Diamonds are almost impossible to detect directly because they are so rare: very rich kimberlite pipes, the routes through which diamonds rise, may contain only three carats of diamonds per ton of kimberlite. Kimberlite begins as magma in Earth's mantle (the layer between the crust and the core). As the magma smashes through layers of rock, it rips out debris, creating a mix of liquid and solid material. Some of the solid material it brings up may come from a so-called diamond-stability field, where conditions of pressure and temperature are conducive to the formation of diamonds. If diamonds are to survive, though, they must shoot toward Earth's surface quickly. Otherwise, they revert to graphite or burn. Explorers seeking diamonds look for specks of "indicator minerals" peculiar to the mantle but carried up in greater quantities than diamonds and eroded out of kimberlite pipes into the surrounding land. The standard ones are garnets, chromites, and ilmenites. One can spend years searching for indicators and tracing them back to the pipes that are their source; however, 90 percent of kimberlite pipes found this way are barren of diamonds, and the rest are usually too sparse to mine.

    In the 1970's the process of locating profitable pipes was refined by focusing on the subtle differences between the chemical signatures of indicator minerals found in diamond-rich pipes as opposed to those found in barren pipes. For example, G10 garnets, a type of garnet typically found in diamond-rich pipes, are lower in calcium and higher in chrome than garnets from barren pipes. Geo-chemists John Gurney showed that garnets with this composition were formed only in the diamond-stability field; more commonly found versions came from elsewhere in the mantle. Gurney also found that though ilmenites did not form in the diamond-stability field, there was a link useful for prospectors: when the iron in ilmenite was highly oxidized, its source pipe rarely contained any diamonds. He reasoned that iron took on more or less oxygen in response to conditions in the kimberlitic magma itself—mainly in response to heat and the available oxygen. When iron became highly oxidized, so did diamonds; that is, they vaporized into carbon dioxide.

    Anthropologists once thought that the ancestors of modern humans began to walk upright because it freed their hands to use stone tools ,which they had begum to make as the species evolved a brain of increased size and mental capacity. But discoveries of the three-million-year-old fossilized remains of our hominid ancestor Australopithecus have yielded substantial anatomical evidence that upright walking Appeared prior to the dramatic enlargement of the brain and the development of stone tools. Walking on two legs in an upright posture (bipedal locomotion) is a less efficient proposition than walking on all fours (quadrupedal locomotion) because several muscle groups that the quadruped uses for propulsion must instead to provide the biped the biped with stability and control. The shape and configuration of various bones must likewise be modified to allow the muscles to perform these functions in upright walking. Reconstruction of the pelvis (hipbones) and femur (thighbone) of "Lucy", a three-million-year-old skeleton that is the most complete fossilized skeleton from the australopithecine era, has shown that they are much more like he corresponding bones of the modern human than like those of the most closely related living primate, the quadrupedal chimpanzee. Lucy's wide, shallow pelvis is actually better suited to bipedal walking than is the rounder, bowl-like pelvis of the modern human, which evolved to form the larger birth canal needed to accommodate the head of a largebrained human infant .By contrast, the bead of Lucy's baby could have been no larger than that of a baby chimpanzee.

    If the small-brained australopithecines were not toolmakers, what evolutionary advantage did they gain by walking upright? One theory is that bipedality evolved in conjunction with the nuclear family: monogamous parents cooperating to care for their offspring. Walking upright permitted the father to use his hands to gather food and carry it to his mate from a distance, allowing the mother to devote more time and energy to nurturing and protecting their children. According to this view, the transition to bipedal walking may have occurred as long as ten million years ago, at the time of the earliest hominids, making it a crucial initiating event in human evolution.

    Some historians contend that conditions in the United States during the Second World War gave rise to a dynamic wartime alliance between trade unions and the African American community, an alliance that advanced the cause of civil rights. They conclude that the postwar demise of this vital alliance constituted a lost opportunity for the civil rights movement that followed the war. Other scholars, however, have portrayed organized labor as defending all along the relatively privileged position of White workers relative to African American workers. Clearly, these two perspectives are not easily reconcilable, but the historical reality is not reducible to one or the other. Unions faced a choice between either maintaining the prewar status quo or promoting a more inclusive approach that sought for all members the right to participate in the internal affairs of unions, access to skilled and high-paying positions within the occupational hierarchy, and protection against management's arbitrary authority in the workplace. While union representatives often voiced this inclusive ideal, in practice unions far more often favored entrenched interests. The accelerating development of the civil rights movement following the Second World War exacerbated the unions' dilemma, forcing trade unionists to confront contradictions in their own practices.

    Many managers are influenced by dangerous myths about pay that lead to counterproductive decisions about how their companies compensate employees. One such myth is that labor rates, the rate per hour paid to workers, are identical with labor costs, the money spent on labor in relation to the productivity of the labor force. This myth leads to the assumption that a company can simply lower its labor costs by cutting wages. But labor costs and labor rates are not in fact the same: one company could pay its workers considerably more than another and yet have lower labor costs if that company's productivity were higher due to the talent of its workforce, the efficiency of its work processes, or other factors. The confusion of costs with rates persists partly because labor rates are a convenient target for managers who want to make an impact on their company's budgets. Because labor rates are highly visible, managers can easily compare their company's rates with those of competitors. Furthermore, labor rates often appear to be a company's most malleable financial variable: cutting wages appears an easier way to control costs than such options as reconfiguring work processes or altering product design.

    The myth that labor rates and labor costs are equivalent is supported by business journalists, who frequently confound the two. For example, prominent business journals often remark on the "high" cost of German labor, citing as evidence the average amount paid to German workers. The myth is also perpetuated by the compensation consulting industry, which has its own incentives to keep such myths alive. First, although some of these consulting firms have recently broadened their practices beyond the area of compensation, their mainstay continues to be advising companies on changing their compensation practices. Suggesting that a company's performance can be improved in some other way than by altering its pay system may be empirically correct but contrary to the consultants' interests. Furthermore, changes to the compensation system may appear to be simpler to implement than changes to other aspects of an organization, so managers are more likely to find such advice from consultants palatable. Finally, to the extant that changes in compensation create new problems, the consultants will continue to have work solving the problems that result from their advice.