A reflection on our molecular origins

Saturday, July 18th, 2009 | cosmology, history

[IN AUGUST 2008, I was asked to give a talk on climate change in the Rhodes University History Department. This, the department that turned my world view upside down, over a decade ago. Some say science shows us we don't need god. I'd say history did that for me. I grew up believing that god was the beginning and the end, the Alpha and Omega, that human beings were just a small blip on the longer timeline of god. Then I studied history, and discovered that the human timeline was a lot longer than Sunday School lead me to believe… suddenly I realised that god was just a small blip on the much longer and more impressive timeline that is the history of this universe.

Some people figure this out right from the start. I’m a late starter, I’ll admit to that. But at least I get there in the end. So this, a little reflection on why history matters, and why science and history and natural history are inseparable disciplines. An extract from my own little gospel of rational thought.]

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It all starts with a tremendous boom. In a single instant, about 14 billion years ago, all matter and energy are flung out across an expanding universe.

Slowly, the heat from that explosion dissipates. The billowing skirt of the universe is mostly hydrogen and helium. Here and there, this tumbles together to form cosmic clouds. These gas clouds are ignited, switching on the first stars across the heavens. It is in the very heart of these stars that the heavier elements are cooked up, at unimaginable temperatures.

Then boom… each of these stars explodes, scattering the heavens with their remains, which later spin together into new heavenly bodies.

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Much later… 4.6 billion years ago:

Some of that matter – that scattered dust, rubble, space junk – is tugged into orbit around a minor star, which moulds it like putty into a neatly spinning ball. The crust of the infant planet cools and hardens, then cracks, leaking gas out from its hot mantle. Earth is born. But it is lifeless.

Shortly after its birth, an object the size of Mars slams into young Earth, blasting out a chunk of its newly formed crust. Earth’s own gravity in turn spins this into our silent companion, the moon.

As gases escape through its creaking epidermis, Earth’s gravity holds onto them, creating the planet’s first atmosphere. Some of that is water vapour, which condenses into clouds and Earth’s first rains begin to fall. The water gathers into gullies and ditches on its scabrous surface. Eventually, over millions of years, two thirds of Earth becomes enveloped in salty water. Earth remains lifeless, but the first water cycle and geological processes are churning that matter over, all that star stuff that rolled together around the sun to become this spinning ball.

Then, about a billion years later (3.6 billion years ago) the first life forms emerge, either in tidal pools or, more likely, around thermal vents on the ocean floor. Slowly, the ocean is populated with different life forms.

For billions of years, life remains incubated within our oceans, the continents are rocky and barren… but eventually, across a gulf in time (nearly 500 million years ago), a few plants creep up onto land, adapt to breathing in air rather than water, and eventually allow evolution to sculpt land animals to live on the newly colonised continents.

Species rise and fall, growing up out of the nutrient cycle and then collapsing back into it as they become extinct – insects, amphibians, dinosaurs, mammal-like reptiles, birds, mammals… until now, 99 percent of all life that has ever existed has dwindled into extinction. It’s upon the shoulders of their evolutionary work that today’s species can stand.

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Eventually, some of that matter is fashioned into this soft skinned, pewny bodied animal. This animal with an extraordinary brain. Because of the DNA blueprint that we’ve evolved, our bodies can take the recycled matter of the universe (hydrogen, iron, carbon, calcium… ) and build a huge and complex brain inside this skull. And, suddenly, this animal is conscious.

Until now, it’s as if the universe’s matter has been in a darkened room… but now the shutters have been pushed open and this consciousness gives us a glimpse of a sun-lit landscape.

We have a sense of ourselves in time and space. We can see ourselves relative to yesterday and tomorrow, relative to others like us, and other species. We can look back into the deep geological past, and fashion a sense of the future.

This is an extraordinary moment in the history of species on this planet – that one species should emerge that could be so bright, and adapt the world around it so well, that we could become a geophysical force on the planet, that we could bring about changes in the physical world that previously could only be done by continental drift, volcanic eruptions or meteor strikes (quoting Edward Wilson).

But this unusual consciousness, this window on the world, won’t last long. If we’re lucky, each of us will get 75 or 80 years… maybe 90…

Then the shutters will pull closed. This heart will stop. The bioelectrical pulses in this brain will dim and cool, taking with them the memories and ideas and sense of self which constitute Me.

This body will leach back into the nutrient cycle where it will continue turning over between water, plant, animal, manure, soil, air.

The human species, too, will dwindle into extinction. All species do, eventually. And other species will rise up out of that nutrient cycle, and fall back into it as the universe continues to recycle matter… one species’ dying remains becoming the nutrients from which the next species can be born, one species handing on its genetic blue print for another to adapt and mould as it fits into a new environmental niche.

Then, in about 5 billion years time, our sun will swell and… BOOM, it’ll explode, incinerating its planets and blasting all this matter out across space, returning it to the dust from which it once came.

That’s us, matter sprinkled out across space. To adapt the Edward Abbey quote, that “is immortality enough for me”.

The problem with death, in this context, is that it’s a bit like having the book slammed shut on you before you’ve read the final chapters.

Eighty years, that’s all the time we have to read the pages of this book, to cram our heads with enough stuff so that we can try and appreciate the extraordinary gift that this consciousness is, the extraordinary vessel that is this body, the extraordinary planet that is our incubator and the billions of years of evolutionary craftsmanship that handed our species the blueprint that allows us consciousness.

And that’s what the study of history is all about – learning to appreciate the pages of this book, as they unfold around us, even while we’re reading a Marxist explanation for the migrant labour system.

“Our Sun is a second- or third-generation star. All of the rocky and metallic materials we stand on, the iron in our blood, the calcium in our teeth, the carbon in our genes were produced billions of years ago in the interiors of a red giant star. We are made of star-stuff.” (Carl Sagan, Cosmos)

“If my decomposing carcass helps nourish the roots of a juniper tree or the wings of a vulture – that is immortality enough for me.” Edward Abbey, naturalist and author (1927-1989)

Scorched

Rational Writing by Leonie Joubert