The Evolution of Man
Humans have existed on the Earth for approximately 3.4 million years. At least, that's from when the oldest human ancestors have been found. The oldest known human is the fossil "Lucy," an Australopithecus, discovered by Donald Johnson and M. Taieb. Australopithecines looked more like primates than modern-day Homo Sapiens; they walked semi-upright, they had low, sloping foreheads, protruding jaws, almost no facial expressions, thick body hair, and were about three feet tall. Over three and a half million years, humans have evolved greatly. We have grown from 3 to almost 6 feet, lost most of our body hair, become slender and adapted to walking, and grown brains over three times as large as the first Australopithecines. Besides all this, humans (Homo Sapiens) have developed an advanced material culture. Now, instead of living in trees and digging food from the ground with sticks, we live in vast cities of millions and buy our food from the local grocery store with money (another recent development). Humans have come a long way, from Australopithecus to Homo Sapiens. But we are also like the primates in many ways, too. We have the same basic body structure. Their hands are essentially just like ours, except that they don't have opposable thumbs. Their feet are similar to ours, only with longer toes for gripping. And our faces are very similar as well. Nevertheless, we still have come a long way from living in trees to living in cities. Slowly, through hundreds of thousands of years, we mutated time and time again, natural selection ensuring that no harmful mutations continued. From the slow process of evolution, four distinct species emerged and died out, each giving way to its' successor: Homo Habilis, Homo Erectus, Homo sapiens Neanderthalesis, and finally, Homo sapiens Sapiens. We've come a long way over our brief (3.4 million years) existence on Earth.
The first major step leading to Homo sapiens Sapiens was walking upright, or becoming bipedal. The Australopithecines were the first to do this, albeit rather clumsily. Their gait was, judging by their bone structure, was unsteady at best, and they probably mainly were quadrupedal (walking on all fours). They also retained the ability to climb trees. The oldest Australopithecus fossil is Lucy, an Australopithecus Afarensis. Over 40% of her skeleton was found intact, making Lucy one of the most complete Australopithecus finds as well as the oldest. The Australopithecines had a brain about the size of an orange (400-550cc), prominent cheekbones, and heavily enameled molars. They were about three feet tall, and had small, underdeveloped thumbs. Their toes were also somewhat shorter than other primates. Australopithecines, while definitely possessing some human characteristics, were still much closer to the chimps and gorillas that we evolved from, so it is safe to assume that they lived similar lives to other primates. They probably, judging from arrangements of fossils at sites, lived in one place in small groups. It is assumed that, like gorillas, one male dominated a group of Australopithecines. We assume this because of their sexual dimorphism. Sexual dimorphism is a noticeable difference in the sizes of males and females in a species. It is usually the males who are larger; in the case of Australopithecines, the males were larger. We know they lived in groups because fossil groups of Australopithecines are often found with more than 5 individuals in the same place. One site had 13 dead in the same place. While Australopithecines are most likely direct ancestors of modern-day humans, they were still relatively unintelligent. Their tools, if any, were limited to sticks and rocks found on the ground. Australopithecines were vegetarians; even if they knew that animals were edible, they still had no reliable means of killing animals for food. That came with the evolution of Homo Habilis. About 2 million years ago, highly evolved Australopithecines made the fundamental realization that then can influence their environment; they made the first tools, began exploiting resources, and made the shift to Homo Habilis at the same time. Homo Habilis is the earliest known member of the Homo genus, and has been found only in Africa. Besides a brain size 50% larger than Australopithecus, Homo Habilis was taller, had an almost hairless face, and flatter nostrils. They were taller than Australopithecines, and were becoming omnivorous. Homo Habilis had, among other things, discovered that meat was edible. They began scavenging dead meat, and added it to their normal vegetarian diets. We know this because of their teeth. Homo Habilis had grown large incisors, just right for tearing chunks of meat. They also had grown wisdom teeth, or a third molar. They are also required for chewing meat. The most important development in Homo Habilis, however, is language. With their larger cerebral cortex, the had incredible (for the time) abilities in reasoning, thinking, and memory. They also hunted, which was a group activity requiring precision, accuracy, planning, and silence. Thus, instead of the grunts and shrieks of their ancestors, Homo Habilis probably developed hand signals and facial expressions which conveyed meaning for use in hunting parties; this was the first symbolic communication. These signals became more complex, and hand signals were developed to represent abstract concepts (good, evil, etc). Then, the hand signals became organized and combined with sounds to create a crude form of language. This, along with the tool culture that had come about, created the foundations of an advanced culture. Homo Habilis were completely bipedal, and had lost the tree-climbing ability with the hand and foot development. They had a greatly reduced brow ridge, and the beginnings of a chin. Homo Habilis was 3.7 to 4.2 feet tall on average. Homo Habilis had, as told above, made the first tools. They were primitive tools, and the most complex tool made was the chopper, the predecessor to the axe. Homo Habilis dominated Africa until about 1.6 million years ago, when Homo Erectus emerged, causing their eventual extinction.
