A LIVING SEA
‘We consider naïve the early Darwinian view of “Nature red in tooth and claw”.
Now we see ourselves as the products of cellular co-operation –
cells built up from other cells.
Partnerships between cells once foreign, and even enemies to each other,
are at the very root of our being.’
Lynn Margulis & Dorion Sagan
‘We consider naïve the early Darwinian view of “Nature red in tooth and claw”.
Now we see ourselves as the products of cellular co-operation –
cells built up from other cells.
Partnerships between cells once foreign, and even enemies to each other,
are at the very root of our being.’
Lynn Margulis & Dorion Sagan
Around 4 billion years ago in a relatively stabilized solar environment the first life on Earth emerged. We don’t know where exactly or how, but most scientists place it somewhere in Earth’s warm, murky waters.
As with the first bits of matter, it happened on a scale too small to be visible except with the most powerful microscopes, often called a nano-scale, and again it would change everything. Perhaps it started deep in the ocean, alongside volcanic vents that scientists call black smokers, or perhaps in the shallow waters around the continents. And it might have been prompted by an energy surge, a lightning strike or an asteroid impact.
It started with carbon compounds like the amino acids also found in space, but a few of these acids evolved into a new kind of molecule: the first enzymes, proteins and viruses. Then RNA emerged, and eventually DNA - essential as the source of genes, the basic units of heredity. These DNA molecules clumped together, enclosing themselves in a protective membrane to form Earth’s first tiny organisms, containing one simple cell. The technical term for them is prokaryotes, but their direct descendants are usually called microbes or bacteria, visible to us only under a microscope.
With life came consumption, reproduction and competition. Deep ocean organisms might have gained energy by scavenging gases from volcanic ocean plumes, as some of today’s prokaryotes still do. And wherever they were they split into two identical beings (clones) at such a rate that within a day each one had produced a billion copies of itself. It was millions of years before the population exploded enough to cause Earth’s first food crisis. But then nearly all of them perished.
The reason why they didn’t all die was that some started to make their own food.
Using the energy of the Sun’s rays, which penetrated up to 200 metres below the water’s surface, they somehow split water’s tightly-knit molecules and carbon dioxide molecules to create carbohydrates, releasing the leftover oxygen into the surrounding water.
Photosynthesis had emerged. Scientists call the beings that were the first to use it blue-green bacteria, coloured by the photo-synthesising pigment chlorophyl. They paved the way for algae and later land-plants.
Most scientists explain the evolution of these blue-green bacteria as being due to random mutations in their genes caused by repeated self-copying or by changed environmental conditions. They say that most mutations have a negative or minimal effect but a few are useful, and then as the cell multiplies it somehow trades them to neighbouring cells. This is how certain single-cell organisms began to specialize in photosynthesis, and then how it became an established pattern.
But there are scientists, like Lynn Margulis quoted above, who see useful mutations as a product of epigenetic control, in other words operating above the level of the gene. In this analysis even single-celled life brought with it the need for creative attentiveness to one’s surroundings, so that the cell might survive by adapting in response to danger or stress. The technical term for this is autopoiesis, literally ‘self-creation’, and it is seen as a manifestation on the self-organising system of our Universe as a whole.
These scientists are members of a group of writers, dating at least from Henri Bergson 100 years ago, who argue that creativity is a prime factor in evolution, with effective experiments fed back into the organism, reinforced, and incorporated from then on. In other words among Earth’s earliest and simplest organisms a few survived by creating photosynthesis, and then passed it on to others.
If this theory sounds strange, think about the rapid sharing of useful mutations among today’s bacteria, and even viruses. They are Earth’s most successful survivors, so at least it seems worth considering. Of course it is not the whole picture – as we shall see.
Back in our story, the freed oxygen atoms first combined with iron atoms dissolved in the water in our planet’s first example of rusting. This created insoluble molecules of iron oxide, which settled on the ocean floor. This is the origin of the iron-ore deposits in the Hammersley Basin in today’s Western Australia - on dry land because of subsequent tectonic plate movement. They are said to be the greatest on Earth.
But as the blue-greens kept multiplying, oxygen built up in the water and then in the atmosphere, which, as in our solar system’s other planets, until then had no free oxygen atoms.
