With the past, present and future condensed into one year, let’s have a look at just a few events along the way.
On our scale the Earth formed on 1 January.
It all gets off to an eventful start: on 2 January the Earth was hit by a huge body, and our moon formed from the debris. (ref)
Rocks formed on 3 January (ref).
The first oceans formed on about 4 January (ref).
The first life appeared on 20 January (ref).
When our planet is only at 5% of the age it will reach.
In February photosynthesis started. By March this had made the atmosphere oxygen-rich (ref). That was thanks microorganisms such as the ones still creating these stromatolites in Australia today.
By mid-March life had already existed for two months – or about 2 billion years – in the form of nothing more or less than microorganisms such as the cyanobacteria pictured here. (ref)
“Life, in short, just wants to be. But – and here’s an interesting point – for the most part it doesn’t want to be much.” Bill Bryson, A Short History of Nearly Everything (p408)
Party time, at last! Sexual reproduction appeared on about 17 March (ref) bringing some (albeit small-scale) excitement to what paleontologists joking refer to as the ‘boring billions’ of the beginning of life on Earth. Here are some modern day molluscs at it. (We will only see them evolve in a month and a half.) (photo Tim Robinson)
The supercontinent Rodinia assembled in mid-April (ref).
25 April: earliest plants evolve from algae (ref). They went on to colonise land eventually creating scenes such as this illustrating the Devonian period 400 million years ago.
27 April: the Big Freeze! Snowball Earth events during which the Earth’s surface (almost) entirely froze. The debate is open as to whether these boosted the explosion of life that followed shortly after or were caused by the life that already existed – or both! (ref)
30 April: Life explodes! 540 my ago practically all major types of animals that we recognise today started appearing in the fossil record (ref). It’s the start of the Cambrian Explosion and the end of what palaeontologists joking call the ‘boring billions’ when life was still pretty simple. Here is a reconstitution of Opabinia – a 5-eyed creature that was different from anything seen before in the fossil record. (Image Nobu Tamura).
1 May: welcome crustaceans, gastropods, cephalopods and bivalves! (ref) Here’s a modern day gastropod, a finger plough shell on the west coast of South Africa. (photo Tim Robinson)
By 2 May numerous species of fish had appeared! (ref) Here’s a photo of a shoal of modern-day ‘saupe’ (a kind of sea-bream) on the coast of Provence, France. (photo Tim Robinson)
3 May: the first of the “big five” major mass extinction events in Earth’s history – the Late Ordovician mass extinction 450-440 my ago. Nearly 85% of marine species were eliminated. And fish had only just appeared! The image shows what life might have been like before this extinction. Almost all the action was in the sea: only simple plants had made it onto land by then. (Image: Fritz Geller-Grimm) (ref)
4 May: colonisation of land by plants and insects is underway! And this is only a day after the first mass extinction (a few tens of millions of years in real time). (ref) Here is an ant from KwaZulu-Natal, South Africa. (photo Tim Robinson)
We’re getting closer, but when do you think we’ll get to today on this timeline? Enter your answer here and see how close you are!
5 May: Amphibians appear and soon move onto dry land where they feast on insects without any competition. (ref) Here’s a bucket of migrating toads that I helped cross a road in Brussels, Belgium. (photo Tim Robinson)
6 May: Earth’s second mass extinction – the Late Devonian Extinction of 370 million years ago. 19% of all families or life forms and 50% of all genera became extinct. (ref) The image (by Nobu Tamura) is a reconstruction of Tiktaalik, an early air-breathing vertebrate which died out.
7 May: reptiles appear in the forests that now cover much of Earth’s dry land. (ref forest – ref reptiles) Below is a modern-day but ancient forest on the west cost of Canada plus an ancient type of reptile still with us today – this one in South Africa.
(photos Tim Robinson)
8 May: flying insects (ref) are common in the skies above the super continent Pangea (ref). Below is a reconstruction of Earth 310 million years ago: Laurussia has fused with Gondwana to form Pangea (image Kent G. Budge, CC0, via Wikimedia Commons). Plus a swarm of locusts in South Africa (photo Tim Robinson)
9 May: ‘the great dying’, the Permian–Triassic extinction 251 my ago (ref). Earth’s third and most severe extinction to date, seeing off up to 96% of all species, and over 50% of all families of living things. (Personal note: I won’t take it personally that this is also my birthday 😉 ) Everything that has existed since the Permian-Triassic Extinction evolved from the 4% of species that survived. (Images: Julio Lacerda)
10 May: dinosaurs appear (ref) 240-230 million years ago during the Triassic period. That’s only a week before humans evolve! And some of their descendants – birds – are still with us today, such as this ostrich and his chicks in South Africa (photo Tim Robinson). Very like velociraptors – fast, aggressive and armed with impressive claws!
