked upright, but had long, strong arms and curved fingers, making it adept for life in the trees. No direct evidence of tool making has been found but tools dated to the period in which lived have been found near A. afarensis fossil sites.

"Lucy" is the most famous example of Australopithecus afarensis. One of the surprising things about A. afarensis is that it was a surprisingly durable creature, surviving for nearly 900,000 years unchanged, between 3.9 and 3 million years ago. In contrast modern man has only been around for 100,000 to 200,000 years and Neanderthals existed for about 300,000 years. A. afarensis is believed to have evolved into other Australopithecus species which eventually died out. Some scientists believe it evolved into other hominin species after a long period with a dryer, cooler climate. These hominins in turn developed into “ Homo” species. [Source: John Noble Wilford, New York Times]

Geologic Age About 3.9 million to 3 million years. Size: males: 1.5 meters (4 feet 11 inches), 45 kilograms (99 pounds). females: 1.1 meters (3 feet 5 inches) tall, 29 kilograms (64 pounds). Males are about the same size as pygmy men in Central Africa. Brain Size: 400 to 500 cubic centimeters. One third the size of a human brain (1,350 cubic centimeters) and about the same size as a chimp brain (390 cubic centimeters). Perhaps same intelligence of an ape. Linkage to Modern Man: Skeletal features indicate she was on the line that lead to the human genus, Homo. Nickname: Lucy.

Discovery Sites: The fossils of more than 300 A. afarensis individuals have been found so researchers know quite a lot about Lucy and her relatives.Lucy was discovered near Hadar, Ethiopia. The skeleton is housed at the National Museum of Ethiopia in Addis Ababa. Remains of 60 “A afarenis” individuals have been discovered at Laetoli, Tanzania. Remains have also been found in the Aramis and Omo areas in Ethiopia and Lake Turkana in Kenya.

Australopithecus Africanus

“Australopithecus africanus” was the first discovered Australopithecus species. Size: Smaller than other Australopithecus species. males: 1.7 meters (4 feet 6 inches), 41 kilograms (90 pounds); females: 1.14 meters (3 feet 9 inches), 30 kilograms (66 pounds). Fragments suggest heights up to five feet. Not much larger than Lucy. Brain Size: 370 to 428 cubic centimeters. Nickname: Taung Child.

Australopithecus africanus is the oldest-known Australopithecus species in southern Africa. The 1.2-meter-tall hominin had long arms for climbing trees and lived in the region when the area of southern Africa that it lived was partly forested. As the climate became drier, the forests gave way to more open grasslands, and new hominids evolved.

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Australopithecus anemensis
Discovery Sites: In 1924 in Taung, South Africa (See Taung Child Below). In 1947 in Sterkfontein Cave, South Africa by R. Broom and J.T. Robinson. About half a skull is housed in the Transvaal Museum, Pretoria. Remains of other “ A. africanus” have been found in Sterkfontein and other South African caves. Sterkfontein produced the world’s oldest known complete Australopithecus skeleton.

Geologic Age 3.3 million to 2.1 million years, possibly 4 million years old. Coming up with accurate dates for “A. africanus” is difficult because there is no volcanic ash in the caves where they were discovered. Less accurate paleomagnetic dating techniques — based on the reversal of the polarity of the earth's magnetic fields at irregular intervals — has come up a date of three million years. [Source: Kenneth Weaver, National Geographic, November 1985 [┹]

In 2003, bones of “ A. africanus” found in Sterkfontein were dated to almost 4 million years ago using a sophisticated dating technique that measures the amounts of isotopes of aluminum and beryllium in materials found around the fossil. Is. If the dates hold up “ A. africanus” would be as old as some of the oldest Australopithecus species found in Ethiopia and Kenya.

