Major Time Periods
(years before present) |
Years Before Present |
Milestones |
Events |
 |
13.7b ± 200m |
Time,
The Universe |
"This is an interesting time to be a cosmologist," Carroll said. "We are both blessed and cursed. It's a golden age, but the problem is that the model we have of the universe makes no sense." — Nancy Atkinson, quoting physicist Sean Carroll. Universe Today
Mapping of the cosmic microwave background radiation reveals the age of the Universe with unprecedented accuracy. Space.com |
| 13.6b ± 800m |
Milky Way Galaxy |
The Milky Way Galaxy is among the oldest of galaxies, forming within about 200 million years after the Big Bang. — European
Southern Observatory, Milky Way's Age Narrowed Down: Space.com |
| Hadean Time (4560m - 3800m) |
Cryptic Era (4570m - 4150m) |
4570m |
Sun,
Solar System, Earth |
 Solar System, including the Sun and Earth, forms. — European
Southern Observatory |
| 4533m |
Moon,
Seasons |
Planet Theia destroyed in collision with Earth. Large portion
of Earth's crust ejected to form the Moon. The collision may have caused Earth's axis
to tilt, originating the seasons, and may have changed Earth's rotational period,
starting plate tectonics in motion. — Wikipedia: History Of
Earth |
| 4404m |
Minerals,
Water |
 Oldest known mineral (Zircon). Composition of the oxygen isotope in the oldest known zircons suggests that water may have existed on Earth more than 4.4b years ago. — Wikipedia: Zircon |
| Basin Groups Era (4150m - 3920m) |
4000m |
Life |
Origin of life on Earth. — Live
Science |
| Nectarian Era (3920 - 3850 |
3950m - 3850m |
|
The Nectarian Era is named for a large Lunar basin, Mare Nectaris, created by a bombardment of large objects. The effect on Earth of collisions with the same cloud of objects must have been considerable. It is proposed "that these objects were derived from the breakup of one or more large planetoids in the asteroid belt, a result of tidal stresses caused by a close approach to Jupiter, or during the outward migration of Saturn." — Palaeos Hadean: The Nectarian Era |
| Archean Eon (3800m - 2500m) |
Eoarchean Era (3800 to 3600m) |
3800m |
Rocks |
The Isua greenstone belt in southwestern Greenland contains the oldest known well preserved rocks on Earth. — Wikipedia: Isua Greenstone Belt |
| Paleo-Archean Era (3600 to 3200m) |
3600m |
Vaalbara |
Theoretical first supercontinent Vaalbara is believed to have existed 3.3 billion years ago, and possibly as far back as 3.6 billion years ago. Vaalbara may have lasted until about 2.8 billion years ago. — NationMaster: Vaalbara |
| 3600m |
Bacteria |
Oldest known bacteria. — Wikipedia: Precambrian |
| Meso-Archean Era (3200m - 2800m) |
|
|
|
| Neo-Archean Era (2800 to 2500m) |
2500m |
Solar Power,
Rust |
Nature invents photosynthesis, producing oxygen and oxidizing
exposed metals. Most life destroyed by poisonous oxygen gas. — Wikipedia: Oxygen
Catastrophe, New World Encyclopedia: Photosynthesis |
| Proterozoic Eon (2500m - 630m) |
Paleo-proterozoic Era (2800m - 1800m) |
2000m |
Cells |
The three domains of life are established, represented by precursor cells of the fungi,
plants, and animals. Symbiotic relationships between primitive
cells and bacteria originate mitochondria (in animal cells) and chloroplasts
(in plant cells) and perhaps other organelles. — Wikipedia: History Of
Earth — Tree Of Life Web
Project: Eukaryotes |
| Meso-proterozoic Era (1800m - 1200m) |
|
|
|
| Neo-proterozoic Era (1200m - 630m) |
1000m |
Rodinia |
Formation of supercontinent Rodinia including most of Earth's
land mass. — Wikipedia:
Precambrian |
| 1000m |
Plants |
Multicellular plants. — Wikipedia: History Of
Earth |
| 900m |
Animals |
Multicellular animals. — Wikipedia: History Of
Earth |
| 770m |
|
Glaciers may have covered the entire Earth, freezing the oceans (770m
