Early Homonid Species: Australopithecus Genus


Figure 1.--This is an artist's conception of an 'Australopithecus afarensis' family. The most famous is of course 'Lucy'. 'A farensis' is the longest-living hominid species known. They thrived for more than million years. The various 'Australopithecus' species covered some 2 million years. They were bipedal and able to climb trees.

Australopithecus is an extinct genus of hominids, the direct ancestors of modern humans. This is the homonoid genus that diverged from earlier ape-like species. Australopithecus means 'southern ape' and is part of our evolutionary path. There were many species of Australopithecus. The precise number is indispute, in part because some proposed species may be simply specimens of known species which viverged from the mean. Australopithecus afarensis is a long-lived and relatively well studies species. Remains from more than 300 individuals have been found. This is a rather klarge number for early homonids. They have been found in East Africa (Ethiopia, Kenya, Tanzania) and dated to 3.85-2.95 million years ago. The finds in East Africa are largely due to the Great Rift Valleg which passes north to south through these countries. A. afarensis is known to have survived for more than 900,000 years, which is over four times greater than modern humans (Homo sapiens. And the relatively large number of findings may mean that it was a prolific species. The species is perhaps best known for Lucy. A. afarensis was very similar to chimpanzees, even more so than humans. The children grew very rapidly after birth and thus reached adulthood at an earlier age than modern humans. This meant A. afarensis had a shorter period of growing up and maturation than modern humans. This meant that the young received less parental guidance and socialization. A. afarensis was esentially a bridge between apes and humans, the missing link that was so often sought after Darwin published his concept of evolution. The various Australopithecus species had a mixture of ape and human characteristics. They tended to have apelike faces, a flat nose, a projecting lower jaw. The braincase was much smaller than that of modern man. This was an estimated 500 cubic centimeters which would be about 1/3 the size of a modern human brain. Australopithecus had long, strong arms with curved fingers. This would be the characteristics needed for climbing trees which provides insights into behavior and habitat. They had small canine teeth which was more like humans than apes. They also had a body that stood on two legs and commonly regularly walked upright. These adaptations meant that they could live in a wide range of environments. They could live both in trees and on the fround. This was surely a factor that enabled them to survive for about a million years over which timr climate and environments changed. Archaeologists and palaeontologists generally believe that Australopiths played a key role in human evolution. One of the australopith species is believed to have evolved into the Homo genus in Africa around 2 million years ago. A. africanus was initially regarded as ancestral to the genus Homo and some anthropologists identified Homo erectus as directly related. Anthopolgists have since found genus Homo fossils that are older than A. africanus, complicating the evolutioinary story.

Evolutionary Role

Australopithecus is a genus of early homonids that is now extinct. This is the homonoid genus that diverged from earlier ape-like species. Australopithecus means 'southern ape' aluding to Africn origins, and is part of our evolutionary path.

Species

There were many species of Australopithecus. The precise number is indispute, in part because some proposed species may be simply specimens of known species which viverged from the mean. This is difficult to work out because the fosil record is so limited. Australopithecus afarensis is a long-lived and relatively well studies species. Remains from more than 300 individuals have been found. This is a rather klarge number for early homonids. A. afarensis is known to have survived for more than 900,000 years, which is over four times greater than modern humans (Homo sapiens. And the relatively large number of findings may mean that it was a prolific species. The species is perhaps best known for Lucy. Other species include A. anamensis, A. bahrelghazali, A. deyiremeda (proposed), A. garhi, and A. sediba. The fosil record is very limited, except for A. Sediba. Often just a few fragments or teeth have been found for some of these species. Often there is some dount as to wether they truly constitute a separate species. Thus the precise human lineage is still unclear. For some hominid species of this time, such as A. robustus and A. boisei, some debate exists whether they constitute members of the same genus. If so, they would be considered 'robust australopiths', while the others would be 'gracile australopiths'. However, if these species do constitute their own genus, they may be given their own name, Paranthropus.

