This species apparently was descended from Ardipithecus ramidus , which lived around 4. Anamensis was bipedal but may still have been an efficient tree climber. The shapes of the arm and leg bones indicate that it was bipedal. The canine teeth are relatively large compared to later australopithecines and humans. The alignment of teeth in the jaw is somewhat rectangular, reminiscent of apes, rather than like the modern human parabolic dental arch like the McDonald's golden arches sign.
Anamensis remains have been found in what had been woodlands around lakes. Their diets were apparently mainly vegetarian with an emphasis on fruits and nuts. Australopithecus afarensis lived about 3. Skeletally, they were still somewhat transitional from earlier ape species.
This can be seen in their legs which were relatively shorter than those of the later australopithecines and humans. Afarensis also had slender curved fingers reminiscent of chimpanzees. Because of these anatomical characteristics, it has been suggested that they were less efficient bipeds and more efficient tree climbers than the later australopithecines. Afarensis canine teeth were relatively large and pointed, reminiscent of apes. They projected somewhat beyond their other teeth but not as much as in chimpanzees.
Some of the male afarensis had small sagittal crests. Australopithecus afarensis Lucy Australopithecus afarensis reconstructed appearance Kenyanthropus platyops reconstructed appearance Tim White and some other paleoanthropologists believe that there was considerable physical variation within the species Australopithecus afarensis.
They suggest that the recently discovered fossils classified as Kenyanthropus platyops 3. White discounts the flattened face of platyops as being due to the deformation of the bones by ground pressure after death.
Its discoverer, Meave Leakey, disagrees. She believes that platyops was a separate species and that it was more likely to have been the progenitor of humans. Additional hominin fossils from the crucial time period of million years ago must be discovered to conclusively determine the place of platyops in our evolution. Australopithecus africanus lived about 3.
Skeletally, they were less ape-like than earlier species of australopithecines but were still usually small and light in frame like afarensis. However, the teeth of africanus were in some ways more like humans than like afarensis.
Specifically, the front teeth of africanus were relatively large like ours and their canine teeth did not project beyond the others. Microscopic wear patterns on africanus teeth suggest a diet consisting of relatively soft foods, which very likely included some meat along with plants.
This does not necessarily imply efficient hunting skills. More likely, they obtained meat by scavenging what remained on the abandoned corpses of large animals killed by lions and other predators.
It is possible that they also did some hunting of small animals in much the same inefficient manner of chimpanzees today.
They probably ate insects and eggs as well. The classification of Australopithecus garhi is still very problematical. This Ethiopian fossil has been dated to 2. Largely for that reason, some paleoanthropologists have suggested that garhi is a variant of africanus.
However, several features of the head of garhi look more like a holdover from the older afarensis species. On the other hand, the relative lengths of the arms and legs of garhi are more reminiscent of the first humans.
The discovery of butchered animal bones with garhi suggests that their diet included at least some meat, as was the case with africanus. Paranthropoid Species. T he australopithecines have been referred to collectively as gracile species literally "gracefully slender" of early hominins. Most of them were relatively small, slender, and delicate boned compared to the somewhat more muscular, robust species paranthropoids that mostly came later.
However, this is not always a reliable descriptive distinction because the range of variation in physical appearance of the two groups of species overlaps.
Subsequently, some individual graciles were bigger than some of the robust ones. However, the robust species shared some characteristics of their heads that dramatically show that they had diverged from the evolutionary line that would become humans. They had larger faces and jaws accompanied by pronounced sagittal crests in the case of males. They also had much larger back teeth premolars and molars and smaller front ones incisors compared to gracile australopithecines and early humans who were alive at the same time.
Australopithecus gracile body Paranthropus robust body Paranthropus teeth upper human teeth lower Little is known about Paranthropus a ethiopicus the "black skull" other than it apparently was one of the earliest robust species--it lived about 2. So far, this species has been found only in East Africa. Since it had a smaller brain than the other robust species and it was early, aethiopicus is thought to be a transitional form from one of the gracile species that came before.
It had an unusually large sagittal crest shown below. Paranthropus robustus was a South African robust species that lived about 2. They had strong jaws and very large molar and premolar teeth with thick enamel. Males also had pronounced sagittal crests, though not as large as the species listed next. Paranthropus boisei was a super-robust East African species that lived about 2. They tended to be more massive and beefy-looking even than Paranthropus robustus. Male boisei were especially muscular.
Like their South African cousins, robustus , they had prominent sagittal crests and very large grinding teeth with thick enamel. These teeth would have been capable of cracking hard nuts and dry seeds. However, such food items may not have been important in their diet. Microscopic analysis of dental wear patterns and carbon isotope analysis of teeth indicate that what boisei predominantly ate was soft foods such as grasses, leaves, roots, and possibly even meat.
Early Hominin Body Size. The early hominins were significantly smaller on average than modern humans. Homo erectus, which lived all over the world 1. But both still followed the evolutionary trend of generally decreasing tooth size: The size of our jaw and teeth have slowly been shrinking over millions of years. They were adaptations to changing environmental conditions that are well documented during the Plio-Pleistocene.
Thanks to the huge variations in teeth between modern Homo sapiens and all its ancestors, teeth are a wonderful tool for identifying species. But how do scientists know if a particularly large or small tooth should be classified as a different species, or is just an example of variation within a species?
That was certainly the question surrounding a single ,year-old molar discovered in It was the smallest molar ever found in Africa during the Middle Pleistocene, which increases the amount of variation among all samples for the region. As to which species it belonged to, that has yet to be determined. Think a basketball player versus a horse jockey! For example, a jawbone with teeth found on Gibraltar and attributed to a young Neanderthal child was given the age of three years at its death, and showed slightly more accelerated tooth eruption than in Homo sapiens.
Other researchers have used similar methods to argue that development most similar to that of modern humans began following the emergence of Homo erectus.
While Erectus still had faster tooth development than our species, they were slower than the hominins that came before. Guatelli-Steinberg and her colleagues recently submitted a paper on the dental development of Homo naledi which seems to distinguish it from other early hominins, and she hopes their work will be just the beginning of studies into this newly discovered species. Editor's Note, July 3, This post initially misstated that humans arrived in Asia 80 to million years ago; it was actually 80 to thousand years ago.
Lorraine Boissoneault is a contributing writer to SmithsonianMag. She has previously written for The Atlantic, Salon, Nautilus and others. New species from Ethiopia further expands Middle Pliocene hominin diversity.
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What do they tell us about our early evolution?
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