When I started this series of blogs on the history of the Earth, I said that it was a journey that I was happy to travel alone.

However, I am delighted that so many of you chose to join me. Thank you.

And thank you for all your 'likes' and comments. It was extremely encouraging to know that people were enjoying it.

Just in case anyone is interested, today's photograph shows all the books that I used during the course of this series of blogs.

The books are arranged in three categories:

- on the left are the ones upon which I heavily relied.

- the books on the right focus on our present and our future.

- in the middle, are the ones that I dipped into.

And, of course, I made extensive use of Wikipedia, which is – in my opinion – an example of humanity at its absolute best.

If anyone wants my views on any of the books, please leave a comment or message me. I haven't read all of all of them, but I now have a 'feel' for most of them.

From reading these, one thing became abundantly clear; there is so much that we don't know.

If these blogs had been written 10 years ago, they would have been very different. 30 years ago and it would probably have been impossible. If I were to do it again in 10 years' time, many elements will be very different as we make new discoveries.

The books I particularly recommend are:

Bill Bryson, 'A Short History of Nearly Everything' (2003): a work of genius by a genius.

John Hands, 'Cosmosapiens' (2015): a fascinating analysis of human evolution by a maverick thinker.

Guido Tonelli, 'Genesis' (2021): reading it makes you feel more intelligent, even though you don't understand a word of it, or perhaps it is because you don't understand a word of it.

Dave Goulson, 'Silent Earth' (2021): he is just a brilliant writer (and he knows his bumblebees). Anything by Goulson is brilliant.

Thank you. Here endeth my 50th blog in this series.

Oh, actually...

My final – rather banal – thought is this.

If we knew for certain that humanity would still be on this Earth in a million years from now, what decisions should we make today to ensure that the lives of our descendants are as good, or even better, than ours?

Tags:   history historyofearth bibliography books

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In the next 100 million years, we know that Africa will merge with Europe, and Australia with Asia.

We know that the Solar System will complete half an orbit of Sagittarius A*, the black hole at the heart of the Milky Way.

Beyond that, we know nothing.

"I have seen all possible futures," says Paul Atreides in 'Dune: Part 2'.

But, over 100 million years, that's a lot of futures.

So, let's keep it simple.

If there is a 6th extinction event, evolution will respond by filling the gaps. And it will do so in unpredictable ways, as when it unexpectedly chose mammals to inherit the crown of dominance from dinosaurs.

But exactly how evolution fills those gaps may depend on whether humans are still around to mess things up.

So how long can we expect Homo sapiens to be around?

Well, the average lifespan of a mammal species is 1 million years, which gives us potentially 700,000 more years. But, as an adaptable species, we should theoretically live far longer.

But might we go extinct first?

On this, I agree with John Hands in his book 'The Future of Mankind'. There is no realistic scenario in which a single event will render humanity extinct. After all, in the 20th century, our exponential growth was untouched by two World Wars, Spanish Flu, smallpox, genocides and a hundred other conflicts.

Of course, in the next 100 million years, we will experience catastrophes beyond any we have ever experienced. Yellowstone's supervolcano will blow; asteroids will strike; volcanic activity will accompany tectonic collisions. There may even be nuclear war.

But these are unlikely to kill us all.

So, if we are still here in 10, 50, 100 million years' time, how might we have changed?

Well, in a mere 50,000 years, we have progressed from cave-painting to AI, from family groups to the UN; and human consciousness has evolved to encompass abstract thought, reason and imagination.

Are there levels of consciousness beyond this?

Quite possibly.

After all, we consist of atoms that were birthed in supernovae. Together, they briefly combine to form 'us', but, when we are gone, they will continue their journey until the death of the universe. In a sense, each of us is simply a temporary home for eternity. The universe passes through us. We are created from atoms, and to atoms we will return.

Fyodor Dostoyevsky observed that, in the moment before he had an epileptic fit: "I feel full harmony in myself and in the whole world." Those who take the drug psilocybin report similar experiences. Some call it ego dissolution, an experience of merging the self with something bigger.

