A GLIMPSE INTO THE PLANET THAT EVOLVED WITH US
Professor Lewis Dartnell talks fusing history with science and looking back on how civilisations, the Ice Age and even our origins have all been undeniably influenced by this ball of rock and water we call Earth
What was your inspiration for writing Origins?
With all of my books I’ve written the book I wanted to read but realised didn’t exist yet. It was something that I was really interested in and curious about and I wanted to find out. I took this opportunity to just go off and dig around the subject, do a whole load of research and reading and condense that down to a book for other people.
For my last book, The Knowledge, that all came out of a very simple thought experiment about what would you do to reboot civilisation after an apocalypse. The book has nothing to do with the end of the world; it’s just a way of asking that question of where stuff comes from in our everyday life and how can you recover it all if you wanted to.
What I wanted to do with the new book, Origins, is have an even grander canvas to paint with. Even more so than the history of science and technology, but also look into the history of us as a species and our planet and how those two things have interacted with each other. So it’s a lot of history, a lot of science and a lot of space stuff coming into that as well.
The main aspect of the book talks about the evolution of Earth as much as the evolution of humans, but is there a way we can learn about the evolution of the Solar System from all this as well?
Clearly there are a lot of links from Earth sciences to planetary sciences. I’m a planetary scientist myself; I focus on our next-door neighbour planet, Mars, and a lot of my colleagues who I work with have come from a geology or Earth science background. The knowledge of the processes on Earth – such as volcanism, glaciology or plate tectonics – can be applied to other planets also, whether that is Venus, Mars or the icy moons of Jupiter.
What quite often happens is we find something out about those other planets or moons and apply that knowledge back to Earth, so it completes a full cycle of understanding each other. For example, a lot of research on Venus and the runaway greenhouse effect that it has suffered has been helping us inform scientists on Earth about our own global warming from the carbon dioxide we’re releasing as a species.
I talk about that in Origins
– the problems that have been brought on by global warming currently driven by humans, and how that compares to natural periods of climate change.
Is there a way that humans could have an effect on other planets’ climates, for example if humans went to Mars?
Humanity at the moment as a species – an industrial civilisation – is inadvertently driving climate change on Earth. There are activities that are changing our very environment. People are now talking about doing that deliberately [to other planets] only if we can work out how to do those processes in a controlled way.
There has been talk of doing it to other planets, such as Mars, and this is called ‘terraforming’.
How can you change the environment of Mars to make it more habitable and more hospitable for people to live in? How can you start pumping up its atmosphere? How can you start getting a stronger greenhouse effect on Mars to warm its surface, so that water can flow again? How can you start introducing and producing oxygen on Mars?
People talk about that sort of process being applied deliberately to Mars, so humans – in the far future – can live there.
The beginning of your book talks heavily about plate tectonics. How important are these to life on Earth?
Plate tectonics are one of those fundamental features of Earth as a planetary body. They have been running for billions of years and have had a profound influence on not just the history of human civilisations, but our origin in the first place.
We owe our very existence as an intelligent species to plate tectonics, and a lot of life on Earth owes its existence to plate tectonics and how they help regulate the climate of the entire planet. So one of the big questions for space is which other planets and moons have got plate tectonics on them?
So plate tectonics would be one of the biggest indications for life being able to evolve?
There are other signs of life that you look for, for example bacteria on Mars or bacterium in the oceans of Europa. But in terms of understanding how planets form and change over their lifetimes over billions of years of a planet’s existence, plate tectonics is one of those key fundamental features.
If we’re looking beyond our Solar System at the extrasolar planets [exoplanets], the process of plate tectonics is a key feature to be looking for in a planet to be habitable and host life. People also look for planets orbiting within the habitable zone of their star – the area where the temperature is not too hot and not too cold for liquid water. We would be looking for planets with an appropriate atmosphere; ideally it has a magnetic field to protect the atmosphere and any life from stellar winds and radiation and ideally things like plate tectonics.
How has the orbit of the Earth changed over its lifetime and what effect has that had on Earth?
The Earth orbits within the Sun’s habitable zone. Earth has oceans and had the best possibility for life emerging here. But the Earth’s orbit is not perfectly circular and it’s not static. The Earth’s orbit is constantly shifting, and so is the tilt of Earth’s axis – it gently rocks backwards and forwards ever so slightly. These changes are known as the Milankovitch cycles and they deal with how much the Earth is tilting as well as how egg-shaped or circular Earth’s orbit is. During this time they [Earth’s tilt and orbit] start to fall into step with one another in a particular way that makes parts of the Earth colder, and every now and then they fall out of sync again and the Earth warms back up.