The positive effects for life on Earth included global cooling, and also a layer of ozone (a special form of oxygen) forming about 25 kilometres up, which began to absorb most of the Sun’s ultraviolet rays. These would both allow later organisms to live out of the water and increase in diversity.
The negative effects were that free-floating oxygen was highly flammable and also poisonous to the existing organisms. Again nearly all of them died, although a small number were in niches sheltered from the oxygen, for instance around black smokers, and others somehow found new niches, such as stagnant marshes.
But now some photosynthesizing microbes managed to adapt in a radical new way. In the inter-tidal zone of several shorelines a few combined forces to form colonies. At low tide the multiplying cells exposed at the top died, but their bodies left a filtering layer that protected the rest until the water returned. Today we call these colonies stromatolites.
(Shark Bay in Western Australia has the remains of ancient ones, now rock, as well as many that are still forming. Together they show the cycle of non-living matter evolving into living creatures and then slowly returning to a non-living form.)
Over time a few other microbes adapted by actually taking up the oxygen in the water and releasing carbon dioxide. They were the pioneers of breathing, and by passing this on to more microbes they paved the way for animals. And other microbes were breaking up nitrates in the water, releasing nitrogen in a form that still other microbes could take up.
So in order to survive, organisms gained energy by consumption, multiplied by reproduction, competed for food, adapted by various kinds of specialization and multiplied again. By sheer weight of numbers some had completely changed their environment, while others were showing their resilience by living much as before, in a safe niche within the new environment.
And now the activities of various organisms were offsetting each other, modifying the ratio of different gases in the atmosphere. From this point on, in a precarious compensatory process discovered by James Lovelock, diverse organisms would help in the recycling of a range of elements needed for life. The most imperative are hydrogen, carbon, nitrogen and oxygen, but there are many others as well, including our minerals, most of which are needed by different life-forms in minute quantities.
The process is precarious because when too much of a particular element builds up to a crucial tipping point, Earth restores the balance very suddenly, and this means that many individuals have to be sacrificed. This phenomenon of self-regulation, in which the biosphere (a special sixth ‘layer of life’) plays an essential role, has given rise to Lovelock’s name for our planet to remind us that it is unique in our solar system, and as far as we know way beyond: Gaia.
Venus may have microbes in its soupy sulphuric acid atmosphere; Mars may have had them until its liquid water froze. And Jupiter and Saturn both have moons with ice-coated water: Europa and Titan respectively. Any organisms arising there would use thermal energy from their planet’s core rather than from the Sun, as Earth’s early microbes probably did. But the Sun is still too faint at that distance to allow the photosynthesis that is needed for the evolution of more complex life.
Our scientists are discovering that the Milky Way has quite a few dispersed stars with orbiting planets of various sizes. But they are many light-years away, and we are a long way from having the technology to detect if there is any kind of life on them. Of course we have made a few eager attempts to let any sentient beings out there know that we are here.
Back in our story, some microbes had apparently been invading or engulfing others when times were hard in order to gain energy from them. But by around 2.5 billion years ago this was leading in some cases to separate microbes losing their individuality but gaining security by becoming integral parts of a complex single-celled organism that scientists call a eukaryote. (The remains of some have been found in the Bungle Bungles, in Western Australia’s Kimberley region.)
These new, still tiny organisms were very efficient because they had a coordinating nucleus with specialist organelles around it. Each performed a different task for the whole: such as moving, photosynthesizing, absorbing food, taking in oxygen, or fighting off invaders. Thus emerged the transformation of competition into synergy, which is the energy created when distinct parts of a system work collectively.
Like their simple ancestors eukaryotes traded genes, but now they were in tightly coiled threads that we know as chromosomes, most of them within the cell’s nucleus. With these chromosomes they paved the way for sexual reproduction. Their direct descendants today are amoeba, but they are also the stuff of all beings other than simple bacteria.
Meanwhile Earth's tectonic plates kept on thickening, moving, splitting and colliding, bringing lots of lava and rock up from the mantle, and transforming areas of ocean-floor into land and vice versa. This is how ancient and abundant deposits of minerals that have proved so valuable for humans became available for mining. (It was in this period that gold was laid down at today’s Kalgoorlie, as well as lead, zinc and silver at today’s Broken Hill.)