Australopithecus anemensis

”Australopithecus anemensis” is the oldest known member of the Australopithecus genus. “Anamnesis” means "of the lake." The early hominin had a jaw that resembled a chimpanzee but a shinbone that suggested it walked upright on two feet. A. Anemensis is among the first known creature with an upright human-like walk. The top of the shinbone (tibia) is thick enough to support the extra weight for walking and the knob at the top of the bone is concave (as opposed to convex in apes), anchoring a more stable knee joint needed for balance. The Ardipithecus genus were also walkers. They are older than “A. Anemensis”. See Ardipithecus (Ardi). Describing the significance of the shinbone, South African paleontologist Lee Berger told Time, "there probably isn't another bone more linked with balance and walking, and this one is absolutely remarkable. It's morphologically very advanced — surprisingly human-like."

Geologic Age About 4.2 million to 3.9 million years. Size: Male: 1.56 meters (5 feet 1 inch), 51 kilograms (112 pounds). females: 1.3 meters (4 feet 3 inches, 33 kilogram (73 pounds.) Linkage to Modern Man: Strong evidence it walked upright. Discovery Sites:
In 1995, researchers found several partial jaws, isolated teeth and limb bones in Kenya, dated between 4.2 million and 3.9 million years old, and assigned them to a brand new species: Australopithecus anamensis. A number of additional specimens were then found in Ethiopia, thought to belong to the same species.

Skull Features: Similar in some ways to the Australopithecus species that followed but distinctly ape-like in other ways. The teeth are vaguely human-looking teeth but the jaw has an apelike mandible. Body Features: Joint surfaces and the strength on the lower leg bone (tibia) indicate a bipedal gate. Long ape-like arms. There is little difference between Australopithecus afarensis and Australopithecus anemensis

Australopithecus anemensis was named “anamnesis” ("of the lake" in the local language) because it was found near Lake Turkana. A 4.1 million-year-old jawbone and 3.5 million-year-old arm bone were found by Dr. Meave Leakey at Kanapoi, near Lake Turkana, and Allia Bay around Lake Turkana in 1996. Leakey's Hominin Gang found 21 bone specimens between 3.9 million and 4.2 million years old. Meave Leaky is the wife of Richard Leakey and daughter in law of Louis and Mary Leakey. Fossils found with “A. anamnesis” indicate that the hominin lived in forested areas, which means that it learned to walk in a place with trees not the open savannah. The teeth are covered in thick enamel which means that diet probably included nut and hard fruit.

3.8-million-Year-Old Australopithecus Anamensis Cranium

Australopithecus anemensis jawbone

In August 2019, researchers announced that they had discovered a "remarkably complete" Australopithecus anamensis cranium (skull without the lower jaw) dating back 3.8 million years in Ethiopia. The fossil, known as MRD-VP-1/1, or simply MRD. was found in February 2016 in Miro Dora at the Woranso-Mille paleontological site in the Afar region in northern Ethiopia, and paleoanthropologists and geologists have been conducting an extensive analysis on it ever since, according to a news release from the Cleveland Museum of Natural History. The researchers published their findings in two papers in August 2019 in the scientific journal Nature. Although more than 100 specimens of A. anamensis have been found in Ethiopia and Kenya, most are isolated teeth and jaw fragments. MRD is the most complete hominin cranium in the fossil record older than three million years ever discovered. [Source: Jarrett A. Lobell, Archaeology magazine, November-December 2019]

ABC News reported: “The Fist-size cranium shared some features with its descendant species as well as with species that are older and and more primitive, such as Ardipithecus and Sahelanthropus, according to the release. The most important conclusion scientists have made is that Australopithecus anamensis coexisted for at least 100,000 years with its descendant species, Australopithecus afarensis, debunking the previous theory that evolution was simply linear over time. “The finding of the skull has allowed scientists to study the morphology of Australopithecus anamensis for the first time. The hominin has a "mix of primitive and derived facial and cranial" or "ape-like" features, Haile-Selassie said. Previously, glimpses of Australopithecus anamensis were only seen through fragments of teeth and jaw [Source: Julia Jacobo, ABC News, August 29, 2019] .

