The Incomplete Story of Human Evolution

August 30, 2011

Human evolution is the history of the genus Homo, including the emergence of our ancestors, Homo sapiens, as a distinct species and as a unique category of hominids (“great apes”) and mammals. Human evolution is the history our origin. Human evolution is the history of a struggle for survival. Human evolution is the history of conflict between scientists and clergymen since 200 years ago. Human evolution is the history of conflict between myth and truth. Human evolution is the history of the conflict between myths and facts. Human evolution is the history of conflict between fanatics and intellects. Charles Darwin wrote in his autobiography: “My ‘Descent of Man’ was published in February, 1871. As soon as I had become, in the year 1837 or 1838, convinced that species were mutable productions, I could not avoid the belief that man must come under the same law. Although in the ‘Origin of Species’ the derivation of any particular species is never discussed, yet I thought it best, in order that no honorable man should accuse me of concealing my views, to add that by the work “light would be thrown on the origin of man and his history.” But when I found that many naturalists fully accepted the doctrine of the evolution of species, it seemed to me advisable to work up such notes as I possessed, and to publish a special treatise on the origin of man.” Darwin’s ‘Descent of Man’ was the first attempt to discovering the story of Human Evolution. The fanatics attacked Darwin, but he said : “Disbelief crept over me at a very slow rate, but was at last complete. The rate was so slow that I felt no distress, and have never since doubted even for a single second that my conclusion was correct. I can indeed hardly see how anyone ought to wish Christianity to be true; for if so the plain language of the text seems to show that the men who do not believe, and this would include my Father, Brother and almost all my best friends [that were good guys], will be everlastingly punished. And this is a damnable doctrine ” . Since that time, many fanatics and orthodox have fought against Darwin and the story of human evolution. Many of them think that the story of humans is a 5 thousand years story !, and call it “Biblical truth”. Even now, many fanatics and orthodox believe in this imaginary truth, this stupid myth. The story of human evolution is still incomplete, but we are sure that the old myths are certainly false. We know that the evolutionary history of the primates can be traced back 65 million years, as one of the oldest of all surviving placental mammal groups. Now lets take a look at the incomplete story of Human Evolution.

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Homo was evolved from a common ancestor somewhere in the past that served to separate them from the apes. Human origin is based on dated fossil remains of the various hominid existence. “Each bit of fossil evidence is like a piece to a complex puzzle. As more pieces fit into place, however, the picture becomes more complex and more questions are generated. We are still at the stage where new evidence generates more questions than answers, and we have no idea how complex the final picture that emerges will be”, the experts say. Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by fossils found in Kenya and Greece. Molecular evidence suggests that between 10 and 5 million years ago, first the gorillas, and then the chimpanzees (genus Pan) split off from the line leading to the humans; human DNA is approximately 98% identical to that of chimpanzees when comparing single nucleotide polymorphisms . The hominid lineage probably evolved 10 and 5 million years ago. The first point to make is that the earliest known species is “Australopithecus afarensis” have been dated between 4 and 3 million years ago. All other hominid species are dated later than 3 million years ago. The fossil gap between 4 and 5 to 8 million years ago has caused serious problems in determining the earliest ancestors of the modern African apes. Australopithecus afarensis fossils were discovered in Hadar, Ethiopia named Lucy. Australopithecine afarensis was adapted to bipedalism, appear apelike above the neck and humanlike below the neck and dated 3 to 3.5 million years ago . In 1959 the Leakeys found a 1.75 million year old, well preserved Australopithecine skull. Also Mary Leakey discovered the famous Laetoli footprints of 3 hominid dated 3.5 million years ago and was bipedal. A. afarensis still retained the ability to climb trees. Brain size was between 300-500cc. They were primarily vegetarian. Homo habilis was called the handy man because tools were found with his fossil remains. This species existed between 2.5 and 1.5 million years ago. The brain size in earlier fossil specimens was about 500cc to 800cc . Richard Leakey in Kenya uncovered many hominid fossils. One find was the most complete Homo habilis skull. The species brain shape shows evidence that some speech had developed. Habilis was about 5′ tall and weighed about 100 pounds. In Omo Valley, Ethiopia, Homo habilis remains were found to be contemporary with Australopithecus finds.