to 600m). — Wikipedia: History Of
Earth |
| Phanerozoic Eon (630m - present)
—
Paleozoic Era (630m - 254m) |
Cambrian Period (630m - 496m) |
600m |
|
Rodinia breaks apart. — Wikipedia: Precambrian |
| 600m |
|
Oldest known complex life forms. — Wikipedia: Precambrian |
| 600m |
|
Global warming caused by carbon dioxide emissions from volcanoes ends
glaciation period. — Wikipedia: History Of
Earth |
| 600m |
Pannotia |
Supercontinent of Pannotia forms. — Wikipedia: History Of
Earth |
| 550m |
|
Pannotia breaks up. — Wikipedia: History Of
Earth |
| 530m |
Backbones,
Fish |
Oldest known vertebrate is a fish from China. — ABC News |
| Ordovician Period (496m - 446m) |
440m |
|
Possible ice ages, more extinction events. — Wikipedia: History Of
Earth |
| 450m |
Arthropods Live On Land |
First arthropods (relatives of insects, arachnids, and
crustaceans) live on land. — Wikipedia: History Of
Earth |
| 488m |
|
Major extinction event. — Wikipedia: History Of
Earth |
| 480m |
Skulls |
First animals with skulls. — Tree Of Life Web Project:
Craniata |
| Silurian Period (446m - 419m) |
446m - 419m |
|
Earth's climate becomes relatively more stable during the Silurian period, large glacial formations melt, and sea level rises substantially. Coral reefs, freshwater fish, and fish with jaws first appear. — UCMP (University of California Museum of Paleontology): The Silurian |
| Devonian Period (419m - 375m) |
405m |
|
Common ancestor of modern fishes and land vertebrates, Osteichtheyes. — LiveScience |
| 400m |
Spiders |
Oldest known spiders. — BBC News |
| 375m |
Fish Move Onto Land |
Discovery of the fossil creature Tiktaalik roseae reveals a link between ancestral fish and land creatures.. — Times
Online New York Times, Tree Of Life Web Project:
Craniata |
| Carboniferous Period (375m - 304m) |
365m |
|
Extinction event. — Wikipedia: History Of
Earth |
| 365m |
Seeds |
Plants evolve seeds. — Wikipedia: History Of
Earth |
| 363m |
Reptiles |
First reptiles. — Tree Of Life Web Project:
Chordata |
| Permian Period (304m - 254m) |
300m |
Pangaea |
Supercontinent of Pangaea forms. — Wikipedia: History Of
Earth |
| Phanerozoic Eon (630m - present)
—
Mesozoic Era (254m - 71m) |
Triassic Period (254m - 204m) |
250m |
Australia |
The impact of the Wilkes Land meteor creates Australia, begins breakup of
Pangaea, and causes extinction of almost all life on Earth. — News24.
The Siberian Traps eruption is an alternative explanation of the
extinctions. — Wikipedia: Siberian
Traps |
| 230m |
Dinosaurs,
Mammals |
The first dinosaurs, mammal-like repriles, and some small mammals descended from the mammal-like reptiles. — Wikipedia: History Of
Earth |
| 210m |
|
Extinction event. The Sixth
Extinction |
| Jurassic Period (204m - 151m) |
180m |
Laurasia, Gondwana |
Pangaea begins to separate into Laurasia and Gondwana. — Wikipedia: History Of
Earth |
| 180m |
Modern Continents |
Laurasia and Gondwana begin to break up, forming the modern continents – a
gradual process that continues today. — International Institute for
Geo-Information Science and Earth Observation |
| Cretaceous Period (151m - 71m) |
150m |
Birds |
Archaeopteryx, the first bird, was an airborne dinosaur, and its descendants are the birds of today, making birds the living relatives of dinosaurs. — Wikipedia: History Of
Earth |
| 140m |
Ants |
Ants. — News.com.au |
| 95m |
|
Isisfordia, ancestor of crocodiles, evolves in Gondwana. — ABC News |
| Phanerozoic Eon (630m - present)
—
Cenozoic Era (71m - present)
—
Paleogene Period (71m - 28m) |
Paleocene Epoch (71m - 59m) |
68m |
  About 68m to 65m years ago, Tyrannosaurus rex and Triceratops inhabited territory that eventually became North America . — Wikipedia: Tyrannosaurus |
| 65m |
End of the Dinosaurs |