Perhaps evolution will take us there, to a place where humanity loses its sense of entitlement and superiority.

Maybe, 100 million years from now, humanity will live in equilibrium with the rest of creation.

Maybe, humanity will be a better version of itself.

Maybe.

Who knows, but we can hope.

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It is easy to be negative about the current state of the world.

But, if you were to choose any place and time in Earth's long history in which to live, you would probably choose here and now.

We have a breathable atmosphere, good dentistry, vaccines and antibiotics. Steven Pinker, in his book 'Enlightenment Now', explains in detail why we have never had it so good.

But will it remain that way?

In this series of blogs, each day has covered 100 million years. A minute is 70,000 years; each second is a millennium.

On those timescales, Homo sapiens has been on Earth for just 4 minutes.

Throughout that time, the world has been an icehouse, with icecaps covering the poles. That is the climate that has enabled us to develop agriculture and build cities.

This icehouse has been sustained by atmospheric carbon dioxide at below 300 parts per million (ppm). But now it is at 420ppm, a level not seen for 3 million years, and a 50% increase on pre-industrial levels. And it is rapidly increasing.

Global warming is happening 10 times faster than at any point in the last 66 million years. In 1850, Montana's Glacier National Park had 150 glaciers; now, it has 26.

And this is, of course, because - just 0.25 seconds ago - we started burning fossil fuels.

As we already know, coal largely formed during the Carboniferous. Oil, though, formed over a broader period (mostly between 252mya to 66mya) from decomposed plankton. Gas (a polite word for methane) is a byproduct of oil.

Coal, oil and gas have literally fuelled human progress and expansion in the last two centuries.

And, boy, have we expanded. In 1928, there were 2 billion humans. When I was born in 1967, it was 3.45 billion and now it is 8.1 billion.

This has led to an unbalancing of the planet.

Humans now make up 34% of all mammal biomass. Our domesticated creatures add another 62%, leaving just 4% for the remaining 6,400 species of wild mammal.

Never before has one species so dominated the planet.

And, as a result, environmental change is happening far quicker than in four, and possibly all five, of the great extinctions.

Between 1970 and 2012, the total population of the world's vertebrates dropped by 60%. The UK now has 44 million fewer birds. In North America it is nearly 3 billion.

It is estimated that we use the planet's resources 1.75 times faster than the Earth can regenerate them. For Americans, it is 5.1 times.

This is utterly unsustainable.

And that's why many believe that we are at the beginning of the 6th great extinction event.

At some point, we humans forgot that we are part of the environment, inextricably entwined with the air, the land and the sea.

Of course, the planet will survive. It has seen much worse.

But what about us, as we rapidly create a world that is inhospitable to us?

On this Easter Sunday, it seems entirely appropriate to ask: who will save humanity from itself?

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The second half of the Cretaceous (145mya to 66mya) was a golden period for dinosaurs.

We have such fan favourites as Triceratops, Velociraptor, Ankylosaurus and, of course, Tyrannosaurus rex.

T. Rex appeared 72.7mya, and it was 8.8 tonnes of Pure Anger.

But it wasn't the largest dinosaur. That honour falls to the herbivorous titanosaurs, such as Patagotitan, which were 35m long and 70 tonnes. That's longer than a Blue Whale, and twice the weight of a Brontosaurus.

Meanwhile, flowers spread at such speed that they became the dominant group of plants. You could say they blossomed. Nowadays, they make up around 90% of all plant species. And, unsurprisingly, they co-evolved alongside pollinators, such as bees, butterflies and moths.

The first grasses appear. And we therefore see the first grasshoppers, plus the first ants and aphids.

But then the Cretaceous came to an abrupt end.

The planet was already struggling because of greenhouse gases generated by lava spewing from the Deccan Traps in India.

But, then, around 66mya, the weakened Earth was struck by an asteroid the size of Bristol, creating the Chicxulub crater, 200 kilometres wide and 20 deep, in Yucatan.

In this, the last great Extinction Event, 75% of all species disappeared.

It's weird, isn't it? We think of the dinosaurs as being from 'long ago'. But, in the context of these blogs, they only left us today at breakfast.

