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fandomhigh2006-02-01 10:26 pm
the-ascended.livejournal.com) wrote in fandomhigh2006-02-01 10:26 pm
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Anthropology 101, 6th Period
Daniel's bright-eyed and bushy-tailed today. Who knows why? I certainly don't
"We're getting further through our evolutionary timeline of man. I'm going to be talking about early transitional humans now.
Humans are members of the genus Homo. Modern people, on Earth, that is, are Homo sapiens, something I really hope you all knew already.
Now, in the past, it was incorrectly assumed that human evolution was a relatively straight forward sequence of one species evolving into another. We now understand that there were times when several species of humans and even other hominids were alive.
There may have been one or possibly two species of early transitional humans living in East Africa - Homo rudolfensis and Homo habilis. The few rudolfensis fossils that have been found are somewhat earlier, dating about 2.4-1.9 million years ago, while the more common habilis remains are around 2.0-1.5 million years old. Rudolfensis apparently was a bit taller and relatively larger brained on average. However, many paleoanthropologists consider the differences to be too slight to warrant a separate species designation. Some have suggested that rudolfensis were males and habilis were females. As a result, they classify them both as a single species - Homo habilis.
Early transitional human fossils were first discovered in 1960 by Louis and Mary Leakey at Olduvai Gorge in Tanzania. The Leakeys named them Homo habilis, which is Latin for "handy or skilled human", because they apparently made stone tools. Similar fossils were found at East Lake Turkana in Kenya by Richard Leakey's team of fieldworkers that began searching there in 1969. These latter specimens were named Homo rudolfensis after Lake Rudolf, which isthe former name for Lake Turkana.
So far, conclusive evidence of Homo habilis has been found only in the Great Rift Valley system of East Africa. However, their ultimate geographic range may have been somewhat larger. Early transitional human fossils also have been found in South Africa in the caves at Sterkfontein and Swartkrans in apparent association with australopithecines. However, not all paleoanthropologists agree that these fossils should be considered Homo habilis.
Early transitional humans had brains that on average were about 30% larger than those of the australopithecines. In fact, it is beginning with Homo habilis that our ancestors finally had brains that were consistently bigger than those of the great apes. Ajit Varki and his team of geneticists at the University of California San Diego campus have discovered a small genetic difference between humans and apes that may account for the progressive increase in the size of human brains. I won't bore you with the details of that.
As the early human cranium, or brain case, began to enlarge in response to increased brain size, the mouth became smaller. In comparison to the australopithecines, the early humans had smaller teeth, especially the molars and premolars. This suggests that they were eating somewhat softer foods. However, the body size of Homo habilis was not significantly larger than the early hominids that preceded them. The modern human body size began to appear with the next species in our evolution - Homo erectus.
"Okay, any questions about Homo habilis, before we move swiftly on to Homo erectus?"
By nearly 2 million years ago, some of the early transitional humans had evolved into a new, fully human species in Africa. Most paleoanthropologists refer to them as Homo erectus. However, a few researchers split them into two species - Homo ergaster and Homo erectus. We're just going to refer to them as Homo erectus though.
Homo erectus were very successful in creating cultural technologies that allowed them to adapt to new environmental opportunities. They were true pioneers in developing human culture and in moving out of Africa to populate tropical and subtropical zones elsewhere in the Old World. This territorial expansion most likely began around 1.8-1.7 million years ago, coinciding with progressively cooler global temperatures at the beginning of the Pleistocene Epoch. Surprisingly, however, Homo erectus remained largely unchanged anatomically until about 700,000-600,000 years ago. After that time, there apparently were evolutionary developments in features of the head that would become characteristic of modern humans. By half a million years ago, some Homo erectus were able to move into the seasonally cold temperate zones of Asia and Europe. This migration was made possible by greater intelligence and new cultural technologies, probably including better hunting skills and the ability to create fire.
The earliest Homo erectus were contemporaries of the late Homo habilis in East Africa for several hundred thousand years. This suggests that the immediate ancestor of Homo erectus was an early Homo habilis or possibly another yet to be discovered species of early humans. Homo erectus was a very successful human species, lasting at least 1.5 million years, though their numbers apparently remained relatively low. Some of them eventually evolved into our species, Homo sapiens. That evolutionary transition was well under way by 400,000 years ago but was not complete until 200,000-100,000 years ago and possibly even later in some regions.
