Post by Galadriel on Jul 23, 2007 11:54:34 GMT
I would like to teach you a bit about the evolution of men. There are many primitives that paved the path to the humans we are now and each of them are interesting to study. It was one of my favorite topics in history class, but sadly enough I only learned about them in Latin class wich lasted one year.
I've done some research on wiki to find the English names, so pardon me for copying those texts.
Long live the internet! ;D
Human evolution is the part of biological evolution concerning the emergence of humans as a distinct species. It is the subject of a broad scientific inquiry that seeks to understand and describe how this change and development occurred. The study of human evolution encompasses many scientific disciplines, most notably physical anthropology, linguistics and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominins, such as the australopithecines.
An artist's impression of the now extinct species hominin Homo neanderthalensis.
I've used a picture of Elliot, I hope he doesn't mind too much? Thanks Konrad for giving me the picture ;D
The first Neanderthal man was found 1856 but there are sources that there are earlier foundings around 1830.
By 1859, the morphological similarity of humans to certain great apes had been discussed and argued for some time, but the idea of the biological evolution of species in general was not legitimized until Charles Darwin published On the Origin of Species in November of that year. Darwin's first book on evolution did not address the specific question of human evolution: "Light will be thrown on the origin of man and his history," was all Darwin wrote on the subject. Nevertheless, the implications of evolutionary theory were clear to contemporary readers.
Since the time of Carolus Linnaeus, scientists have considered the great apes to be the closest relatives of human beings, based on morphological similarity. In the 19th century, they speculated that the closest living relatives of humans are chimpanzees and gorillas. Based on the natural range of these creatures, they surmised that humans share a common ancestor with other African apes and that fossils of these ancestors would ultimately be found in Africa.
It was not until the 1920s that hominid fossils were discovered in Africa. In 1924, Raymond Dart described Australopithecus africanus. The type specimen was the Taung Child, an australopithecine infant discovered in a cave deposit being mined for concrete at Taung, South Africa. The remains were a remarkably well-preserved tiny skull and an endocranial cast of the individual's brain. Although the brain was small (410 cm³), its shape was rounded, unlike that of chimpanzees and gorillas, and more like a modern human brain. Also, the specimen exhibited short canine teeth, and the position of the foramen magnum was evidence of bipedal locomotion. All of these traits convinced Dart that the Taung baby was a bipedal human ancestor, a transitional form between apes and humans.
The australopithecines are now thought to be immediate ancestors of the genus Homo, the group to which modern humans belong. Both australopithecines and Homo sapiens are part of the tribe Hominini, but recent data has brought into doubt the position of A. africanus as a direct ancestor of modern humans; it may well have been a dead-end cousin. The australopithecines were originally classified as either gracile or robust. The robust variety of Australopithecus has since been reclassified as Paranthropus, although it is still regarded as a subgenus of Australopithecus by some authors.
In the 1930s, when the robust specimens were first described, the Paranthropus genus was used. During the 1960s, the robust variety was moved into Australopithecus. The recent trend has been back to the original classification as a separate genus.
Another 20 years would pass before Dart's claims were taken seriously, following the discovery of more fossils that resembled his find. The prevailing view of the time was that a large brain evolved before bipedality. It was thought that intelligence on par with modern humans was a prerequisite to bipedalism. (bipedalism= Bipedalism is standing, or moving for example by walking, running, or hopping, on two appendages (typically legs). An animal or machine that usually moves in a bipedal manner is known as a biped)
Hominin species distributed through time
I'm not gonna discuss them all, but the most known of them are the Austalopitec, the Homo Erectus, the Homo Habilis, Homo neanderthalensis, Homo Sapiens and the homo Sapiens Sapiens.
We know most about them, their abilities to survive and their skills.
