The Tethys Ocean finally evaporated, literally, at the Miocene’s end, and it was a spectacular exit. As part of the collision of Africa and Europe, Morocco and Spain smashed together and separated the Atlantic Ocean from the Mediterranean Sea. Then the entire Mediterranean dried out, as there was not enough regional precipitation to replenish the evaporation. Then the crashing Atlantic waves eroded through the rock and the Atlantic again filled the Mediterranean Sea in floods that may have been Earth history's most spectacular. The grinding continents then made another rock dam, the Atlantic was cut off again, and the Mediterranean once again dried up. That pattern happened more than 40 times between about 5.8 and 5.2 mya. Each drying episode, after the rock dam again separated the Atlantic from the Mediterranean, took about a thousand years and left about 70 meters of salt on the floor of the then Mediterranean Desert. The repeated episodes created 2,000-to-3,000-meter-thick sediments of , which is formed from evaporating oceans, as trapped as the Mediterranean was. Creating so much gypsum partially desalinated Earth’s oceans (a 6% lowering), raised their freezing point, and may have contributed to the growth of Antarctica’s ice sheets. Also, those drying episodes initiated great droughts in Africa and may well have spurred the evolutionary events that led to humans.
The (c. 5.3 to 2.6 mya) began warmer than , but was the prelude to today’s ice age, as temperatures steadily declined. An epoch of less than three million years reflects human interest in the recent past. Geologically and climatically, there was little noteworthy about the Pliocene (although the was created then), although two related events made for one of the most interesting evolutionary events yet studied. South America kept moving northward, and the currents that once in the Tethyan heyday were finally closed. The gap between North America and South America began to close about 3.5 mya, and by 2.7 mya the current land bridge had developed. Around three mya, the began, when fauna from each continent could raft or swim to the other side. South America had been isolated for 60 million years and only received the stray migrant, such as rodents and New World monkeys. North America, however, received repeated invasions from Asia and had exchanges with Europe and Greenland. North America also had much more diverse biomes than South America's, even though it had nothing like the Amazon rainforest. The ending of South America’s isolation provided the closest thing to a controlled experiment that paleobiologists would ever have. South America's fauna was devastated, far worse than European and African fauna were when Asia finally connected with them. More than 80% of all South American mammalian families and genera existing before the Oligocene were extinct by the Pleistocene. Proboscideans continued their spectacular success after leaving Africa, and species inhabited the warm, moist Amazonian biome, as well as the Andean mountainous terrain and pampas. The also invaded and thrived as a mixed feeder, grazing or browsing as conditions permitted. In came cats, dogs, camels (which became the ), horses, pigs, rabbits, raccoons, squirrels, deer, bears, tapirs, and others. They displaced virtually all species inhabiting the same niches on the South American side. All large South American predators were driven to extinction, as well as almost all browsers and grazers of the grasslands. The South American animals that migrated northward and survived in North America were almost always those that inhabited niches that no North American animal did, such as monkeys, (which survived because of their claws), and their small cousins (which survived because of their armor), , and (which survived because of their quills). The opossum was nearly eradicated by North American competition but survived and is the only marsupial that made it to North America and exists today. One large-hoofed herbivore survived: the . The (it weighed one metric ton!) survived for a million years after the interchange. , that , also survived and migrated to North America and lasted about a million years before dying out. In general, North American mammals were , which resulted from evolutionary pressures that South America had less of, in its isolation. They were able to outrun and outthink their South American competitors. South American animals made it past South America, but none of them drove any northern indigenous species of note to extinction.
In the months following, many other homosexual men became infected with the human immunodeficiency virus (HIV), which caused the people of South Africa to consider AIDS a disease that solely infected homosexuals....
Africans have also used the threshold of 2000 as an opportunity to claim anew a legitimate place in world history and to fight for their right to self–representation. While Africa's artistic and literary production now enjoys international acclaim, the continent also offers insights into one of the major issues of the postcolonial era–namely, the redefinition of modernity to accommodate "other" personal, religious, or cultural identities: debates around African Islam, métissage (hybridity), and gender have thus multiplied.
With 60 percent of its population under the age of twenty, Africa has the most youthful population in the world; it is also the fastest growing, due to the region's high fertility ratio (5.5 children per woman). Yet infant mortality also remains very high, with more than one in every five children dying before his/her fifth birthday. Extreme poverty, malnutrition, diseases, and armed conflicts are at the root of these preventable deaths. Twelve million children in sub–Saharan Africa have lost one or both parents to AIDS, which further jeopardizes these orphans' chance of survival. Casualties in a new type of war that involves civilian populations, children have also been recruited as child soldiers—in Sierra Leone, Liberia, Somalia, Sudan, and Uganda most notably. Those wars foster a culture of impunity in which sexual violence is commonly used as a weapon, even against children. It is estimated that in Darfur, one–third of the rape victims among the two million displaced people are children. Rapes, in turn, contribute to the spread of HIV/AIDS.
