IX. LIFE IN “OUR TIME” (3-0 mya)
Australopithecines, (popularly "ape-men"), appeared 3 million years ago. Modern stone-age humans, consisting of the Neanderthals, Homo sapiens, Denisovians, and other eastern races, evolved from these hominids around 200,000 years ago. About 30,000 years ago, North America and Australia were populated from the Asian part of Pangaea (still separating today), via land bridges. The ice caps of the most recent ice chron began to recede about 12,500 years ago, ushering in a warm “interglacial” chron that allowed the development of agricultural and historical culture for humanity. The human population may have been as few as 200,000 at this time.
The development of agriculture created food surpluses that freed humans from hunting and gathering subsistence for the first time, allowing a division of labour, and social hierarchy that led to “civilization”. Civilization is defined by anthropologists as the development of written language, but it also includes the development of religious, political and economic gangsterism, that persists to the present day. The first four civilizations appeared 5000 to 3000 years ago (along the lower banks of major rivers in China, India, Mesopotamia, and Egypt). Independently, civilizations appeared much later (in the christian era) in Central America and in Peru.
During the Pleistocene, large mammals existed, eg. mastodon, sabre-toothed tiger, large galloping rhinoceros (unicorn), large wolves, aurochs and other quadrupeds. As the warm interglacial began, human exploration expanded, and may have resulted in the slaughter of these large animals to extinction. The last individual of these, the Auroch, or ancient cattle, extended into modern times (early 1600’s). Its horns are preserved in a Stockholm museum.
Today, industrial activities are significantly affecting the earth’s biological environment. Artificially manufactured heavy chemicals, radioactivity, and pesticides are threatening to eliminate species links in bio-networks; over-exploitation and widespread destruction of natural habitats are decimating natural species; bio-engineering and genetic modifications to viruses, plant and animal DNA may create unexpected circumstances.
It is already a realistic ecological threat for humans to control or significantly affect weather or climate.
It is now technically possible for humans to make new colonies under the sea, land, in space or on near planetary bodies.
The advent and development of computer-based artificial intelligence offers the prospects of both future dangers as well as hope for controlling the abuses of human social mismanagement.
The activities of 8 billion people on the surface of the planet have become so significant that some have suggested a new geological age should be named: the Anthropocene, perhaps starting with atomic warfare in 1945. However, a geological age is measured in millions of years, and it remains for future generations to discover if an anthropocene age materializes. Thus far, humankind's significant effects on earth's environments are more in the nature of an initializing event.