An extinction event, the nature of which is unclear, wipes out about 60% of all species, including the dinosaurs. UC Berkeley: The Great Mystery |
| Eocene Epoch (59m - 37m) |
50m |
Whales |
The earliest whales are about 50m years old. They descended from a small land creature, Indohyus, that resembled a deer without antlers. These earliest whales "looked like a cross between a pig and a dog". "They lost their legs and their ability to walk on land by about 40m years ago." — ABC News |
| Oligocene Epoch (37m - 28m) |
29m |
|
Aegyptopithecus Zeuxis, a common ancestor of humans, monkeys, and apes, had a brain the size of a pea. — LiveScience |
| Phanerozoic Eon (630m - present)
—
Cenozoic Era (71m - present)
—
Neogene Period (28m - present) |
Miocene Epoch (28m - 7.2m) |
22m |
Apes |
Apes happen. — Primates.com |
| 10m |
|
Apes and human ancestors may have become differentiated as long ago as 10m years. — Breitbart.com |
| Pliocene Epoch (7.2 - 3.6) |
4.4m |
Bipedality |
Some apes begin to walk upright. — University
Of Texas |
| 4m |
|
Earliest known Australopithecus. — LiveScience |
| 4m |
Laughter |
Apes invent slapstick humor. — Times
Online |
| Pleistocene Epoch (3.6m - 12,600) |
2m |
Genus Homo |
Apes of genus Homo, ancestors to humans. — Wikipedia: History Of
Earth |
| 1m |
Wolves,
Coyotes |
Wolves and coyotes diverge from common ancestor. — Wayne,
Robert K, et. al - Science Magazine |
| 790,000 |
Fire,
Thinking |
Homo erectus learns to use fire. — Wikipedia: History Of
Earth.
Homo erectus was probably the earliest human ancestor that posessed the brain structures required for complex planning, calculation, and abstract thought. — Glynn, 1999 - An Anatomy of Thought |
| 600,000 |
|
First ice age (600,000 to 540,000 years ago) — The
Penguin Atlas of World History : Volume 1 |
| 540,000 |
|
First Interglacial Period (540,000 to 480,000 years
ago) — The
Penguin Atlas of World History : Volume 1 |
| 480,000 |
|
Second Ice Age (480,000 to 430,000 years ago) — The
Penguin Atlas of World History : Volume 1 |
| 430,000 |
|
Second (Great) Interglacial Period (430,000 to 240,000 years ago)
— The
Penguin Atlas of World History : Volume 1 |
| 240,000 |
|
Third Ice Age (240,000 to 180,000 years ago) — The
Penguin Atlas of World History : Volume 1 |
| 180,000 |
|
Third Interglacial Period (180,000 to 120,000 years ago) — The
Penguin Atlas of World History : Volume 1 |
| 160,000 |
Humans |
Humans (Homo Sapiens) originate in Africa. — Journey Of Mankind |
| 135,000 |
Dogs |
Dog and wolf species begin to diverge. — Wayne,
Robert K, et. al - Science Magazine |
| 120,000 |
|
Fourth Ice Age (120,000 to 10,000 years ago) — The
Penguin Atlas of World History : Volume 1 |
| 115,000 |
|
Humans populate most of Africa and reach Egypt. — Journey Of Mankind |
| 100,000 |
|
Neanderthals inhabit much of Europe. — UCLA |
| 100,000 |
Ritual |
"Although the first members of Homo are present in the fossil
record 2.5m years ago, the first unambiguous evidence for religious
ritual is only associated with the appearance of anatomically modern humans not
more than 100,000 years ago in terms of what appear to be ritualized burials in
the caves of Skhul and Qafzeh in the East." — (Mithen, 1999)  |
| 100,000 |
Language |
There are many estimates of the time of origin of spoken human
language, and many theories about why and where it first appeared. Most
estimates place the first use of language between 120,000 and 65,000 years ago.
For more information see: National
Virtual Translation Center |
| 100,000 |
Human ancestors become different from all other animals. |
It may be noteworthy that the period from 100,000 to 30,000 years ago
coincides loosely with the development of symbolism, ritual, language, and
spirituality. This time period seems to encompass revolutionary developments in
human brain physiology and accompanying cultural development.