But remember, many of the crust’s disturbances take place deep under water, as happened in the Indian Ocean earthquake and tsunami at the end of 2004.
Just think, the plates’ average movement of four centimetres a year means that every million years each one moves about 40 kilometres this way and that – that’s about 200,000 kilometres over the last 4 billion years.
As with the first bits of matter, it happened on a scale too small to be visible except with the most powerful microscopes, often called a nano-scale, and again it would change everything. Perhaps it started deep in the ocean, alongside volcanic vents that scientists call black smokers, or perhaps in the shallow waters around the continents. And it might have been prompted by an energy surge, a lightning strike or an asteroid impact.
It started with carbon compounds like the amino acids also found in space, but a few of these acids evolved into a new kind of molecule: the first enzymes, proteins and viruses. Then RNA emerged, and eventually DNA - essential as the source of genes, the basic units of heredity. These DNA molecules clumped together, enclosing themselves in a protective membrane to form Earth’s first tiny organisms, containing one simple cell. The technical term for them is prokaryotes, but their direct descendants are usually called microbes or bacteria, visible to us only under a microscope.
With life came consumption, reproduction and competition. Deep ocean organisms might have gained energy by scavenging gases from volcanic ocean plumes, as some of today’s prokaryotes still do. And wherever they were they split into two identical beings (clones) at such a rate that within a day each one had produced a billion copies of itself. It was millions of years before the population exploded enough to cause Earth’s first food crisis. But then nearly all of them perished.
The reason why they didn’t all die was that some started to make their own food.
Using the energy of the Sun’s rays, which penetrated up to 200 metres below the water’s surface, they somehow split water’s tightly-knit molecules and carbon dioxide molecules to create carbohydrates, releasing the leftover oxygen into the surrounding water.
Photosynthesis had emerged. Scientists call the beings that were the first to use it blue-green bacteria, coloured by the photo-synthesising pigment chlorophyl. They paved the way for algae and later land-plants.
Most scientists explain the evolution of these blue-green bacteria as being due to random mutations in their genes caused by repeated self-copying or by changed environmental conditions. They say that most mutations have a negative or minimal effect but a few are useful, and then as the cell multiplies it somehow trades them to neighbouring cells. This is how certain single-cell organisms began to specialize in photosynthesis, and then how it became an established pattern.
But there are scientists, like Lynn Margulis quoted above, who see useful mutations as a product of epigenetic control, in other words operating above the level of the gene. In this analysis even single-celled life brought with it the need for creative attentiveness to one’s surroundings, so that the cell might survive by adapting in response to danger or stress. The technical term for this is autopoiesis, literally ‘self-creation’, and it is seen as a manifestation on the self-organising system of our Universe as a whole.
These scientists are members of a group of writers, dating at least from Henri Bergson 100 years ago, who argue that creativity is a prime factor in evolution, with effective experiments fed back into the organism, reinforced, and incorporated from then on. In other words among Earth’s earliest and simplest organisms a few survived by creating photosynthesis, and then passed it on to others.
If this theory sounds strange, think about the rapid sharing of useful mutations among today’s bacteria, and even viruses. They are Earth’s most successful survivors, so at least it seems worth considering. Of course it is not the whole picture – as we shall see.
Back in our story, the freed oxygen atoms first combined with iron atoms dissolved in the water in our planet’s first example of rusting. This created insoluble molecules of iron oxide, which settled on the ocean floor. This is the origin of the iron-ore deposits in the Hammersley Basin in today’s Western Australia - on dry land because of subsequent tectonic plate movement. They are said to be the greatest on Earth.
But as the blue-greens kept multiplying, oxygen built up in the water and then in the atmosphere, which, as in our solar system’s other planets, until then had no free oxygen atoms.
The positive effects for life on Earth included global cooling, and also a layer of ozone (a special form of oxygen) forming about 25 kilometres up, which began to absorb most of the Sun’s ultraviolet rays. These would both allow later organisms to live out of the water and increase in diversity.
The negative effects were that free-floating oxygen was highly flammable and also poisonous to the existing organisms. Again nearly all of them died, although a small number were in niches sheltered from the oxygen, for instance around black smokers, and others somehow found new niches, such as stagnant marshes.
