General Scientific Timeline of World History / Pre-History
Adapted from http://en.wikipedia.org/wiki/Timeline_of_evolution (2010) and http://www.talkorigins.org/faqs/homs/species.html (accessed 2010) (each with bibliographies and references too numerous to list here) by MJK.
(Very Approximate Dates, not all sequence implying direct lineage)
4.5 billion year old Earth[1] forms from the accretion disc revolving around the young Sun.
3.8 billion years of simple cells (prokaryotes – no cell nucleus or membrane-bound organelles),
3 billion years of photosynthesis.
2 billion years of complex cells (eukaryotes – w/ a nucleus and usu. organelles like mitochondria),
1 billion years of multicellular life (ex. photosynthesizing cyanobacteria, and others),
600 million years of simple animals (ex. sponges – differentiated cells, but no distinct tissues),
570 million years of arthropods (ancestors of insects, arachnids and crustaceans),
550 million years of complex animals,
500 million years of fish and proto-amphibians,
475 million years of land plants,
360 million years of amphibians,
300 million years of reptiles,
200 million years of mammals,
150 million years of birds,
130 million years of flowers,
6-7 million years ago - Sahelanthropus tchadensis – oldest known hominid or near-hominid species,
4.4 million years ago - Ardipithecus ramidus - chimp-size skull; bipedal on ground, quadrupedal in trees,
3.9 – 3 million years ago - Australopithecus afarensis – brain 375-550 cc. Only in Africa.
3 – 2 million years ago - Australopithecus africanus – brain 420-500 cc. Only in Africa.
2.4 – 1.5 million years ago – Homo habilis – tools, brain 500-800 cc.; 5' tall, 100 lbs.; only in Africa.
1.8 million – 300,000 years ago – Homo erectus - Like habilis, protruding jaws, large molars, no chin, thick brow ridges, long low skull; brain 750 to 1225 cc; more robust than modern humans; maybe efficient at walking than modern humans, whose skeletons have had to adapt to allow for the birth of larger-brained infants; wide-ranging, found in Africa, Asia, and Europe; probably used fire, and their stone tools are more sophisticated than those of habilis.
500,000 years ago – Homo sapiens (archaic) (also Homo heidelbergensis) - Archaic forms of Homo sapiens; skulls with features of both Homo erectus and modern humans; brain avg. 1200 cc, skull more rounded than erectus; skeleton and teeth usually less robust than erectus, but more robust than modern humans; no clear dividing line yet between late erectus and archaic sapiens, and many fossils between 500,000 and 200,000 years ago are difficult to classify as one or the other.
230,000 – 30,000 years ago – Homo sapiens neanderthalensis (also Homo neanderthalensis) – Neanderthal; avg. brain 1450 cc, prob. correlated w/ their greater bulk; brain case longer and lower than modern humans, with a marked bulge at back of skull. Like erectus, a protruding jaw and receding forehead; chin was usually weak; midfacial area protrudes, not found in erectus or sapiens, maybe an adaptation to cold; some peculiarities of shoulder blade and pubic bone; men avg. 5'6"; bones thick and heavy, extraordinarily strong by modern standards; endured brutally hard lives; large number of tools and weapons, more advanced than Homo erectus; formidable hunters; first people known to have buried their dead; found throughout Europe and the Middle East.
100,000 years ago - oldest known burial site (Neanderthal).
94,000 – 13,000 years ago – Homo floresiensis - Indonesian island of Flores; brain 417cc.; thought to be a dwarf form of Homo erectus (not uncommon for dwarf forms of large mammals to evolve on islands).
195,000 years ago – Homo sapiens sapiens (modern) – avg brain 1350 cc; forehead rises sharply, eyebrow ridges very small or usu. absent, chin prominent, and skeleton very gracile.
40,000 years ago – Cro-Magnon culture; tool kits markedly more sophisticated; use of bone and antler; implements for clothing, engraving, sculpting; fine artwork, decorated tools, beads, ivory carvings of humans and animals, clay figurines, musical instruments, cave paintings over the next 20,000 years.
25,000 years since Neanderthals died out.
Long-term trends towards smaller molars and decreased robustness; face, jaw and teeth of Mesolithic humans (about 10,000 years ago) about 10% more robust than ours; Upper Paleolithic humans (about 30,000 years ago) are about 20 to 30% more robust than modern Europe and Asia; interestingly, some modern humans (aboriginal Australians) have tooth sizes more typical of archaic sapiens; smallest tooth sizes are found in those areas where food-processing techniques have been used for the longest time – a probable example of natural selection within the last 10,000 years. Blue eyes, blond hair also within 10,000.
12,500 – 10,000 – 8,000 b.c.e. – Development of Agriculture in Southwest Asia / Middle East.
10,000 – 7,500 b.c.e. – 5,700 – Towns/Cities. ex. Asikli Höyük, Catal Höyük.
c. 7,000 b.c.e. – Nabta Playa stone circle, Egypt.
5,300 b.c.e. – intensive, year-round agriculture in Sumer.
4,100 – 3,100 – Uruk period – emergence of urban life in Mesopotamia.
3,000 b.c.e. or before – full-fledged civilization, with dynasties, empire, class structure, writing ... in Sumer (Mesopotamia) and Egypt.
[1] 4.54 billion -- determined by radiometric age dating of meteorite material and consistent with the ages of the oldest-known terrestrial and lunar samples. http://en.wikipedia.org/wiki/Age_of_the_Earth; Dalrymple, G. Brent (2001). "The age of the Earth in the twentieth century: a problem (mostly) solved." Special Publications, Geological Society of London 190: 205–221. (http://sp.lyellcollection.org/cgi/content/abstract/190/1/205 ). Dalrymple, G. Brent. The Age of the Earth, (Stanford University Press, 1991).