Homo habilis
Homo habilis lived from about 2.4 to 1.5 million years ago (mya). H. habilis, the first species of the genus Homo, evolved in South and East Africa in the late Pliocene or early Pleistocene, 2.5–2 mya, when it diverged from the Australopithecines. H. habilis had smaller molars and larger brains than the Australopithecines, and made tools from stone and perhaps animal bones. One of the first known hominids, it was nicknamed 'handy man' by its discoverer, Louis Leakey. Some scientists have proposed moving this species out of Homo and into Australopithecus.
Homo erectus
The first fossils of Homo erectus were discovered by Dutch physician Eugene Dubois in 1891 on the Indonesian island of Java. He originally gave the material the name Pithecanthropus erectus based on its morphology that he considered to be intermediate between that of humans and apes. H. erectus lived from about 1.8 mya to 70,000 years ago. Often the early phase, from 1.8 to 1.25 mya, is considered to be a separate species, H. ergaster, or it is seen as a subspecies of erectus, Homo erectus ergaster.
In the Early Pleistocene, 1.5–1 mya, in Africa, Asia, and Europe, presumably, Homo habilis evolved larger brains and made more elaborate stone tools; these differences and others are sufficient for anthropologists to classify them as a new species, H. erectus. In addition H. erectus was the first human ancestor to walk truly upright. This was made possible by the evolution of locking knees and a different location of the foramen magnum (the hole in the skull where the spine enters). They may have used fire to cook their meat.
A famous example of Homo erectus is Peking Man; others were found in Asia (notably in Indonesia), Africa, and Europe. Many paleoanthropologists are now using the term Homo ergaster for the non-Asian forms of this group, and reserving H. erectus only for those fossils found in the Asian region and meeting certain skeletal and dental requirements which differ slightly from ergaster.
Homo neanderthalensis
Homo neanderthalensis lived from about 250,000 to as recent as 30,000 years ago. Also proposed as Homo sapiens neanderthalensis: there is ongoing debate over whether the 'Neanderthal Man' was a separate species, Homo neanderthalensis, or a subspecies of H. sapiens. While the debate remains unsettled, evidence from mitochondrial DNA and Y-chromosomal DNA sequencing indicates that little or no gene flow occurred between H. neanderthalensis and H. sapiens, and, therefore, the two were separate species. In 1997, Dr. Mark Stoneking, then an associate professor of anthropology at Pennsylvania State University, stated: "These results [based on mitochondrial DNA extracted from Neanderthal bone] indicate that Neanderthals did not contribute mitochondrial DNA to modern humans… Neanderthals are not our ancestors." Subsequent investigation of a second source of Neanderthal DNA supported these findings. However, supporters of the multiregional hypothesis point to recent studies indicating non-African nuclear DNA heritage dating to one mya, although the reliability of these studies have been questioned.
Homo sapiens
Homo sapiens ("sapiens" means wise or intelligent) has lived from about 250,000 years ago to the present. Between 400,000 years ago and the second interglacial period in the Middle Pleistocene, around 250,000 years ago, the trend in cranial expansion and the elaboration of stone tool technologies developed, providing evidence for a transition from H. erectus to H. sapiens. The direct evidence suggests there was a migration of H. erectus out of Africa, then a further speciation of H. sapiens from H. erectus in Africa (there is little evidence that this speciation occurred elsewhere). Then a subsequent migration within and out of Africa eventually replaced the earlier dispersed H. erectus. This migration and origin theory is usually referred to as the single-origin theory. However, the current evidence does not preclude multiregional speciation, either. This is a hotly debated area in paleoanthropology.
Current research has established that human beings are genetically highly homogenous, that is the DNA of individuals is more alike than usual for most species, which may have resulted from their relatively recent evolution or the Toba catastrophe. Distinctive genetic characteristics have arisen, however, primarily as the result of small groups of people moving into new environmental circumstances. Such small groups are initially highly inbred, allowing the relatively rapid transmission of traits favorable to the new environment. These adapted traits are a very small component of the Homo sapiens genome and include such outward "racial" characteristics as skin color and nose form in addition to internal characteristics such as the ability to breathe more efficiently in high altitudes.