Homo Erectus was the next step in human evolution, and had a much larger brain (1060 cc) than Homo Habilis. The name "Homo Erectus" means "Man who Walks Upright," which means practically nothing as all members of the Homo genus walked upright. There were very few physical changes from Homo Habilis to Homo Erectus besides the larger brain; the most noticeable changes were a lighter, more delicate jaw and smaller teeth. The brow-ridge was also slightly larger than Homo Habilis'. There was still almost no chin, and the forehead still sloped back, just not as much. Homo Erectus had developed tool-making to an art, chipping off small flakes instead of large flakes to get more control of the tools they were making; they also completely chipped off the surface of the stone they were working, making tools impossible to make with the tool-making styles of Homo Habilis. The standardized hand axe was invented by the Homo Erectus as well. Homo Erectus' greatest accomplishment, however, was leaving Africa. They were the first to cross over into Asia and Europe, spreading humans throughout most of the world. The first Homo Erectus fossil found outside of Africa were on the island Java from 1891 to 1894. Because of this, Homo Erectus was originally called the "Java Man." Because they were found on a island, we can surmise that there was an ice age going on when Homo Erectus began migrating. Homo Erectus did not make canoes and the only other way, besides swimming for miles, was crossing land bridges exposed only during ice ages. As the early humans moved away from the intense sunshine and heat of the equator, they began adapting to the lesser degrees of sun by a variation of the melanin in their skin; thus the humans of eastern Asia have a yellowish skin and Europeans tend towards white skin. Homo Erectus lived until about 100,000 years ago, when Homo sapiens Neanderthalesis took their place.
Homo sapiens Neanderthalesis, commonly knows simply as Neanderthals, lived almost entirely during the most recent Ice Age. Homo sapiens Sapiens are not directly descended from Neanderthals; Neanderthals evolved from Homo Erectus in Europe tens of thousands of years before Homo sapiens Sapiens evolved in Africa. The physical differences between Homo sapiens Neanderthalesis and Homo Erectus are great. While not much taller, Neanderthals were built very differently: they were very broad and stocky, with wide hips and a bow-legged stance. They had very large brains; they were larger, on average, than those of modern humans. Most of this development, however, was in the rear of the brain, which handled memory. Neanderthals probably could remember just about everything that had ever happened to them, but did not have the thinking power of modern humans. Homo sapiens Neanderthalesis also had a low, sloping forehead with a very dominant brow ridge, and no chin, looking more like Homo Habilis than Homo Erectus. The tools of the Neanderthals, though, were far superior to anything made before. Instead of using standard choppers and hand axes made of stone, Neanderthals used a technique called flint knapping to create four distinct types of tools: points for hunting, burins (chisels) for cutting grooves, borers for making holes in soft materials, and drills for making holes in harder materials. The clothing worn by Neanderthals was also different from Homo Erectus. Because of the fierce cold, Neanderthals wore thick, heavy animal skins in the long winter months to keep out the cold, whereas before only light clothing was worn. The society of Homo sapiens Neanderthalesis was very advanced, and was the first society where the old and sick were cared for instead of left to die. This evinces the importance of mental abilities in the Neanderthal society. Neanderthal culture was a patriarchy, dominated by the men. The men hunted animals while the women were subservient and gathered roots, berries and all manners of plants for food and medicine. Men were also the only ones allowed to participate in the holy ceremonies, led by male priests. It was a strict caste system, each person having a role in the group for their entire lives. It was unlike anything seen before. It was probably this strict, rigid society that was the downfall of Homo sapiens Neanderthalesis. They died suddenly, only a few thousand years after the first contact with Homo sapiens Sapiens. Nobody knows why, but competition between the two and the dilution of bloodlines through interbreeding are the two most favored theories. But for whatever reasons, Homo sapiens Neanderthalesis became extinct 35,000 years ago.