The skull was found in the sandy deposits of a delta where a river entered a lake, according to the release. The first piece of the skull found was the upper jaw, which was exposed on the surface. Scientists found the rest of the cranium after further examining the area. Cleveland Museum of Natural History Curator and Case Western Reserve University Adjunct Professor Dr. Yohannes Haile-Selassie, who led the team of researchers, described the finding as "a eureka moment come true." Early human fossils from between 4.1 million and 3.6 million years ago are "extremely rare," according to the release. Researchers dated minerals in the layers of volcanic rocks nearby to determine the age of the fossil, combining field observations with analysis of microscopic biological remains to reconstruct the landscape, vegetation and hydrology where the human ancestor died, according to the release. Volcanic layers that blanketed the land surface and lake floor allowed the researchers to map out the landscape and how it changed over time, said Beverly Saylor, professor of stratigraphy and sedimentology at Case Western Reserve University, in a statement. The large lake region where the specimen lived was likely dry. Since beginning their field research at the Woranso-Mille site in 2004, researchers have collected more than 12,600 fossil specimens representing about 85 species of mammals, according to the release.

Hester Hanegraef wrote: “The primitive features of A.anamensis have led to the widespread view that this species is the ancestor of Australopithecus afarensis, However, the MRD cranium was intact enough to allow scientists to analyse for the first time the complete face and braincase, and examine parts of the cranium that were still missing in the fossil record of A. anamensis. The authors discovered several new morphological features in the MRD cranium that are conventionally considered to be characteristic of younger species on the human lineage. The depth of the palate, for example, exceeds that of all known A. anamensis and A. afarensis specimens, and even is among the deepest palates of later Australopithecus species. This challenges the long and widely-held view that Lucy’s species evolved gradually from A. anamensis without branching of the evolutionary line — a process known as anagenesis. [Source: Hester Hanegraef, PhD Candidate of Anthropology, Natural History Museum, The Conversation, September 4, 2019]

Since these modern features were already present in the older species, the most likely scenario is that Lucy’s species formed by evolutionary divergence from A. anamensis — a process known as cladogenesis. It is not known though exactly when A. afarensis diverged. Further evidence for cladogenesis comes from a 3.9 million years old frontal bone (part of the forehead) from Ethiopia, discovered in 1981. Its shape is different from MRD which suggests this fossil probably belongs to A. afarensis.

Australopithecus Deyiremeda

Australopithecus deyiremeda lived about 3.3 to 3.5 million years ago. Parts of jaws and teeth from this species were found in the Woranso-Mille area of the Afar region of Ethiopia — near where Lucy, the famed Australopithecus afarensis, was discovered in 1974. Australopithecus deyiremeda may have coexisted with Lucy’s species, but appears to have been adapted to take advantage of tougher plants and grasses than A. afarensis. [Source: Samir S. Patel, Archaeology magazine, September-October 2015]

The discovery of Australopithecus deyiremeda was described in the May 28, 2015 issue of the journal Nature. “Lucy’s species lived from 2.9 million years ago to 3.8 million years ago, overlapping in time with the new species Australopithecus deyiremeda. The new species is the most conclusive evidence for the contemporaneous presence of more than one closely related early human ancestor species prior to 3 million years ago. The species name “deyiremeda” (day-ihreme-dah) means “close relative” in the language spoken by the Afar people. [Source: Cleveland Museum of Natural History and Leakey Foundation, May 28, 2015 \^^/]

“Australopithecus deyiremeda differs from Lucy’s species in terms of the shape and size of its thick-enameled teeth and the robust architecture of its lower jaws. The anterior teeth are also relatively small indicating that it probably had a different diet. “The new species is yet another confirmation that Lucy’s species, Australopithecus afarensis, was not the only potential human ancestor species that roamed in what is now the Afar region of Ethiopia during the middle Pliocene,” said lead author and Woranso-Mille project team leader Dr. Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History.” The researchers say the fossils also show evidence of tooth and jaw traits that were thought to have appeared much later in the human family tree. “Current fossil evidence from the Woranso-Mille study area clearly shows that there were at least two, if not three, early human species living at the same time and in close geographic proximity.”“The age of the new fossils is very well constrained by the regional geology, radiometric dating, and new paleomagnetic data,” said co-author Dr. Beverly Saylor of Case Western Reserve University. The combined evidence from radiometric, paleomagnetic, and depositional rate analyses yields estimated minimum and maximum ages of 3.3 and 3.5 million years.” \^^/

