1. Referring to \"The Great Leap Forward\" what human behaviors have been found
ID: 1254789 • Letter: 1
Question
1. Referring to "The Great Leap Forward" what human behaviors have been found in the investigation of Neanderthal societies?2. In terms of technological but also social development, what do you think was the significance of the Bronze Age?
3. What are some of the considerations and concepts behind planet-wide laws? In your opinion, is this a healthy step forward for humankind?
4. Identify one emerging technology, and evaluate its future prospects by identifying the cultural and social factors that may prevent or promote its successful application. Use concrete details to support your answer.
Explanation / Answer
The human body is the end product of a long period of evolution, stretching back millions of years. In the case of some aspects of our body, the ancestry goes back not just a few million years, but hundreds of millions. The basic layout of the human body, for example, is that of the vertebrates (being bilaterally symmetrical, organized around the backbone) and of the reptiles and amphibians (in having a pair of hind limbs and forelimbs, each with five digits — fingers or toes — at the end of them). But like every species, humans have a shape that is unique to themselves. Among primates, our closest evolutionary relatives, humans have three features that stand out — upright posture and walking, a relatively large brain, and relative hairlessness. Most primates live in trees, and they do so like all mammals by using all four limbs (or in the case of spider monkeys, five — their tails are also prehensile and can grasp things). Their hands and feet can both be used for grasping. In this sense, all non-human primates are quadrupedal. In the case of something like an orang utan, legs and arms, hands and feet are equally mobile and dextrous, and in a way all act more like arms than legs — for holding and grasping, rather than support. With baboons the forelimbs and hindlimbs are both rather leg-like, and support the animal as it moves quadrupedally over the ground, rather like a dog. For the gibbon, the only truly arm-swinging primate, the arms are long and flexible, and the legs, short and reduced — basically to get them out of the way as the owner brachiates through the trees. Everything about the human body is either a retention of these basic characteristics, or else has been modified by evolution. The grasping hand, the relatively mobile shoulder, the eyes that look forward with stereoscopic vision, are all part of the human being's ancient primate heritage. Each evolved for some reason in our past, long before any movement towards the human condition, but has remained useful and has been built upon. The close-set eyes that look directly forward, with overlapping fields of vision, evolved among the earlier primates, to allow them to judge distances in three-dimensional space — an essential part of leaping perilously from one tree branch to another. The ability to co-ordinate this vision with dextrous hand movements is an old evolutionary heritage, but one that is used every time we catch a ball or calculate whether it is safe to overtake a car at 100 km per hour. While our body is a cumulative and often messy mix of this ancient past, it is also the product of a unique evolutionary history shared with no other living primate. It is often said that humans are the most generalized of species, lacking all the specializations that characterize other animals such as giraffes, with their long necks, or elephants, with their trunks. In actual fact, as primates we are very specialized in one way — bipedalism. Unlike virtually all other primates, we are highly dedicated ground-dwellers, and indeed are fairly poor at climbing and clambering in trees. Our ability to walk upright habitually and easily is our most distinctive and in many ways most divergent characteristic. It has also shaped virtually all aspects of our body, from head to toe. Our foot is effectively a highly sprung platform, with arches in two directions to take the endless pounding of hitting the ground, and to push off into the next stride. It is heavily built compared with the feet of monkeys and apes, and has lost any ability to grasp. The knee is also built to take pressure, being large, and heavily constrained in sideways movement. The leg as a whole is very long, to ensure a large stride. The pelvis is perhaps the most modified part of the body, being turned from a long baton for connecting upper and lower parts of the body, to a large bowl to take all the weight of the upper body, which is now resting entirely on two legs. The vertebral column is also robust. Unlike the back of a quadruped, which is built with a single arch like a cantilevered bridge, the human spine is S-shaped. The head is also modified, being perched more vertically on the spine. The overall impression of a human from an evolutionary perspective is a tall, cylindical shape, a linear design. There has been considerable debate as to the evolutionary pressures that have shaped the human body, and it looks as if there are two main factors involved. The first is that bipedalism is an energy-saving way of moving on the ground: since our ancestors