It appears to be
during this time that our ancestors truly became distinguished from all the
other creatures by new developments in their mental capacity. "None of us can
directly experience the consciousness of a nonhuman animal because we cannot
escape the consciousness defined by our use of language (Olson, 2002 p88)." |
| 90,000 |
|
Humans die out in Egypt. — Journey Of Mankind |
| 85,000 |
|
Humans cross the mouth of the Red Sea to reach Arabian Peninsula.
— Journey Of
Mankind |
| 74,000 |
|
Human population reaches Indonesia, then southern China by migrating
along Indian Ocean coastline. — Journey Of Mankind |
| 74,000 |
|
Mt. Toba, in Sumatra, erupts, creating Lake Toba, causing a 6-year
winter followed by a 1000-year ice age and mass extinctions. Worldwide human
population decreases to about 10,000. Probably, no humans survive in India.
— Journey Of
Mankind |
| 65,000 |
|
Humans repopulate India and enter Australia and New Guinea. — Journey Of Mankind |
| 60,000 |
Symbolism, Tradition,
The Supernatural |
The time between 60,000 and 30,000 years ago seems to "mark some form
of threshold in human cognitive development" (Mithen,
1999). Steven Mithen (Professor of Archaeology at the University of Reading) proposes that humans acquired the ability to
coordinate separately-evolved kinds of thought, which he calls "cognitive
domains", involving separate brain structures. The cognitive domains include
thinking about "material objects, living things, and the human social world."
This new ability differs from associative learning, which was already long
established. Called "cognitive fluidity", this new feature created within
humans the ability to use symbols to represent ideas, making it possible to
communicate complex concepts like tradition, tool making, anthropomorphic ideas
about animal behavior, and concepts of the supernatural. It is interesting that
while cognitive fluidity has been generally favorable to survival, some uses of
this ability may be maladaptive. |
| 52,000 |
|
General warming. Humans populate the Fertile Crescent, then Europe.
— Journey Of
Mankind |
| 45,000 |
|
"Mini Ice Age" |
| 40,000 |
|
Various groups of humans expand into Southern, Central, and Northern
China, and into Japan and some Pacific islands. — Journey Of Mankind |
| 28,000 |
|
Last of the Neanderthals. — UCLA |
| 25,000 |
|
Central Asians populate eastern Europe and Siberia. — Journey Of Mankind |
| 22,000 |
|
Asian ancestors of Native Americans cross into Alaska from Siberia,
migrate as far as eastern US (Meadowcroft). — Journey Of Mankind |
| 18,000 |
|
Last Glacial Maximum (during last Ice Age). Most human populations
die out in northern Europe, Siberia, and northern North America, with isolated
enclaves surviving. — Journey Of Mankind |
| 15,000 or earlier |
Domestic dogs |
Earliest archaeological evidence of dogs living with people. Mitochondrial DNA suggests that dogs may have begun to diverge from their wolf ancestors much earlier than this, but still long after wolves began associating with humans or human ancestors. The divergence of the dog from the ancestral wolf line may even be an evolutionary response to living among humans. — About.com: Dog History, Archeaozoology: Origins of the Domestic Dog |
| 15,000 |
|
Native Americans reach northern South America. — Journey Of Mankind |
| Holocene Epoch (12,600 - present) |
12.500 |
|
Ice Age climate moderates. Isolated northern human enclaves expand to
establish Eskimos, Aleuts, and Na-Dene language speaking people. — Journey Of Mankind |
| 10,000 |
Farmers |
End of the Last Ice Age. Humans invent agriculture in the
fertile crescent, re colonize Britain and Scandinavia. — Journey Of Mankind |
| 10,000 |
Blue Eyes |
"Everyone with blue eyes can be traced back 10,000 years to the Black Sea region." — Mail Online |
| 5,000 |
Writing |
Accountants invent written language. — Wikipedia: Writing |
| Anthropocene (proposed, ~200 - present) |
~200 |
Steam Engine |
The term "Anthropocene Period" is proposed by Paul Crutzen, and has found some acceptance. Its name refers to the disproportionate influence of humankind on the climate and ecosystems of Earth. The beginning of the Anthropocene Period is taken to be somewhere around the date of the invention of the steam engine by James Watt in 1784, near the beginning of the industrial revolution. — Wikipedia: Anthropocene |