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Discovery of Australopithecus Deyiremeda

Cleveland Museum of Natural History and Leakey Foundation reported: “The holotype (type specimen) of Australopithecus deyiremeda is an upper jaw with teeth discovered on March 4, 2011, on top of a silty clay surface at one of the Burtele localities. The paratype lower jaws were also surface discoveries found on March 4 and 5, 2011, at the same locality as the holotype and another nearby locality called Waytaleyta. The holotype upper jaw was found in one piece (except for one of the teeth which was found nearby), whereas the mandible was recovered in two halves that were found about two meters apart from each other. The other mandible was found about 2 kilometers east of where the Burtele specimens were found. [Source: Cleveland Museum of Natural History and Leakey Foundation, May 28, 2015 \^^/]

“The fossil specimens were found in the Woranso-Mille Paleontological Project study area located in the central Afar region of Ethiopia about 325 miles (520 kilometers) northeast of the capital Addis Ababa and 22 miles (35 kilometers) north of Hadar (“Lucy’s” site). Burtele and Waytaleyta are local names for the areas where the holotype and paratypes were found and they are located in the Mille district, Zone 1 of the Afar Regional State. \^^/

The Woranso-Mille Paleontological project conducts field and laboratory work in Ethiopia every year. This multidisciplinary project is led by Dr. Yohannes Haile-Selassie of The Cleveland Museum of Natural History. Additional co-authors of this research include: Dr. Luis Gibert of University of Barcelona (Spain), Dr. Stephanie Melillo of the Max Planck Institute (Leipzig, Germany), Dr. Timothy M. Ryan of Pennsylvania State University, Dr. Mulugeta Alene of Addis Ababa University (Ethiopia), Drs. Alan Deino and Gary Scott of the Berkeley Geochronology Center, Dr. Naomi E. Levin of Johns Hopkins University, and Dr. Beverly Z. Saylor of Case Western Reserve University. Graduate and undergraduate students from Ethiopia and the United States of America also participated in the field and laboratory activities of the project.”

Several Australopithecine Species Lived at the Same Time

Hester Hanegraef wrote: A. anamensis existing from 4.2 million to 3.8 million years ago, and A. afarensis from 3.9 million to 3 million years ago. This would imply that both species were overlapping for at least 100,000 years, making it impossible for A. afarensis to have evolved gradually from one single ancestral group. In fact, it is becoming increasingly obvious that most species on our evolutionary lineage likely evolved by branching off from existing groups.

The new discovery also challenges the idea of Lucy’s species being the ancestor of all later Australopithecus hominins, which eventually led to humans. A vertically straight and steeply rising curvature of the cheekbone has traditionally been considered to be a relatively modern feature. It was present in Australopithecus africanus (3.7 million -2.1 million years ago from southern Africa, considered by some to be a direct ancestor of the Homo lineage) and in Paranthropus (2.7 million -1.2 million years ago from southern and eastern Africa, not directly on our evolutionary line). The opposite condition — a low and arched cheekbone — is considered to be primitive, and is shared among A. afarensis, Ardipithecus ramidus (4.3 million -4.5 million years ago from Ethiopia, a more ape-like primitive hominin) and African apes. The crest of the MRD cranium, which is surprisingly modern, now challenges this view. It further opens up the possibility that the longstanding idea of A. afarensis as the ancestor of all later Australopithecus groups might have been wrong, and that instead A. anamensis is the ancestor to these younger species. Which early hominin is the direct ancestor of humans still remains an unanswered question.