The death of Homo sapiens Neanderthalesis left Homo sapiens Archaic (Cro-Magnons) the dominant human species. Cro-Magnons were not significantly different from modern-day humans; Cro-Magnon is more of a societal name than a species unto itself. Homo sapiens Archaic was very different from Homo sapiens Neanderthalesis. They were tall and slender with almost no body hair. They had a high forehead, a rounded skull and no brow ridge. Another new addition was a protruding chin. In other words, if a Cro-Magnon were to walk down the street, you wouldn't be able to tell him apart from the other people. Cro-Magnons were very advanced; they had a complete vocal language, (Homo sapiens Neanderthalesis had an inferior voice box), and they had the most advanced tools in the world. Most of their tools were made of bone, and their clothes were made of leather sewn together with bone needles. There were also bone fishing hooks, and the first boats were made by the Cro-Magnons as well. In Homo sapiens Archaic society, the old and feeble were still cared for, and it was still a patriarchy (possibly this was acquired from the Neanderthals via cultural diffusion), but it was not a rigid caste system. It was a flexible, innovative system where both men and women did the hunting and gathering. Cro-Magnons also were the first to domesticate and ride horses. Homo sapiens Archaic were superior to Homo sapiens Neanderthalesis for a variety of reasons: they were better thinkers, they were faster, had more precise movements, and had greater technological capacity. Cro-Magnons were simply better equipped to handle the world. And the rest, they say, is history.
Modern humans do not all look alike, as you already know. Since they are spread out over such a vast region, and throughout so many climates, humans have had to adapt. They have had, to a small degree, evolve. Evolution occurs in small, almost imperceptible steps. There are small mutations from one generation to the next. Anyone possessing a helpful mutation is more likely to reproduce, carrying on the beneficial trait. Likewise, those with negative effects tend to die out. Returning to the climate example: people living closer to the equator have dark skin to prevent severe burning and possible skin cancer, while people living closer to the poles have whiter skin because the high amounts of melanin are no longer needed for that particular climate. These physical differences, though, are just that: physical. The underlying bodily functions and intelligence that define humans remain the same. Some people call those with different skin color different races. This is not true. Humans are a race. Calling someone with slanted eyes or dark skin a different race is like calling a long-haired cat a different species than tomcat. It is untrue and divisive, which is harmful to the human race. This is one of the few disadvantages to intelligence; creatures without intelligence aren't smart enough to perceive that others of their species are different from them if they have a different pattern on their fur. They don't, indeed they can't, make judgments based on appearances. They don't divide themselves any more than male from female. We, however, can make those judgments. And we often do, much to our detriment. Our over-analytical minds notice otherwise subtle differences and exaggerate them, almost always assuming themselves to be the superior ones. If we are to be successful in the future, dividing humans into separate races must be stopped.
In spite of all this divisive thinking, humans remain the most successful species on the planet. We have achieved a degree of intelligence unmatched by anything else; we have conquered nature, learned efficient use of natural resources, and have spread from Africa to every part of the globe. We have evolved from monkeys living in trees into thinking beings with the ability to alter their environments to almost any way we choose. And, we've developed an advanced culture. We live in enormous communities of people, we have highly specialized divisions of labor, and we have an intricate code of behavior. This is unique. No other creatures on Earth have this. But with this advancement comes responsibility. We have the power to do what we want to the Earth. We can preserve it or destroy it. Again, this is unique to humans. So far, we're doing a good job of preserving the Earth. But modern-day humans, Homo sapiens Sapiens, are still evolving. Just because this is where we are, doesn't mean this is where we stop. As the millennia pass, our culture and physical features will continue to improve and advance. Soon we won't even be confined to this planet anymore, and then we will truly have conquered it. And our responsibility for it will increase proportionately. Someday, a new species of humans will take the place of Homo sapiens Sapiens, and we will go the way of our ancestors. But until then, our job is to make the most of our existence here, and to make sure we stick around long enough for the next species to arrive. So far, things are looking pretty good.
This paper recieved an "A+", and is definitely NOT garbage. My professer even used it in a teacher's
instructional seminar, so it's definitely a good resource. Just so you know =)