Those Milankovitch cycles have been extremely important for the last two to two-and-a-half million years of Earth’s history because the planet of that period has been on the brink of glaciation; every time those cycles fall into sync with each other the Earth gets tipped into an ice age.
You might expect that in the Ice Age there were these four-kilometre- (2.5-mile) thick sheets of ice grinding their way down from the North Pole.
You’d expect that it would create a very harsh environment for humanity. Indeed it does, but it also gave us, as a species, an incredible opportunity that was very influential in our story.
The Ice Age enabled us to migrate around the entire world. So we evolved in east Africa, as we talked about earlier with plate tectonics, and it was the Ice Age, climate fluctuations and ultimately this cosmic influence – from the Solar System, its planets and Earth’s orbit shift – that lowered the sea levels and enabled humanity to literally walk around the world colonising Asia, down to Australia and more importantly across the Bering land bridge to North America.
How did the night sky, stars and astronomy in general mould civilisations?
Astronomy is one of the oldest sciences. You don’t need any particular equipment to just look up at the sky on a nice, clear, dark night and spot these patterns. We’ve constructed constellations out of these combinations of stars and told stories and legends about them. But ultimately what people were doing was spotting stars that don’t move – the sitting stars that make up the constellations
– and then curiously spotting what appeared to be stars that wandered. They moved through the heavens and they weren’t in the same place night on night or month on month. We now know those to be planets, rocky or gaseous bodies, a bit like the Earth but orbiting the same star as us. Over time we have come to understand what the stars are and how the Sun is also just another star but much closer.
But one of the key functions that stargazing and astronomy have played in our story was in navigation. You can measure the stars and measure the angles between a particular star such as Polaris – the North Pole star – and the horizon, and that will tell you the latitude on the Earth.
As Portuguese sailors were sailing around the west African coast, trying to find a sea route
to India for the spice trade, sometime in the mid-1400s they passed the equator. This wasn’t important just because they were exploring new land, but their system of navigation just broke down. They could no longer see Polaris because they had crossed the equator. Soon after they discovered another constellation in the southern hemisphere – the Southern Cross – that performs a similar function.
I love this story of using the stars to navigate your way across the oceans, to make sure you don’t get lost in this vast expanse and get to where you need to be, but then also working out how to adapt that system when you start going to different parts of the world, like in the Southern Hemisphere, which Europeans hadn’t explored before.
That sort of navigation is a forgotten art now, isn’t it?
We kind of take it for granted now, yes. I’m always getting lost and the first thing I do when I can’t quite work out where I am is reach into my pocket and get out Google Maps on my smartphone. You don’t have to think about navigating anymore, and that’s just over a quarter of a mile!
When you try and imagine what these early navigators were doing, like crossing the entire expanse of the Atlantic or Pacific Ocean, where they had not seen land for weeks upon weeks. Yet they had that confidence that they knew roughly where they were and where they were trying to get to in order to survive the voyage. It boggles my mind just how incredible it is when you think about it.
Now you have looked intensely into the deep history of the Earth, how do you see its future unfolding?
The whole of the book, Origins, is this fusion between history and science. It shows how the human story and the origins of our civilisations have been crafted and influenced by fundamental features of our planet. But then you can use this understanding and knowledge to look into the future, such as how the world is likely to change and how that will affect you and I and our everyday world.
We touched on a similar kind of topic already to do with climate change and how coal and oil was this wonderful resource to get us through the industrial revolution. This has led to the privileged, relaxed and comfortable lifestyle we have today.
But it has unleashed this genie in a bottle. It has had these unintended consequences of putting too much carbon dioxide into the atmosphere and changing our climate. These are the problems we have to solve in the near future.
So by understanding the processes that I talk about in Origins, and how they affect human history, it will also tell us about our own future as a species and what we’ll have to do for ourselves if we were to live on Mars or elsewhere.
What are your thoughts on the mining of asteroids?
So there’s a whole chapter in Origins about the importance of metals in human history. Clearly we’ve gone through the Bronze Age, the Iron Age and today we’re very much in the Steel Age, the Aluminium Age, if not even the Silicon Age – where we use these non-metals for computers, solar panels and so on. The problem with all those exotic metals is they are quite rare and hard to get at on Earth. There’s a limited supply and they’re hard to recycle from the electronics we use.
Therefore there is a huge demand and potentially a lot of money to be made by going to the asteroids and mining those as well as mining these resources on Earth. If you pick the right asteroid, this one lump of rock just a couple of kilometres across could be worth trillions upon trillion of pounds on the global market for different metal.
“We’ve constructed constellations out of these combinations of stars and told stories and legends about them”