Australopithecus sites

“Clearly this latest discovery has given new insights into our evolutionary past, but also increased the complexity of the relationships between early hominins. The mid Pliocene (5.3 million -2.6 million years ago) has become crowded with multiple, contemporary and geographically widespread species. Clarifying the relationships between these species, confidently characterising their morphology, and deciphering the complex and intricate story about hominin evolution is not a simple task. Specimens at each new site capture a different point along the evolutionary trajectory, but it is not easy to convert these findings into stable and reliable branches on an evolutionary tree.

Australopithecus deyiremeda also confirms Several Australopithecine species lived at the same time. Pete Spotts wrote in Christian Science Monitor: “New fossils from Ethiopia are providing fresh evidence that some 3 million to 4 million years ago, ancestors to modern humans may have been more diverse than previously thought. Lucy and her species were not the only Australopithecines on the block. Over the years, researchers have reported uncovering two additional species from this period. This latest discovery holds up, it would bring to four the number of known Australopithecus species living within this million-year span. These species range from Ethiopia to Chad. [Source: Pete Spotts, Christian Science Monitor, May 27, 2015]

“A. deyiremeda's remains were found at a site in Ethiopia's Afar region known as Woranso-Mille, about 22 miles north of another site rich in A. afarensis fossils – pointing to the possibility that the two species roamed the same general region at about the same time. With several Australopithecus species living in eastern and central Africa in the same general period, "we're looking at hominins who are potential candidates as human ancestors," says Henry Bunn, a paleoanthropologist at the University of Wisconsin at Madison. During this period, known as the middle Pliocene, the climate was getting cooler and drier. Vegetation and food resources were changing.

According to the Cleveland Museum of Natural History and Leakey Foundation: “Scientists have long argued that there was only one pre-human species at any given time between 3 and 4 million years ago, subsequently giving rise to another new species through time. This was what the fossil record appeared to indicate until the end of the 20th century. However, the naming of Australopithecus bahrelghazali from Chad and Kenyanthropus platyops from Kenya, both from the same time period as Lucy’s species, challenged this long-held idea.

Australopithecus Bahrelghazali

Australopithecus Bahrelghazali partial jawbone

The partial jawbone of a species called Australopithecus bahrelghazali was found in the mid-1990s in Chad. The early hominin lived 3.5 million to 3 million years ago 1,500 miles west of the Great Rift Valley, the region where most Australopithecus bones have been found. Pollen studies have shown they lived in forests of juniper and olive trees.

The University of Oxford reported: “Researchers involved in a new study led by Oxford University have found that between three million and 3.5 million years ago, the diet of our very early ancestors in central Africa is likely to have consisted mainly of tropical grasses and sedges. The findings are published in the early online edition of Proceedings of the National Academy of Sciences. [Source: University of Oxford, December 14, 2012]

“An international research team extracted information from the fossilised teeth of three Australopithecus bahrelghazali individuals — the first early hominins excavated at two sites in Chad. Professor Julia Lee-Thorp from Oxford University with researchers from Chad, France and the US analysed the carbon isotope ratios in the teeth and found the signature of a diet rich in foods derived from C4 plants.

“Professor Lee-Thorp, a specialist in isotopic analyses of fossil tooth enamel, from the Research Laboratory for Archaeology and the History of Art, said: “We found evidence suggesting that early hominins, in central Africa at least, ate a diet mainly composed of tropical grasses and sedges. No African great apes, including chimpanzees, eat this type of food despite the fact it grows in abundance in tropical and subtropical regions. The only notable exception is the savannah baboon which still forages for these types of plants today. We were surprised to discover that early hominins appear to have consumed more than even the baboons.”

“The research paper suggests this discovery demonstrates how early hominins experienced a shift in their diet relatively early, at least in Central Africa. The finding is significant in signalling how early humans were able to survive in open landscapes with few trees, rather than sticking only to types of terrain containing many trees. This allowed them to move out of the earliest ancestral forests or denser woodlands, and occupy and exploit new environments much farther afield, says the study.

“The fossils of the three individuals, ranging between three million and 3.5 million years old, originate from two sites in the Djurab desert. Today this is a dry, hyper-arid environment near the ancient Bahr el Ghazal channel which links the southern and northern Lake Chad sub-basins. However, in their paper the authors observe that at the time when Australopithecus bahrelghazali roamed, the area would have had reeds and sedges growing around a network of shallow lakes, with floodplains and wooded grasslands beyond.