Along with the disruptions that Europe caused to the world’s people, it was depressingly common how often the natives used the newcomers to conquer their neighbors. Although Spaniards inflicted onto the Western Hemisphere in the 1500s, they often had native assistance. The Aztecs were anything but benevolent rulers; their bloody altar constantly sacrificed prisoners (it was an ), and when that ultimately conquered the Aztecs, his native allies did most of the fighting. Any natives who helped the Spaniards helped depopulate their hemisphere. When the French allied with the Huron, the first thing that the Huron did was . That backfired on the Huron, as their tribe became extinct within 40 years. In Africa and North America, when European slavers came, the natives were often only too happy to sell their neighbors into slavery, and some American tribes made for Europeans before they themselves became extinct. With a , natives almost never realized what the coming of Europeans ultimately meant. With some notable exceptions, such as and , natives could not put aside their differences and try ridding their lands of the invaders, and when some tried, it was already too late. When the British began “settling” the South Pacific, the natives used European weapons to slaughter or or .
The peoples of the African rainforests found life relatively easy, mainly because of the same bounty that kept the gorillas and chimps at home in them, while loser apes were and learned to walk upright. For those reasons, agriculture and civilization came late to the rainforests. Domestication in equatorial Africa was likely not but the result of diffusion from the Fertile Crescent.
The explains plenty, and one reality is that women will always have a genetic investment in their offspring no matter who the fathers are. As civilizations rose and , they all had enhanced reproductive rights (many wives, harems, etc.), and many women found the situation tolerable and even attractive, although there could be coercion in the unions and there are many obvious disadvantages to being a "kept" woman. However, being a wife/concubine for an elite man usually meant a pretty good life and children being provided for. The biggest losers in such societies were non-dominant men, who had diminished procreation opportunities (and eunuchs guarded harems, for instance). With the rise of DNA testing, a repeating dynamic is seen: when one people at a higher economic level (energy use) encountered another, the women from the poorer culture bred with the men from the richer culture, and men from the poorer culture began vanishing from the gene pool. It is particularly noticeable among agriculturalist expansions into hunter-gatherer lands, such as the and from the Fertile Crescent into Europe and North Africa, and seems to be implicated in the spread of Mesoamerican farmers into the USA's Southwest. The general pattern during the Neolithic Expansion seems to have been farmers migrating to arable land and establishing agricultural communities that were surrounded by hunter-gatherers, and it seems more common that the farmer populations expanded and displaced (the men)/absorbed (the women) the hunter-gatherer population than hunter-gatherers learned agriculture. After a career of studying human migrations, Peter Bellwood had this to say about what motivated them:
Just as the reason why our may have and why may have , that founder group may well as an act of desperation, driven to the margins by their neighbors. If they left about 60-50 kya, as seems the most likely timeframe in light of today’s evidence, by 10 kya the entire planet had been conquered. Behaviorally modern humans were atop all terrestrial food chains outside of Africa, and in Africa megafauna avoided them, so there was nothing on Earth that threatened human existence except for other humans. Like the way in which the australopithecine Tesla who made the first stone tool the that emerged from his/her act a half-million years later, by 10 kya (about a tenth as long as the previous epochal innovative interval). Several million descendants of that founder group were spread across the planet, from tundra to desert to rainforest, and they filled all inhabitable continents. The people existing 10 kya would have been anatomically recognizable and all had , as they do today. However, with , versus what the founders left Africa with (several million people versus ), the immensely diverse climates and the tools used to survive in them, as well as their mutually unintelligible languages, the founder group’s members would not have comprehended a tour of their descendants’ world. The founder’s descendants even began to look different as evolution marched onward, and many racial differences would have been noticeable, although the bizarre had yet to appear in . Some people of 10 kya even had companions called (first domesticated as long as 33 kya, wolves were domesticated more than once, and the modern dog was domesticated about 15 kya), which would have seemed a miracle, terror, or strange beyond imagining. The world’s large animals paid the ultimate price for fueling that expansion, and the thus began.
As ice sheets retreated and today’s interglacial period began, humans already at the margins of those ice age environments as far as they could. From then until Europe , there were few mass migrations of note, such as the in Africa, when , and when agricultural peoples displaced hunter-gatherers, particularly in Australia and . But even with those migrations, it could be more of a cultural and technological migration than a human one, in which the “invaded” peoples adopted the often energetically superior practices of the “invaders” rather than being replaced by them. Genetic testing has shown that this was (although ), which has been one of the greater surprises of global genetic testing, although the research is in its early days, and more controversial findings are sure to come.