A century ago radio was a novel concept. The world is presently in an interglacial period of an ice age which has been on-going for at least about 100 millennia. Recorded history stretches back of order ten millennia, to roughly the point where the present ice age (which stretches back at least about a hundred millennia) entered its present interglacial phase (i.e. one in which only the North polar sea and the South polar continent are ice-locked). The duration of such inter-glacial interludes is generally of order ten millennia.
- 575 to 97 yr ago: superstitious law courts
1431, May 30, Rouen, France: Jean d'Arc burned at the stake for communing with spirits; April 1909, the same maid of Orleans was canonised on grounds of those spirits being deemed angelic.
- 479 to 377 yr ago: John Dee
- A curious fellow, at least partially the inspiration for various figures in literature, from magicians to the secret agent 007.
- 1.696 k yr ago: conversion of Constantine
- The official date, 312 AD, at which the Roman Empire switched from oppressing christianity to promoting it.
- 2.055 k yr ago: Caesar crosses the Rubicon
- 49 BC, January 10th, Julius Caesar paused on the banks of the Rubicon, a river formally marking the border between Italy and Gaul, the province to which he'd been sent with his army. Roman law forbade him to bring his army out of his province: he had to return to Rome and present himself to the senate's judgement of how he'd fared in his campaign; but he knew political machinations were afoot by his enemies. If he took his army with him, he broke the law; if he didn't, he was defenceless against ruthless opponents. While he mulled this dilemma, some of his soldiers crossed the river to enjoy music being played by a shepherd on the other side; Caesar took this as his cue to take his army to Rome, thereby starting a civil war.
- 2.27 to 2.152 k yr ago
- The Punic wars; Rome and Carthage fought for dominance of the Mediterranean.
- 2.291 to 2.218 k yr ago: Archimedes
- The nearest the Romans got to making a decisive contribution to mathematics was killing Archimedes on the beach at Syracuse in 212 BC. Archimedes, aside from his prolific contributions to mathematics and physics, invented several machines of war which helped keep the Romans at bay for some years.
- 2.338 k yr ago: Alexandria
- Alexander the Great founded Alexandria, in Egypt, in 332 BC as part of his campaign of conquests. There may well have been an earlier settlment dating back to as much as 3 k yr ago.
- 2.6 to 2.2 k yr ago: the world is a sphere
The Pythagorean school of thought, in the 500s BC, considered the world a sphere; Aristotle (384–322 BC) threw in some supporting evidence; Eratosthenes (276ish–196ish BC) measured its curvature fairly accurately.
- 2.8 to 2.2 k yr ago: the Axial Age
- 800 to 200 BC, a period of major developments in philosophical/religious thinking across several civilisations stretching (at least) from Greece to China.
- 2.781 or 2.759 k yr ago:
- Rome founded: April 21, 753 B.C. according to tradition; archeological evidence suggests c. 775 B.C.
- 2.82 k yr ago
- Carthage founded by Phoenician settlers fleeing from the political turmoil in the city of Tyre. (814 or 813 BC, according to a not necessarily reliable source.)
- 3.7 to 3.4 k yr ago: the Aegean Bronze age
radiocarbon dating puts the volcanic eruption at Santorini, which heralded the age, between 1660 and 1613 BC.
- 4 k yr ago: Banking
The Akkadian karrum (literally
quay
but meaningmarket
and the traders associated therewith) of Ashur (later: Assyria) controlled trade, levying taxes, keeping its own warehouses and offering warehouse space to merchants; but also holding goods and money on behalf of private merchants and, thus, functioning as abank of deposit
.- 4.55 k yr ago: the Great Pyramid
Built for the pharoah Cheops, a.k.a. Khufu, and still not fully explored – but Dr. Zahi Hawass is working on it.
- 2 to 5 k yr ago
The most recent common ancestor of all currently living humans is estimated to have lived between two and five millennia ago.
- 5.5 k yr ago: Uruk
- Home city of Gilgamesh (and writing, perhaps).
- 6 to 4 k yr ago: civilization emerges
- climate change forced people to live together; and the ones who could cope with that became civilized (i.e. began living together in cities).
- 8 or 4.5 k yr ago
- Ancient chinese writing.
- 11.5 to 8 k yr ago
The Neolithic era, a.k.a. new stone age. People began living in relatively permanent villages and domesticating crops and (other) animals. Archeologists have found buildings from as much as 11 k yr ago.
- 9.4 to 7.7 k yr ago
Çatalhöyük (Çatal = fork (in a path), höyük = mound), in Anatolia, was inhabited, moving from the large mound to the small mound around 8 k yr ago, with a population fluctuating from 3 to 8 k.
- 9.5 k yr ago
Oldest archeological evidence of cats and humans cohabiting.
- 12 to 11 k yr ago
Evidence of early neolithic agriculture: a variety of fig prospering, that normally wouldn't survive, as it needs human intervention to propagate it from cuttings. Note, also, 15 k yr ago, Korean evidence for cultivated rice.
- 12 k yr ago
First successful human settlements in the British Isles.
- 10ish k yr ago onwards: the
Holocene
era - 12.9 k yr ago
- Comet impact maybe provoked climate change and disrupted ecologies in the norther hemisphere.
- 5 to 15 k yr ago
If we look at the set of ancestors of each human alive today, as a function of time, going backwards, there must come a point at which these sets are all identical, known as the identical ancestors point; this is estimated to be between five and fifteen millennia ago.