“Previously, it was widely believed that early human ancestors acquired tougher tooth enamel, large grinding teeth and powerful muscles so they could eat foods like hard nuts and seeds. This research finding suggests that the diet of early hominins diverged from that of the standard great ape at a much earlier stage. The authors argue that it is unlikely that the hominins would have eaten the leaves of the tropical grasses as they would have been too abrasive and tough to break down and digest. Instead, they suggest that these early hominins may have relied on the roots, corms and bulbs at the base of the plant.

“Professor Lee-Thorp said: “Based on our carbon isotope data we can’t exclude the possibility that the hominins’ diets may have included animals that in turn ate the tropical grasses. But as neither humans nor other primates have diets rich in animal food, and of course the hominins are not equipped as carnivores are with sharp teeth, we can assume that they ate the tropical grasses and the sedges directly.”“

Australopithecus aethiopicus

Paranthropus boisei
Australopithecus aethiopicus: Geologic Age: 2.7 million to 2.3 million years. Size: Significantly larger than other Australopithecus species. About 1.5 meters (five feet) tall. Brain Size: About the same as robustus (See Below). Discovery Sites: Omo region in Ethiopia and Lake Turkana in northern Kenya.

Skull Features: massive chewing muscles anchored to prominent bony crest along the top of the skull. Linkage to Modern Man: May be an ancestor of Robustus and boisei or may be different subspecies of a single, variable species. Believed to be an evolutionary dead end. Many scientists regard Australopithecus aethiopicus as a member of the Australopithecus boisei species.

According to the Smithsonian: “Paranthropus aethiopicus is still much of a mystery to paleoanthropologists, as very few remains of this species have been found. The discovery of the 2.5 million year old ’Black Skull’ in 1985 helped define this species as the earliest known robust australopithecine. P. aethiopicus has a strongly protruding face, large megadont teeth, a powerful jaw, and a well-developed sagittal crest on top of skull, indicating huge chewing muscles, with a strong emphasis on the muscles that connected toward the back of the crest and created strong chewing forces on the front teeth.[Source: Smithsonian Human Origins /==]

“Paranthropus aethiopicus was originally proposed in 1967 by a team of French paleontologists to describe a toothless partial mandible (Omo 18) that was thought to differ enough from the mandibles of the early human species known at that time. This naming of a new species was generally dismissed; many paleoanthropologists thought it premature to name a new species on the basis of a single incomplete mandible. In 1985, when Alan Walker and Richard Leakey discovered the famous "Black Skull" west of Lake Turkana in Kenya, the classification reemerged. With its mixture of derived and primitive traits, KNM-WT 17000 validated, in the eyes of many scientists, the recognition of a new "robust" australopithecine species dating to at least 2.5 million years ago in eastern Africa. /==\

“Many features of the skull are quite similar to Australopithecus afarensis, and P. aethiopicus may be a descendent of this species. It is most likely the ancestor of the robust australopithecine species found later in Eastern Africa, Paranthropus boisei. The dark color comes from minerals in the soil that were absorbed by the skull as it fossilized. The front teeth fell out and the others were broken off after the individual died. This is the only known adult skull of this species, which is considered a direct ancestor of Paranthropus boisei.” /==\

Australopithecus garhi

Australopithecus garhi

In April 2000, a team lead by Ethiopian Berhane Asfaw and Tim White of Berkeley announced in Science they discovered a new Australopithecus species, Australopithecus garhi, at the site of Bouri, Middle Awash in the Afar desert of Ethiopia. "Garhi" means surprise in the local language. Dated to around 2.5 million years ago , a crucial period when the early homo species were developing, the fossils consisted of skull and jaw fragments and teeth that showed a remarkable collection of primitive and advanced features.