I hope this was an interesting lesson, next class will be about the tools they used.
Feel free to post comments, suggestions and pictures of course!
Class dismissed ;D
I've done some research on wiki to find the English names, so pardon me for copying those texts.
Long live the internet! ;D
Human evolution is the part of biological evolution concerning the emergence of humans as a distinct species. It is the subject of a broad scientific inquiry that seeks to understand and describe how this change and development occurred. The study of human evolution encompasses many scientific disciplines, most notably physical anthropology, linguistics and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominins, such as the australopithecines.
An artist's impression of the now extinct species hominin Homo neanderthalensis.
I've used a picture of Elliot, I hope he doesn't mind too much? Thanks Konrad for giving me the picture ;D
The first Neanderthal man was found 1856 but there are sources that there are earlier foundings around 1830.
By 1859, the morphological similarity of humans to certain great apes had been discussed and argued for some time, but the idea of the biological evolution of species in general was not legitimized until Charles Darwin published On the Origin of Species in November of that year. Darwin's first book on evolution did not address the specific question of human evolution: "Light will be thrown on the origin of man and his history," was all Darwin wrote on the subject. Nevertheless, the implications of evolutionary theory were clear to contemporary readers.
Since the time of Carolus Linnaeus, scientists have considered the great apes to be the closest relatives of human beings, based on morphological similarity. In the 19th century, they speculated that the closest living relatives of humans are chimpanzees and gorillas. Based on the natural range of these creatures, they surmised that humans share a common ancestor with other African apes and that fossils of these ancestors would ultimately be found in Africa.
It was not until the 1920s that hominid fossils were discovered in Africa. In 1924, Raymond Dart described Australopithecus africanus. The type specimen was the Taung Child, an australopithecine infant discovered in a cave deposit being mined for concrete at Taung, South Africa. The remains were a remarkably well-preserved tiny skull and an endocranial cast of the individual's brain. Although the brain was small (410 cm³), its shape was rounded, unlike that of chimpanzees and gorillas, and more like a modern human brain. Also, the specimen exhibited short canine teeth, and the position of the foramen magnum was evidence of bipedal locomotion. All of these traits convinced Dart that the Taung baby was a bipedal human ancestor, a transitional form between apes and humans.
The australopithecines are now thought to be immediate ancestors of the genus Homo, the group to which modern humans belong. Both australopithecines and Homo sapiens are part of the tribe Hominini, but recent data has brought into doubt the position of A. africanus as a direct ancestor of modern humans; it may well have been a dead-end cousin. The australopithecines were originally classified as either gracile or robust. The robust variety of Australopithecus has since been reclassified as Paranthropus, although it is still regarded as a subgenus of Australopithecus by some authors.
In the 1930s, when the robust specimens were first described, the Paranthropus genus was used. During the 1960s, the robust variety was moved into Australopithecus. The recent trend has been back to the original classification as a separate genus.
Another 20 years would pass before Dart's claims were taken seriously, following the discovery of more fossils that resembled his find. The prevailing view of the time was that a large brain evolved before bipedality. It was thought that intelligence on par with modern humans was a prerequisite to bipedalism. (bipedalism= Bipedalism is standing, or moving for example by walking, running, or hopping, on two appendages (typically legs). An animal or machine that usually moves in a bipedal manner is known as a biped)
Hominin species distributed through time
I'm not gonna discuss them all, but the most known of them are the Austalopitec, the Homo Erectus, the Homo Habilis, Homo neanderthalensis, Homo Sapiens and the homo Sapiens Sapiens.
We know most about them, their abilities to survive and their skills.
Homo habilis
Homo habilis lived from about 2.4 to 1.5 million years ago (mya). H. habilis, the first species of the genus Homo, evolved in South and East Africa in the late Pliocene or early Pleistocene, 2.5–2 mya, when it diverged from the Australopithecines. H. habilis had smaller molars and larger brains than the Australopithecines, and made tools from stone and perhaps animal bones. One of the first known hominids, it was nicknamed 'handy man' by its discoverer, Louis Leakey. Some scientists have proposed moving this species out of Homo and into Australopithecus.