- 35 to 24 k yr ago
- The end of the Neanderthals
- 40 to 10 k yr ago: upper Paleolithic
The first European humans were already painting erotic pictures 40 k yr ago.
- 39 k yr ago
- Heinrich event 4, a 2 k yr period of sluggish circulation and falling temperatures in the Atlantic, associated with a desert period in Iberia at the end of the Neanderthals' era.
- 45 to 42 k yr ago
Modern humans in Russia.
- c. 50 k yr ago
Modern humans in Australia.
- c. 60 k yr ago
Estimated date of the patrilineal most recent common ancestor of all currently living humans, a.k.a. the Y-chromosomal Adam, based on study of the Y chromosomes of men from around the world.
- 70 to 75 k yr ago
Supervolcano on Sumatra explodes (creating lake Toba), possibly forcing the human gene-pool through a bottleneck, down to between one and ten thousand breeding pairs.
A third of a million years is about the same fraction of the Sun's life expectancy (tenish giga years) as the fraction a day is of a life-span of 80ish years.
You run and you run to catch up with The Sun – but it's sinking,
rushing around to come up behind you again.The Sun is the same, in a relative way, but you're older;
shorter of breath and one day closer to death.Pink Floyd
- 0.13 M yr ago
Ancestors of modern domestic cats diverge from those of their surviving wild relatives; they may have been living with humans all that time.
- 0.14 M yr ago
estimated date of the matrilineal most recent common ancestor of all humans, a.k.a. the Mitochondrial Eve, inferred from study of diversity in human mitochondrial DNA.
- 0.16 M yr ago
Fossils of modern humans (H.Sap.) in East Africa's Rift Valley have been dated to 0.16 M yr ago; our species is believed to have arisen 0.2 M yr ago in sub-saharan Africa, and to have migrated out of Africa – in small groups as early as 90 k yr ago and in significantly larger numbers from around 50 k yr ago.
- 0.4 to 0.2 M yr ago
Separation of Britain from mainland Europe. The North Sea was previously land-locked, but broke out through what is now The Channel, possibly in a single day, gouging a deep trench valley in the process.
- 0.7 to 0.5 M yr ago
Earliest human (or hominid ?) attempts at colonising the British Isles.
- 6.3 to 5 M yr ago
Last common ancestors of chimps and humans.
- 41 to 34 M yr ago
Antarctica and South America separated, allowing an ocean current to circulate round Antarctica, via the Drake Passage, with major impact on Earth's climate – including Antarctica's glaciation.
- 40 M yr ago
Early primates with a mutation began to see red – the origin of colour vision.
- 65 M yr ago
Meteor strike in Yucatan, leaving the Chicxulub crater; dinosaurs died out in the aftermath.
The universe appears to be about 13.7 G yr old; our solar system formed four to five G yr ago and the third major planet (our home, Earth) from its star (The Sun) has teemed with life for much of the time since, acquiring its oxygen-rich atmosphere around 2 G yr ago. The Sun is expected to survive for about another four or five G yr.
- 0.1 G yr ago
Australia split off from Gondwanaland, after a slow splitting-up along a rift valley. The oldest known amber-fossil of a bee dates from about the same time.
- 0.168 to 0.14 G yr ago: Origin of the ants
subsequently diversifying around 100 M yr ago,
in concert with the flowering plants
.- 0.25 G yr ago
The Permian-Triassic mass-extinction, possibly caused by a meteor strike; the resulting crater, lurking under Antarctic ice, is about 480 km (300 miles) wide. This is also roughly when Gondwanaland began breaking up, possibly also thanks to that meteor.
- 0.45 G yr ago
A mass-extinction wiped out plenty of life on Earth.
- 0.85 to 0.544 G yr ago
The Cryogenian era, including 0.2 G yr of
the Neoproterozoic era
. The period is known to have seen extensive glaciation, reaching even to the tropics, but (at least) the era is believed to have seen interglacial warmings.- 0.8 G yr ago
Odd changes happened to ocean chemistry, possibly caused by a
true polar wander
incident – the Earth realigning itself around its spin axis in the space of a few million years.- 2.7 to 2.3 G yr ago: Oxygen atmosphere
cyanobacteria (a.k.a. blue-green algae) showed up somewhat earlier, but at this point their environmental pollution became a major part of the atmosphere. It might be arguable that the damage took a few more mega years to entrench itself.
- 3.4 G yr ago: Early life
Stomatolites in Pilbara, Western Australia, are 3.4 G yr old and some experts maintain that their origin is biological.
- 3.9 to 3.75 G yr ago: Oldest rocks
Rocks as old as 3.75 G yr can be found in the Hudson Bay area of Canada and in West Greenland. The Hudson Bay rocks reveal high levels of CO2 in the atmosphere at a time when the Sun is believed to have been about 25% less bright than it is today; without the CO2, oceans would have frozen. Rocks allegedly formed earlier, as much as 3.9 G yr ago.
- 4.6 or 4.5 G yr ago
Formation of Earth and Moon. Meanwhile, a collision in the Kuiper built broke up 2003 EL61 (which might otherwise have been bigger than Pluto).
- 4.56 G yr ago: Iapetus formed
- Saturn's moon Iapetus has a ridge round its equator; one theory to explain this involves it forming quite early in the Solar System's history.
- 13.7 G yr ago: The Big Bang
Close study of the cosmic microwave background reveals that the universe is 13.7 gigayears old. The first few gigayears were dominated by an initial explosion and the progression of phases through which the results expanded and cooled; so I describe them below in terms of time after that initial explosion.