Australopithecus garhi had protruding facial features and long arms like a chimpanzee; large teeth, three times the size of those on modern humans; and a brain one third the size of modern human. Its legs were long and human-like. A short distance away scientists found stone tools believed to have used by Australopithecus garhi. See First Hominid Tools.

According to the Smithsonian: “This species is not well documented; it is defined on the basis of one fossil cranium and four other skull fragments, although a partial skeleton found nearby, from about the same layer, is usually included as part of the Australopithecus garhi sample. The associated fragmentary skeleton indicates a longer femur (compared to other Australopithecus specimens, like ‘Lucy’) even though long, powerful arms were maintained. This suggests a change toward longer strides during bipedal walking. [Source: Smithsonian Human Origins]/==\

“The human fossil record is poorly known between 3 million and 2 million years ago, which makes the finds from the site of Bouri, Middle Awash Ethiopia, particularly important. First in 1990 and then from 1996 to 1998, a research team led by Ethiopian paleoanthropologist Berhane Asfaw and American paleoanthropologist Tim White found the partial skull (BOU-VP-12/130) and other skeletal remains of an early humans dated to around 2.5 million years old. In 1997, the team named the new species Australopithecus garhi; the word ‘garhi’ means ‘surprise’ in the Afar language. /==\

“Fossils of Australopithecus garhi are associated with some of the oldest known stone tools, along with animal bones that were cut and broken open with stone tools. It is possible, then, that this species was among the first to make the transition to stone toolmaking and to eating meat and bone marrow from large animals. Some scientists claim that the large molar teeth show that Australopithecus garhi is related to Paranthropus aethiopicus; however, the combination of features of the face, braincase, and teeth are unlike Paranthropus. The scientists who originally reported the finds think that Au. garhi may represent an ancestor of the genus Homo The skull has a curious mixture of Homo-like cranial features, an Australopithecus-like brain size, and large Paranthropus-sized teeth.” /==\

Early Hominin Tools: from Australopithecus garhi?

One of the oldest known hominid tools is a 2.6 million-year-old flaked scraping tool found in the Gona region of Ethiopia by a team lead by Sileshi Semaw, an Ethiopian archaeologist now at Indiana University. It is not known who used the tools. Scientists believed it was Australopithecus garhi.

The tools were probably used to break open bones and scrape out the marrow and perhaps to cut meat off the bones. Before this no tools had been linked with australopithecines before. Leg bone of other animals found near the tools had cut and chip marks and signs of hammering.

In 2003, Semaw's team found 2.6 million-year-old tools among bone fragments in the Gona area. Believed to have been used to cut up meat, the tools, scientists say, shed some light on which came first tools or better diets. Semaw told the New York Times, “I believe the stone tools came first and the larger brain came later with a more substantial meat diet."

An antelope jaw with cut marks, indicating its tongue was sliced out with a sharp stone flake was found on the Bouri Peninsuala in Lake Yardi in Ethiopia. The bones, dated to 2.5 million years ago, suggest the toolmakers used tools to scavenge meat and marrow from large animals. Curiously though no actual tools were found at the site. The discovery nearby of Australopithecus garhi bones indicate it again was the most likely the tool maker.

Australopithecus Sebida

Australopithecus sediba

In August 2008, two partial skeletons were unearthed in a cave at the Malapa site 40 kilometers from Johannesburg in South Africa and were dated to be between 1.78 million and 1.95 million years old. After careful study it was determined that the bones belonged to a new species — “Australopithecus sediba” . The skeletons were of a young male and adult female. They were upright-walking Australopithecus but had many physical traits of the earliest known homo species.

Lee Berger, of the University of Witwatersrnad in Johannesburg, who lead the team that found the fossils, called the discovery “unprecedented.” He told Reuters, “I am struck by the exceptional nature of something right on our doorstep...there are more hominin fossils than I have ever discovered in my career. When we found it, we imagined that we were looking at new species.”