had to cope with the disappearance of forests, and search widely for food in dry African environments, it was the most evolutionarily effective way, turning an arm-swinging, tree-dwelling ape into a terrestrial specialist. The other factor is temperature. The open savannas where the earliest bipeds evolved were hot, with little shade, and the effect of the sun would have been severe. One of the effects of an upright posture is to reduce the area of the body that receives direct sunlight, and to remove more of it away from the reflected heat of the ground. The human body, then, was forged by selection in the heat of the more open plains of Africa. Evolution is the process of change over time, over thousands and millions of years. The fossil record has shown that the basics of bipedalism go right back to the roots of our evolutionary history, back to over four million years ago, soon (in evolutionary terms) after our ancestors diverged from the ancestors of the living chimpanzees, our closest relatives. The modern form of bipedalism, with the cylindrical, linear pattern, is probably about two million years old. With bipedalism would have come other changes. The hand, no longer needed to support the body in movement, became the highly dextrous and finely-tuned structure that we use today for so many activities. The upright stance is such a universal and uniform human characteristic that it is taken totally for granted: it is the essence of humanity. Around the world, though, the human body comes in enormous variety — tall, short, fat, thin, hairy, smooth, dark, and light. Unlike the basic upright body plan, these variations are not millions of years old, but just a few tens of thousands or even less. But they are still the product of evolution. Once again the environment has played a major part. Although humans vary in the amount of hair cover they have, they are, by comparison with apes, largely hairless. This is again a response to heat. Humans have evolved a copious sweating system — we use the evaporation of moisture from the skin to cool our body, and this works more effectively where the air can move freely over the skin — that is, where there is no hair. As a whole, therefore, the species is ‘naked’ — not actually hairless, but with a miniaturized hair cover. And those people who have a long history of living in the hotter parts of the world are the most hairless. Skin colour follows this pattern, with darker skins, produced by higher levels of melanin, acting as a compensatory mechanism to reduce the effect of high levels of solar radiation on the skin. Body shape is also affected by the environment — larger, shorter-limbed bodies are better at keeping in heat, where thin, long-limbed individuals are better at dissipating heat. As a result, people who live at higher latitude have shorter limbs, and are often robustly built; people in the tropics are small, linear, and lean. While the human body has evolved to suit the environment, especially the temperature, it has been affected by one other major factor — sex. Evolution is driven by selection — the survival of those best suited to the environment — but Darwin pointed out that there were two elements to this; natural selection and sexual selection. Most of the characteristics described so far have been the product of natural selection, but much of the human body is probably the result of how males and females have chosen their mates, and how well they are able to reproduce. Out of this has arisen the differences between the sexes. Some of these differences have a direct function — women have wider hips than men, compensating for the narrower birth outlet forced by bipedalism. Others are probably related to the preferences of men or women — larger breasts and curvaceous hips in women, for example. These secondary sexual characteristics may have their basis in some function, but are as much a signal and a symbol, and selected as such — in this case, a signal of fertility. Men also give signals with their bodies — simple ones related to strength and size, but also more subtle ones, such as grey hair or baldness as a sign of having lived a long time — and therefore being a successful male. Most characteristics, though, are a mixture of the sexual and functional. Men often prefer women who are more curvaceous, which is often related to fat deposition — women lay down fat more easily than men. This fat is also necessary for ensuring that a woman is well-nourished, and thus better able to withstand the costs of pregnancy and lactation. Women may prefer large, strong men, but such men may also be better at other things, such as hunting or fighting, and thus better adapted. In the end, the evolution of the human body is a seamless mix of sex, reproduction, activity, and environment; it is also a mix of the very old and the very new, and over evolutionary time has changed and shifted. In some ways it is a sleek and efficient machine; in others, it is full of flaws. In this sense it is like any other evolutionary product, a compromise between all the demands placed on it during the course of the many different lives that humans have to live, have lived in the past, and will live in the future.
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