Chronology

Australopithecus first appeared about 4 million years ago and then different species spreading throughout the African continent. Australopithecine species went extinct sometime after about 2 million years ago.

Location

Australopithecus genus apparently evolved in eastern Africa, and nowhere else on earth. The findings clearly establish the African Genisus theories. Interestingly this is what Darwin and Wallace had believed, largely because it was in Africa that most of the great apes are found. Subsequent authors more influenced by racist beliefs had dismissed this idea. We have a a fairly good idea about the range of Australopithecus. Unlike Homo sepecies, Australopithecus never left Africa. They have been found in East Africa (Ethiopia, Kenya, Tanzania) and dated to 3.85-2.95 million years ago. The finds in East Africa are largely due to the Great Rift Valleg which passes north to south through these countries. The sites of Hadar, Ethiopia is where Lucy (AL 288-1) and the First Family (AL 333) was found. Another important site is Dikika, Ethiopia. Here the Dikika ‘child’ skeleton) was found. Laetoli in Tanzania is another important site which has given us the oldest documented bipedal footprint trails.

Characteristivs

A. afarensis was very similar to chimpanzees, even more so than humans. The babies grew very rapidly after birth and thus reached adulthood at an earlier age than modern humans. This meant A. afarensis had a shorter period of growing up and maturation than modern humans. Which would mean that the young received less parental guidance and socialization. A. afarensis was esentially a bridge between apes and humans, the missing link that was so often sought after Darwin published his concept of evolution. The various Australopithecus species had a mixture of ape and human characteristics. They tended to have apelike faces, a flat nose, a projecting lower jaw. The braincase was much smaller than that of modern man. This was an estimated 500 cubic centimeters which would be about 1/3 the size of a modern human brain. Australopithecus had long, strong arms with curved fingers. This would be the characteristics needed for climbing trees which provides insights into behavior and habitat. They had small canine teeth which was more like humans than apes. They also had a body that stood on two legs and commonly regularly walked upright.

Habitat

These adaptations of Australopithecus meant that they could live in a wide range of environments. Thus they were a species capable of sihnificant adaptation. They could live both in trees and on the ground. This was surely a factor that enabled them to survive for about a million years over which time climate and environments changed.

Tool Making

There was formany years no evidence that any of these Australopithecus species could fashion or extensively used tools. Thus they were generally seen as existing before the Stone Age. This is now being rethought. Radiometric dating is now allowing greater precission in dating. As a result, archeologists have found stone tools that are believed to be some 3.3 million old. They were found at Lomekwi 3 in Kenya. This places them 0.7 million years earlier than tolls made by Homo hablis. Although nothing is know about the people who made these tools, but given the age, they were mostly made by Australopithedid.

Behavior and Living Conditions

Recent findings have begun to attribute more human characteristics to Australopithecus than previously believed The fosil evidence is so limited tht antthropologists can only speculate as to behavior and life style. The spectcular finds of Sediba near Johaneberg, South Africa have enabled some assessmnents about behavior and life hitorty. Researchers speculate that they were vegetarians surviving on berries, fruits, roots, and grasses. The speculation as to man's earliest ancestors being killer apes (ala '2001 Space Odessy' and the work of Raymond Dart and Robert Ardrey) was clearly eronious.

Human Evolutionary Link

Archaeologists and palaeontologists generally believe that Australopiths played a key role in human evolution. One of the australopith species is believed to have evolved into the Homo genus in Africa around 2 million years ago. A. africanus was initially regarded as ancestral to the genus Homo and some anthropologists identified Homo erectus as directly related. Anthopolgists have since found genus Homo fossils that are older than A. africanus, complicating the evolutioinary story. And it is likely that some of these species could interbread, and additional factor complicating understanding the precise human lineage.







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Created: 4:46 AM 11/22/2015
Last updated: 4:46 AM 11/22/2015