Australopithecus sediba had long arms like an ape, short powerful hands, a very advanced pelvis and long legs capable of striding and perhaps running like a human. The female was 1.27 meters tall. The male was about the size but it is assumed it would grow bigger. The brain size of the young male was between 420 and 450 cubic centimeters, considerably smaller than a modern human brain, which is between 1,200 and 1,600 cubic centimeters. The remains of saber-toothed cats, brown hyenas, wild dog, antelopes and a horse were also found in the cave

Burtele Foot: From Yet Another Australopithecus Species?

In March 2012, scientists wrote in the journal Nature that they had found a 3.4 million-year-old fossilized foot in Ethiopia from a hominin found that was not Australopithecus afarensis, Lucy’s species. Catharine Paddock wrote in Medical News Today: “The fossil of the partial foot was found in 3.4-million-year-old rocks at Woranso-Mille in the Afar region of Ethiopia, where lead author Dr Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History in the US, led the field research. “Bones of Australopithecus afarensis, have also been found in the area, which is known locally as Burtele.[Source: Catharine Paddock PhD, Medical News Today, March 29, 2012 ||*||]

“Haile-Selassie and colleagues say the partial foot fossil, which was discovered in February 2009, indicates that more than one species of early human ancestor with different means of locomotion, one walking upright, and the other climbing trees, existed between 3 and 4 million years ago: "The Burtele partial foot clearly shows that at 3.4 million years ago, Lucy's species, which walked upright on two legs, was not the only hominin species living in this region of Ethiopia," said Haile-Selassie in a statement. "Her species co-existed with close relatives who were more adept at climbing trees, like 'Ardi's' species, Ardipithecus ramidus, which lived 4.4 million years ago," he added. ||*||

“Lucy's big toe is aligned with the other four toes, for walking on two legs, like we do. But the Burtele foot apparently has an opposable big toe, like a thumb, allowing the foot to grasp branches. This is like the earlier Ardi, and similar to modern apes. The researchers write in their paper that the opposing big toe "not only indicates the presence of more than one hominin species at the beginning of the Late Pliocene of eastern Africa, but also indicates the persistence of a species with Ar. ramidus- like locomotor adaptation into the Late Pliocene". ||*||

20120202-australopithecus_sediba endocast.jpg
Australopithecus sediba endocast
“Haile-Selassie said other features of the Burtele foot show it did not belong to an ape, confirming that it is is truly a hominin, report Nature News, who also report that Daniel Lieberman, an anthropologist at Harvard University in Cambridge, Massachusetts, who was not involved in the study, agrees. Lieberman said the Burtele foot is "very much like the Ardipithecus foot, which I believe had many hominin features, so it's likely to be a hominin". ||*||

“Co-author and project co-leader Dr Bruce Latimer of Case Western Reserve University said they were shocked by the discovery. They had never seen bones like this before: "While the grasping big toe could move from side to side, there was no expansion on top of the joint that would allow for expanded range of movement required for pushing off the ground for upright walking. This individual would have likely had a somewhat awkward gait when on the ground," he explained. ||*||

“The researchers haven't been able to assign the Burtele foot to a species because there is no skull or dental elements to go with it. The foot was found under a layer of sandstone and the researchers used a radioactive dating method called argon-argon to determine its age. The argon-argon method uses the ratio of radioactive potassium-40 in a sample of rock to the amount of its decay product, argon-40, to work out the age of the rock, which in this case was found to be 3.46 million years. ||*||

“Co-author Dr Beverly Saylor, also of Case Western Reserve University, said nearby fossils of fish, crocodiles and turtles, as well as the physical and chemical properties of the sediments, indicate the surrounding area was once a "mosaic of river and delta channels adjacent to an open woodland of trees and bushes". "This fits with the fossil, which strongly indicates a hominin adapted to living in trees, at the same time 'Lucy' was living on land," she added. The finding adds weight to the idea that human evolution is not a simple linear progression from apes but a more complex affair.” ||*||

Image Sources: Wikimedia Commons

Text Sources: National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Nature, Scientific American. Live Science, Discover magazine, Discovery News, Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Time, Newsweek, BBC, The Guardian, Reuters, AP, AFP and various books and other publications.

Last updated April 2024

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