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Homo erectus lived between 1.8 million and 300,000 years ago. It was a successful species for a million and a half years. Brain size was between 900cc to 1200cc. The species definitely had speech. Erectus developed tools, weapons and fire and learned to cook his food . He traveled out of Africa into China and Southeast Asia and developed clothing for northern climates. He turned to hunting for his food. Only his head and face differed from modern man. Like habilis, the face had massive jaws with huge molars, no chin, thick brow ridges, and a long low skull. Though proportioned the same, he was sturdier in build and much stronger than the modern human. In 1894, the first Homo erectus called Java Man was dug from the banks of an Indonesian river, his discoverer Eugene Dubois triumphantly declared him the missing link between apes and humans. There was much resistance to accepting Neandertal and Homo erectus as human ancestors. In 1925, Raymond Dart found the skull of a young child in South Africa, Australopithecus africanus, with both human and apelike characteristics. Much older than anything yet found, it was eventually placed at the beginning of the line of human ancestors, so that the theoretical sequence was Australopithecus, living a few million years ago; Homo erectus, about half a million years old; Neandertals, living between 100,000 and 30,000 years ago; and Cro-Magnon, about 40,000 years ago. In 1972, Richard Leakey at Lake Turkana discovered the almost complete skeleton of a juvenile Homo erectus- like being about 1.5 million years old, much older than those that had been found in Asia. Then the simple picture was beginning to blur. Another important find was Don Johanson’s discovery in Ethiopia in 1974 of Australopithecus afarensis, better known as Lucy, estimated to be between 3 and 4 million years old. More and more hominid bones have also surfaced in Asia. Between 1985 and 1988 excavations in the Lunggupo Cave in Sechuan, China, produced Homo erectus-like remains dated by Chinese scientists as old as 1.9 million years, but some think they compare better with Homo habilis-like beings. Choukoutien cave in Dragon Bone Hill, China, has provided us with numerous Homo erectus remains as well as many interesting artifacts. The tools have been manufactured from quartz using a flake process. Examination of the site has revealed that the people who used this site were part of a hunter-gatherer society.In the 1990s discoveries of new types of hominids continued to make news, such as Ardipithecus ramidus in Ethiopia, estimated to be 4.4 million years old, and Australopithecus anamensis in Kenya, 4.2 million years old .

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There are two main theories about the descent of modern man, both with staunch supporters. The Multiregional Model holds that modern man evolved out of Homo erectus in different regions of the world more or less simultaneously. It involves little population migration, and transitional fossils should be found everywhere. The other theory holds that modern man evolved somewhere in Africa, and from there spread all over the world, replacing existing archaic hominid populations. This Out of Africa Model implies that extensive migration took place. According to the Out-of-Africa model, developed by Chris Stringer and Peter Andrews, modern Homo sapiens evolved in Africa 200,000 years ago. Homo sapiens began migrating from Africa between 70,000 – 50,000 years ago and eventually replaced existing hominid species in Europe and Asia. According to the Toba catastrophe theory, the super-eruption of Lake Toba on Sumatra island in Indonesia roughly 70,000 years ago had global consequences, killing most humans then alive and creating a population bottleneck that affected the genetic inheritance of all humans today. That time was the best time for the religious fanatics to say: “It’s the end of the times” ! But we know that all serious disasters in the past, were not a sign of the end of times. Sometimes many species became extinct, or even 99% of human beings were killed, but the life continued. It’s really stupid that with an earthquake or a hurricane many stupid fanatics talk about the end of times. In the past 3 billion years, since the first life was born in earth, there was many giant catastrophic events and many mass extinctions, in which more than 90% of all animate objects became extinct, but now with each natural disaster the stupid people talk about the end of times. Anyway, If the Multiregional Model is correct, early examples of modern humans should appear simultaneously throughout the Old World, which is not yet seen in the fossil record. But the Out of Africa Model gained support from research using female mitochondrial DNA (mtDNA) and the male Y chromosome. In the 1980s, the mitochondrial DNA research was used to show that all living humans could trace part of their genetic inheritance to a single female -a Mitochondrial Eve- who lived in Africa between 150,000 and 100,000 years ago. These results have been severely criticized, however, as too ambiguous and as supposing too fast a molecular clock rate. The researchers assumed it to be 2-4%, while others are of the opinion that 0.7% is more accurate, which would make the ancestral Eve 800,000 years old . The experts say: “Mitochondrial Eve was not the first female human. Homo sapiens evolved in Africa around 300,000 years ago, and the first hominids characterized by their unique bipedal stature appeared nearly two million years before that. Yet despite humans having been around for almost 30,000 years, Eve is exceptional because hers is the only lineage from that distant time to survive to the present day. Simply put, Eve was a survivor “. A maternal line can become extinct for a number of reasons. A woman may not have children, or she may bear only sons (who do not pass her mtDNA to the next generation). She may fall victim to a catastrophic event such as a volcanic eruption, flood, or famine, all of which have plagued humans since the dawn of our species.