Except that they haven't really left us, because birds are dinosaurs, evolving from the theropods, which is the same group as T. Rex. One of my favourite facts is that there are more species of dinosaur alive today than mammals: 11,000 as against a mere 6,400 mammals.

And that brings us onto the Paleogene (66mya to 23mya), the Neogene (23mya to 2.5mya) and the Quaternary (2.5mya to now).

After an extinction event the world is not the same as before. There are environmental niches to be filled and food chains to be recreated. And evolution achieves this by using whatever user-friendly species are around.

And, for the last 66 million years, that has been mammals.

Mammal derives from the Latin 'mamma' meaning breast (as, indeed, might the 'Man' of Mansfield). And it is the mammary gland that is the mammal's USP.

Mammals come in three forms: monotremes that lay eggs, marsupials where babies develop in a pouch, and placentals where they develop inside a womb.

Mammals first appeared around 225mya. They were small inconsequential things. Indeed, they mostly still are: 70% of mammals are rodents, bats or shrews.

But a minority grew large to be mastodons, and sabre-toothed tigers, and woolly rhinoceroses, and elephants. And, around 52mya, mammals even returned to the oceans to become dolphins and whales.

But size isn't everything.

Unless its brain size, of course.

Which brings us to a certain puny, mostly-hairless, but very brainy, mammal...

Tags:   history historyofearth Asian elephant Cretaceous Paleogene Neogene Quarternary

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It's what you've been waiting for. So, please, put your hands together for the only geologic period that has a film franchise - AND a coast - the one and only, JURASSIC!!! (201mya to 145mya)

The Jurassic is, of course, the start of the Age of Dinosaurs. Albeit not the ones in the film. The film should really have been called Late Cretaceous Park.

Anyway, we'll come onto that.

One lesson we learn from Earth's history is that an extinction event is both destructive and creative.

It is destructive for those species that do not survive. Over the aeons, up to 5 billion species have died out. That's 99% of all species that have ever lived.

But, for the survivors, it is party time.

The dinosaurs became carnivores and herbivores, small, medium, large and huge. They even took to the air. The world was now their oyster (which also evolved around this time).

But what is a dinosaur?

It is often used as a generic name for any 'old big dead lizardy thing'. But dinosaurs are, in fact, a specific family with specific characteristics.

What characteristics?

Well, if I show you a cat and a dog, you would immediately be able to tell the difference. But you might struggle to explain that difference to an alien who had never seen either before.

It's the same with dinosaurs.

In the Triassic, there were lots of families called somethingo-saur (where 'saur' means lizard). But their anatomies were all subtly different.

Perhaps the most obvious thing anatomically about dinosaurs is that their legs extend straight down from their body. Dinosaurs therefore stand upright. Contrast that with crocodiles, or modern lizards, whose legs emerge sideways.

Dinosaurs had emerged in the Triassic as bit-part players. However, in the Jurassic, with their competitors wiped out, they dominated, albeit the only box office ones were the giant herbivore Diplodocus, and Allosaurus, the Poundland T Rex.

But dinosaurs were not the only reptiles on planet Earth. Turtles chose this moment to diversify, lizards and snakes went their separate ways on the Tree of Life, and ichthyosaurs and plesiosaurs dominated the seas.

As an aside, the Loch Ness Monster is a plesiosaur, albeit an imaginary one.

On land, new conifers appeared, including cypress and yew. Ginkgos, which had been around since the Permian, formed forests.

And the air space was shared by the reptilian pterodactyl and the bird-like archaeopteryx, so the leather-winged and the feather-winged.

Into the Cretaceous (145mya to 66mya), and it is:

Hello to flowering plants! Around 130mya, the first water lilies appeared. Soon after, flowers were everywhere. Flowers went viral.

And, hello to Stegosaurus, Brontosaurus and Brachiosaurus!

And, hello to birds! Which increasingly looked like modern birds.

And the mammals? Well, they remained small nocturnal timid things.

But their day would come. And it would come soon.

Tags:   historyofearth history Utah Moab dinosaur tracks Jurassic Cretaceous

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