Scientists are re-examining the role of symbiosis in the evolution of life, and their findings are helping to shed light on one of the greatest and oldest questions in science: how did life begin?
Wherever you are reading this, look around you. Every living thing you can see - other people, pets, birds flying past, trees, flowers, mushrooms, fish - is here because of unions between different species.
Classic cases are lichens (typically formed of algae and fungi) or corals (made of algae and animal components), but these examples underplay just how far and deep symbiosis goes. I make the case that symbiosis - which means living together - has been neglected in our explanation of biology and ecology.
It's not just that I think it's a shame that its significance has been unappreciated; it's that, and all plants rely on symbiosis to grow and to produce all the food we eat. But this isn't widely recognised. Since before Charles Darwin published his theory of evolution, and even more so afterwards, we have emphasised the role of competition in the evolution of life, fuelled by the idea of nature being red in tooth and claw.
What I didn't expect to find when researching my book is that the growing understanding of this togetherness, and the way it forces us to look at the world anew, is helping to demystify one of the greatest and oldest questions in science: how did life begin? The picture that is coming into view is set to reshape our definition of what life is - and inform the search for alien life.
The mission to decode how the earliest cells evolved has a long history. Darwin was reluctant to speculate publicly on life's origins, but: If (& oh what a big if) we could conceive in some warm little pond with all sorts of ammonia & phosphoric salts, light, heat, electricity present, that a protein compound was chemically formed, ready to undergo still more complex changes. Instead, much of the current excitement focuses on deep-sea hydrothermal vents.
The tiny pores in the rocks act like ready-made cells, and in the tension between the hot alkaline water emitted from the vents and the colder, acidic seawater, you have an electrochemical gradient that could power biochemical reactions. Which is another way of saying that it could power life. The internal pores of the vents have cell-like structures with electrically charged catalytic surfaces, while the continuous flow gives continuous reactivity, says biochemist.
I love about this idea is that it takes the insight of some of the great scientists of the past and turns it into a testable hypothesis. In 1866, Then, in 1985, physicist Freeman Dyson took Schrödinger's idea and fused it with the breakthrough work of the microbiologist Lynn Margulis. Margulis had marshalled evidence to definitively show that the complex cells of plants, animals and fungi originated in an ancient act of.
Inspired by this, Dyson suggested that life had two origins. First came early versions of cells called protocells, in which metabolic processes - the biochemical reactions that provide energy - got going. Later, he thought, came the development of a way to store genetic information that could act as a replicator: a strand of RNA. These two proto-life forms, he said, merged through a process akin to symbiosis.
Now, these ideas are being put to the test. To see how this is being done, I visited Lane's lab to observe how he and his colleagues are mimicking the possible conditions at the origin of life and starting to make their own protocells. We're looking for an environment, says Lane, where geochemistry gives rise seamlessly to biochemistry - where non-life shades into life.
She is working to reproduce one of the first stages in metabolism: the reaction of carbon dioxide and hydrogen to make simple organic compounds, such as formate and acetate. She shows me the Y-shaped piece of apparatus she uses to simulate a hydrothermal vent. Down one side of the Y we put ocean fluid, down the other is vent fluid, she tells me. By doing this, we try to mimic the ancient hydrothermal environment.
It all takes place in a controlled-atmosphere chamber without oxygen present, a bubble of the ancient Earth from 4 billion years ago. A chip detects any organic molecules produced by the flow. The propensity of molecules to self-assemble has, for me, been one of the most startling recent discoveries in this field - in particular, the fact that metabolic processes themselves arise spontaneously. They got going prior to the origin of life.
Biochemists talk of molecules moving towards a thermodynamic minimum. That's their way of saying the resting state of molecules. It means molecules, even complex ones, can form simply because that's what chemicals and molecules want to do; like putting a ball at the top of a hill and it rolling to the bottom because that's the natural place it wants to be, molecules want to travel along preferred biochemical and thermodynamical pathways
Symbiosis Evolution Origin Of Life Deep-Sea Hydrothermal Vents Biochemistry
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