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There is many unanswered questions about human evolution. One major issue is why and how did bigger brained, tool-using Homo evolve from a group of apelike beings such as Australopithecus? One popular hypothesis is the impact of environment and climate. Between 2 and 3 million years ago the drier African climate shrank the rainforest-like areas in which these early creatures lived, partly on the ground and partly in the trees. Open savanna land was increasingly dangerous to the relatively defenseless Australopithecus, who consequently died out. But a small group, under tremendous pressure for increase of intelligence, adapted and survived by their wits, a process reflected in the increasing brain size found in Homo habilis. Some defenders of the Out of Africa Model, admit that the exact cause and timing of the evolutionary split of those apes who elected to remain in trees (the ancestors of modern gorillas and chimpanzees) from those who chose life on the plains and evolved into hominids remains a mystery. That environment and changing climate can force species to move to different areas or cause their extinction is one thing. That this change might induce species to become more intelligent and then turn into another species may be too big a step. It’s one of the main unanswered questions. But the hypothesis of a common ancestor is very strong. Molecular research in the 1960s claimed that humans and chimpanzees diverged from each other some 5 to 7 million years ago, and gorillas and orangutans diverged earlier. “Humans in general are biologically highly homogeneous, and the interpretation is that mankind only recently evolved from one tight little group and as such is a very young species. The mitochondrial DNA of an Eskimo and an Australian Aborigine are more genetically alike than that of two unrelated gorillas from the same forest. Alan Templeton has warned against the assumption that a gene tree is the same as a population tree. The former reflects the evolutionary history of a particular piece of DNA, while the latter indicates the movements of individuals and all the genes these groups carry”, the experts say.

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Finds of prehistoric humans have been recorded for only the last 150 years. Before this the creation myths were relied on, so that remains of extinct animals and men were not recognized or acknowledged for what they were. Now, the story of Human Evolution is not a complete stroy. We don’t know many things about the past, its species, its environment, its environmental changes and disasters, etc. We don’t know why almost all groups of Homo extinct, and just Homo sapiens remain. We know that they were not the smarter or the stronger species ! Neanderthalensis lived in Europe and the Mideast between 150,000 and 35,000 years ago. Neanderthals coexisted with the Homo sapiens . His jaw was massive and he had a receding forehead, like erectus. Brain sizes averaged larger than modern man at about 1450cc but the head was shaped differently, being longer and lower than modern man. He was a massive man at about 5’6″ tall with an extremely heavy skeleton that showed attachments for massive muscles. He was far stronger than modern man . Homo sapiens first appeared about 120,000 years ago. Modern humans have an average brain size of about 1350cc. The earlier Homo sapiens provides the bridge between erectus and the later Homo sapiens during the period 200,000 to 500,000 years ago. Many skulls have been found with features intermediate between the two. Brain averaged about 1200cc and speech was indicated. It still is a mystery that why a smarter and stronger species became extinct, but our ancestors, Homo sapiens, survived. It is not known whether he was of the same species and disappeared into the Homo sapiens gene pool or he may have been crowded out of existence by the Homo sapiens. Some experts say: “Studies on Neanderthal body structures show that they needed more energy to survive than any other species. Their energy needs were up to 100-350 calories more per day comparing to projected anatomically modern human males weighing 68 kg and females 60 kg. When food became scarce, this difference may have played a major role in the Neanderthals’ extinction “. It’s not a complete or totally acceptable explanation. In the recent days, the media reported: “Our ancestors, Homo sapiens, were so horny and had s-e-x with Neanderthals ! They carry immune genes that originated in Neanderthals and a related species. The Neanderthals contributed up to 4% of modern Eurasian genomes. But these genes may have come at a price”. We would write more about it later.

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Now, most of what makes us human is invisible. We don’t know many things about the past, and about our ancestors. We don’t know many thing about the history of earth and the life on earth. We don’t know many things about the universe and the history of universe. Compared to what we don’t know, what we know is like a drop in the ocean. But we can be sure that the stupid myths about the past and the origin of human is crap and nonsense. Some say: “The truth and knowing the truth can be scary and chilling. But accepting the stupid myths, only because they are less scary is very stupid. The people at the age of Galileo, thought that earth is center of the whole universe, and the sun and the universe orbited earth. For them the truth was very very scary. It was very very scary for them, If earth was just one of planets of the Solar system; if earth was a planet like other planets, one of billions of billions planets in the universe They run away from the reality, because it was too scary. Now, we know the truth about our planet, but it’s not too scary. We want to know the truth about ourselves, our ancestors, and the universe even if it seems too scary for fanatics. We want to know the truth, even if it’s too scary”.

For more information, you can check here, http://www.becominghuman.org/, and find one of the best resource and learning software about Human Evolution.