11 May: The 4th of the Big 5 extinctions! Triassic-Jurassic extinction 201 my ago, profoundly affecting life on land and in the oceans. Among the survivors were dinosaurs and pterosaurs, that on this calendar had only appeared the day before! Amphibians such as this Mastodonsaurus were among the major amphibian groups that went extinct. (Image: Ghedoghedo, CC BY-SA 3.0 via Wikimedia Commons)
13 May: the first mammals and birds appear. The first mammals (ref) were small nocturnal insectivores with a shrew-like appearance, like this Juramaia Sinensis, the oldest known Eutherian (160 my ago). The second is Archaeopteryx (150 my ago), often held to be the missing link between dinosaurs and birds. (ref) (Images Nobu Tamura)
14 May: flowering plants bring colour to dry land, taking advantage of insects and other animals for pollination and seed dispersal. Here are examples from Provence, France. (photos Tim Robinson)
15 May: WHAM! Cretaceous–Paleogene extinction event 66 my ago. 3/4 of plant & animal species disappear! Nearly all four-legged animals over 25kg perish, notably non-avian dinosaurs. (ref) On this calendar they had only appeared 4 days before.
16 May: at around tea time the first apes appear (ref). Modern humans evolve 13 minutes before midnight (that’s 300,000 years in real time).
NOW – midnight 17 May
On this monthly scale there isn’t room to see everything that happened between humans appearing and now, the first moments of 17 May. You need to zoom in to see more detail. So what happens next?
19 May: plate tectonics continues and Africa has pushed so far north that it has joined with Europe. Animals including people are able to walk freely from one to the other. What will ‘immigration’ mean then? (Image from TechInsider – Christopher Scotese)
24 May: the Sun is brighter as it expands, the Moon is smaller in the sky as it moves away from us, and due to the gradual slowing down of Earth’s rotation, each day lasts 25 hours. (Photo Tim Robinson)
By 25 May a new supercontinent forms. This is referred to variously as ‘Pangaea Proxima’, ‘Amasia’, ‘Novopangaea’ and ‘Aurica’ (ref). (Image illustrating Novopangea in 200my by D1221344)
3 June: As the Sun grows brighter and water evaporates from the Earth’s surface, rocks harden, causing plate tectonics to slow. With less volcanism to recycle carbon into the Earth’s atmosphere carbon dioxide levels will fall to the point at which C3 photosynthesis is no longer possible. All plants that utilize C3 photosynthesis (>95% of present-day species) will die. This is in 500-600 million years from now. (ref)
By 20 June the Sun’s luminosity has increased by 10%, causing Earth’s surface temperatures to reach an average of around 47°C (compared to 14°C today). The runaway evaporation of the oceans causes plate tectonics to stop completely. Carbon dioxide levels are so low that C4 photosynthesis stops and all remaining plants and hence animals die out. The only life left on Earth is single-celled organisms. This is in 1.1 billion years from now. (ref).
By the end of June all multicellular life on Earth ceases as the Sun’s habitable zone will move outside the Earth’s orbit (ref).
On this calendar that’s in 6 weeks. A whole lot less worrying when we count that as 1,400,000,000 years from now.
At the end of July the Andromeda galaxy is clearly visible in the night sky as it approaches our Milky Way. But there are no complex forms of life left to see it! All oceans have evaporated and the surface temperature is around 100°C. That’s in 2,300,000,000 years from now. (ref)
In August the Earth’s temperature is 150°C and the only remaining life – bacteria and archaea (prokaryotes) – become extinct. The Earth’s axis becomes increasingly unstable as the moon is more and more distant. (ref)
At the end of December the 12 billion year old Earth is absorbed by the red giant Sun (ref).
It’s hard to see where we fit on this monthly calendar.
Let’s zoom in and see what we find.