According to a theory advanced by researcher Paul Martin, the wave of species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans. However, anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demonstrate that Paleoindians hunted them. Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption. Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene. Still, Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians, arguing that humans have produced local extinctions elsewhere. But, according to historian Richard White, even the attribution of secondary responsibility may not be supported by the evidence. White observes that Martin's thesis depends on coinciding dates for the arrival of humans and the decline of large animal species, and Krech, though aware that the dates are controversial, does not challenge them; yet recent archaeological discoveries are providing evidence that the date of human arrival was much earlier than 11,000 years ago.

(This passage was adapted from an article written in 1990.)

    Research data indicate that there is a great deal of poverty in the United States among singleparent families headed by women. This problem could result from the fact that women's wages are only 60 percent of men's. Some economists believe that rigorous enforcement of existing equal pay laws would substantially decrease this wage inequity. But equal pay laws are ineffectual when women and men are concentrated in different occupations because such laws require only that women and men doing the same jobs be paid the same. Since gender concentration exists (for example, 80 percent of clerical workers are women), other economists argue that a comparable worth standard, which would mandate that women and men in any jobs that require comparable training and responsibility be paid the same, should be applied instead. But some policy analysts assert that, although comparable worth would virtually equalize male and female wages, many singleparent families headed by women would remain in poverty because many men earn wages that are below the poverty line. These policy analysts believe that the problem is not caused primarily by wage inequity but rather by low wages coupled with single parenthood, regardless of sex. As a solution, they challenge the government's assumption that a family's income should depend primarily on wages and urge the government to provide generous wage supplements (child and housing allowances) to single parents whose wages are low.

    In Winters v. United States (1908), the Supreme Court held that the right to use waters flowing through or adjacent to the Fort Berthold Indian Reservation was reserved to American Indians by the treaty establishing the reservation. Although this treaty did not mention water rights, the Court ruled that the federal government, when it created thereservation, intended to deal fairly with American Indians by preserving for them the waters without which their lands would have been useless. Later decisions, citing Winters, established that courts can find federal rights to reserve water for particular purposes if (1) the land in question lies within an enclave under exclusive federal jurisdiction, (2) the land has been formally withdrawn from federal public lands — i.e., withdrawn from the stock of federal lands available for private use under federal land use laws — and set aside or reserved, and (3) the circumstances reveal the government intended to reserve water as well as land when establishing the reservation.

    Some American Indian tribes have also established water rights through the courts based on their traditional diversion and use of certain waters prior to the United States' acquisition of sovereignty. For example, the Rio Grande pueblos already existed when the United States acquired sovereignty over New Mexico in 1848. Although they at that time became part of the United States, the pueblo lands never formally constituted a part of federal public lands; in any event, no treaty, statute, or executive order has ever designated or withdrawn the pueblos from public lands as American Indian reservations. This fact, however, has not barred application of the Winters doctrine. What constitutes an American Indian reservation is a question of practice, not of legal definition, and the pueblos have always been treated as reservations by the United States. This pragmatic approach is buttressed by Arizona v. California (1963), wherein the Supreme Court indicated that the manner in which any type of federal reservation is created does not affect the application to it of the Winters doctrine. Therefore, the reserved water rights of Pueblo Indians have priority over other citizens' water rights as of 1848, the year in which pueblos must be considered to have become reservations.