Homo erectus
The first fossils of Homo erectus were discovered by Dutch physician Eugene Dubois in 1891 on the Indonesian island of Java. He originally gave the material the name Pithecanthropus erectus based on its morphology that he considered to be intermediate between that of humans and apes. H. erectus lived from about 1.8 mya to 70,000 years ago. Often the early phase, from 1.8 to 1.25 mya, is considered to be a separate species, H. ergaster, or it is seen as a subspecies of erectus, Homo erectus ergaster.
In the Early Pleistocene, 1.5–1 mya, in Africa, Asia, and Europe, presumably, Homo habilis evolved larger brains and made more elaborate stone tools; these differences and others are sufficient for anthropologists to classify them as a new species, H. erectus. In addition H. erectus was the first human ancestor to walk truly upright. This was made possible by the evolution of locking knees and a different location of the foramen magnum (the hole in the skull where the spine enters). They may have used fire to cook their meat.
A famous example of Homo erectus is Peking Man; others were found in Asia (notably in Indonesia), Africa, and Europe. Many paleoanthropologists are now using the term Homo ergaster for the non-Asian forms of this group, and reserving H. erectus only for those fossils found in the Asian region and meeting certain skeletal and dental requirements which differ slightly from ergaster.
Homo neanderthalensis
Homo neanderthalensis lived from about 250,000 to as recent as 30,000 years ago. Also proposed as Homo sapiens neanderthalensis: there is ongoing debate over whether the 'Neanderthal Man' was a separate species, Homo neanderthalensis, or a subspecies of H. sapiens. While the debate remains unsettled, evidence from mitochondrial DNA and Y-chromosomal DNA sequencing indicates that little or no gene flow occurred between H. neanderthalensis and H. sapiens, and, therefore, the two were separate species. In 1997, Dr. Mark Stoneking, then an associate professor of anthropology at Pennsylvania State University, stated: "These results [based on mitochondrial DNA extracted from Neanderthal bone] indicate that Neanderthals did not contribute mitochondrial DNA to modern humans… Neanderthals are not our ancestors." Subsequent investigation of a second source of Neanderthal DNA supported these findings. However, supporters of the multiregional hypothesis point to recent studies indicating non-African nuclear DNA heritage dating to one mya, although the reliability of these studies have been questioned.
Homo sapiens
Homo sapiens ("sapiens" means wise or intelligent) has lived from about 250,000 years ago to the present. Between 400,000 years ago and the second interglacial period in the Middle Pleistocene, around 250,000 years ago, the trend in cranial expansion and the elaboration of stone tool technologies developed, providing evidence for a transition from H. erectus to H. sapiens. The direct evidence suggests there was a migration of H. erectus out of Africa, then a further speciation of H. sapiens from H. erectus in Africa (there is little evidence that this speciation occurred elsewhere). Then a subsequent migration within and out of Africa eventually replaced the earlier dispersed H. erectus. This migration and origin theory is usually referred to as the single-origin theory. However, the current evidence does not preclude multiregional speciation, either. This is a hotly debated area in paleoanthropology.
Current research has established that human beings are genetically highly homogenous, that is the DNA of individuals is more alike than usual for most species, which may have resulted from their relatively recent evolution or the Toba catastrophe. Distinctive genetic characteristics have arisen, however, primarily as the result of small groups of people moving into new environmental circumstances. Such small groups are initially highly inbred, allowing the relatively rapid transmission of traits favorable to the new environment. These adapted traits are a very small component of the Homo sapiens genome and include such outward "racial" characteristics as skin color and nose form in addition to internal characteristics such as the ability to breathe more efficiently in high altitudes.
I hope this was an interesting lesson, next class will be about the tools they used.
Feel free to post comments, suggestions and pictures of course!
Class dismissed ;D