"And thus ends my lectures today. Monday's homework, on my desk, please. And if you didn't hand in the homework from last week, I'd like that as well, please. Homework tonight, please, is on the anatomy of Homo erectus. And next week, we'llfinally be looking at the evolution of modern humans. Have a safe weekend."
"We're getting further through our evolutionary timeline of man. I'm going to be talking about early transitional humans now.
Humans are members of the genus Homo. Modern people, on Earth, that is, are Homo sapiens, something I really hope you all knew already.
Now, in the past, it was incorrectly assumed that human evolution was a relatively straight forward sequence of one species evolving into another. We now understand that there were times when several species of humans and even other hominids were alive.
There may have been one or possibly two species of early transitional humans living in East Africa - Homo rudolfensis and Homo habilis. The few rudolfensis fossils that have been found are somewhat earlier, dating about 2.4-1.9 million years ago, while the more common habilis remains are around 2.0-1.5 million years old. Rudolfensis apparently was a bit taller and relatively larger brained on average. However, many paleoanthropologists consider the differences to be too slight to warrant a separate species designation. Some have suggested that rudolfensis were males and habilis were females. As a result, they classify them both as a single species - Homo habilis.
Early transitional human fossils were first discovered in 1960 by Louis and Mary Leakey at Olduvai Gorge in Tanzania. The Leakeys named them Homo habilis, which is Latin for "handy or skilled human", because they apparently made stone tools. Similar fossils were found at East Lake Turkana in Kenya by Richard Leakey's team of fieldworkers that began searching there in 1969. These latter specimens were named Homo rudolfensis after Lake Rudolf, which isthe former name for Lake Turkana.
So far, conclusive evidence of Homo habilis has been found only in the Great Rift Valley system of East Africa. However, their ultimate geographic range may have been somewhat larger. Early transitional human fossils also have been found in South Africa in the caves at Sterkfontein and Swartkrans in apparent association with australopithecines. However, not all paleoanthropologists agree that these fossils should be considered Homo habilis.
Early transitional humans had brains that on average were about 30% larger than those of the australopithecines. In fact, it is beginning with Homo habilis that our ancestors finally had brains that were consistently bigger than those of the great apes. Ajit Varki and his team of geneticists at the University of California San Diego campus have discovered a small genetic difference between humans and apes that may account for the progressive increase in the size of human brains. I won't bore you with the details of that.
As the early human cranium, or brain case, began to enlarge in response to increased brain size, the mouth became smaller. In comparison to the australopithecines, the early humans had smaller teeth, especially the molars and premolars. This suggests that they were eating somewhat softer foods. However, the body size of Homo habilis was not significantly larger than the early hominids that preceded them. The modern human body size began to appear with the next species in our evolution - Homo erectus.
"Okay, any questions about Homo habilis, before we move swiftly on to Homo erectus?"
By nearly 2 million years ago, some of the early transitional humans had evolved into a new, fully human species in Africa. Most paleoanthropologists refer to them as Homo erectus. However, a few researchers split them into two species - Homo ergaster and Homo erectus. We're just going to refer to them as Homo erectus though.
Homo erectus were very successful in creating cultural technologies that allowed them to adapt to new environmental opportunities. They were true pioneers in developing human culture and in moving out of Africa to populate tropical and subtropical zones elsewhere in the Old World. This territorial expansion most likely began around 1.8-1.7 million years ago, coinciding with progressively cooler global temperatures at the beginning of the Pleistocene Epoch. Surprisingly, however, Homo erectus remained largely unchanged anatomically until about 700,000-600,000 years ago. After that time, there apparently were evolutionary developments in features of the head that would become characteristic of modern humans. By half a million years ago, some Homo erectus were able to move into the seasonally cold temperate zones of Asia and Europe. This migration was made possible by greater intelligence and new cultural technologies, probably including better hunting skills and the ability to create fire.
The earliest Homo erectus were contemporaries of the late Homo habilis in East Africa for several hundred thousand years. This suggests that the immediate ancestor of Homo erectus was an early Homo habilis or possibly another yet to be discovered species of early humans. Homo erectus was a very successful human species, lasting at least 1.5 million years, though their numbers apparently remained relatively low. Some of them eventually evolved into our species, Homo sapiens. That evolutionary transition was well under way by 400,000 years ago but was not complete until 200,000-100,000 years ago and possibly even later in some regions.
"And thus ends my lectures today. Monday's homework, on my desk, please. And if you didn't hand in the homework from last week, I'd like that as well, please. Homework tonight, please, is on the anatomy of Homo erectus. And next week, we'll