But now some photosynthesizing microbes managed to adapt in a radical new way. In the inter-tidal zone of several shorelines a few combined forces to form colonies. At low tide the multiplying cells exposed at the top died, but their bodies left a filtering layer that protected the rest until the water returned. Today we call these colonies stromatolites.
(Shark Bay in Western Australia has the remains of ancient ones, now rock, as well as many that are still forming. Together they show the cycle of non-living matter evolving into living creatures and then slowly returning to a non-living form.)
Over time a few other microbes adapted by actually taking up the oxygen in the water and releasing carbon dioxide. They were the pioneers of breathing, and by passing this on to more microbes they paved the way for animals. And other microbes were breaking up nitrates in the water, releasing nitrogen in a form that still other microbes could take up.
So in order to survive, organisms gained energy by consumption, multiplied by reproduction, competed for food, adapted by various kinds of specialization and multiplied again. By sheer weight of numbers some had completely changed their environment, while others were showing their resilience by living much as before, in a safe niche within the new environment.
And now the activities of various organisms were offsetting each other, modifying the ratio of different gases in the atmosphere. From this point on, in a precarious compensatory process discovered by James Lovelock, diverse organisms would help in the recycling of a range of elements needed for life. The most imperative are hydrogen, carbon, nitrogen and oxygen, but there are many others as well, including our minerals, most of which are needed by different life-forms in minute quantities.
The process is precarious because when too much of a particular element builds up to a crucial tipping point, Earth restores the balance very suddenly, and this means that many individuals have to be sacrificed. This phenomenon of self-regulation, in which the biosphere (a special sixth ‘layer of life’) plays an essential role, has given rise to Lovelock’s name for our planet to remind us that it is unique in our solar system, and as far as we know way beyond: Gaia.
Venus may have microbes in its soupy sulphuric acid atmosphere; Mars may have had them until its liquid water froze. And Jupiter and Saturn both have moons with ice-coated water: Europa and Titan respectively. Any organisms arising there would use thermal energy from their planet’s core rather than from the Sun, as Earth’s early microbes probably did. But the Sun is still too faint at that distance to allow the photosynthesis that is needed for the evolution of more complex life.
Our scientists are discovering that the Milky Way has quite a few dispersed stars with orbiting planets of various sizes. But they are many light-years away, and we are a long way from having the technology to detect if there is any kind of life on them. Of course we have made a few eager attempts to let any sentient beings out there know that we are here.
Back in our story, some microbes had apparently been invading or engulfing others when times were hard in order to gain energy from them. But by around 2.5 billion years ago this was leading in some cases to separate microbes losing their individuality but gaining security by becoming integral parts of a complex single-celled organism that scientists call a eukaryote. (The remains of some have been found in the Bungle Bungles, in Western Australia’s Kimberley region.)
These new, still tiny organisms were very efficient because they had a coordinating nucleus with specialist organelles around it. Each performed a different task for the whole: such as moving, photosynthesizing, absorbing food, taking in oxygen, or fighting off invaders. Thus emerged the transformation of competition into synergy, which is the energy created when distinct parts of a system work collectively.
Like their simple ancestors eukaryotes traded genes, but now they were in tightly coiled threads that we know as chromosomes, most of them within the cell’s nucleus. With these chromosomes they paved the way for sexual reproduction. Their direct descendants today are amoeba, but they are also the stuff of all beings other than simple bacteria.
Meanwhile Earth's tectonic plates kept on thickening, moving, splitting and colliding, bringing lots of lava and rock up from the mantle, and transforming areas of ocean-floor into land and vice versa. This is how ancient and abundant deposits of minerals that have proved so valuable for humans became available for mining. (It was in this period that gold was laid down at today’s Kalgoorlie, as well as lead, zinc and silver at today’s Broken Hill.)
But remember, many of the crust’s disturbances take place deep under water, as happened in the Indian Ocean earthquake and tsunami at the end of 2004.
Just think, the plates’ average movement of four centimetres a year means that every million years each one moves about 40 kilometres this way and that – that’s about 200,000 kilometres over the last 4 billion years.
* * * * * * *
(boojum.as.arizona.edu)Venus is so hot
that tin and lead would melt on its surface.
Mars is so cold
that even carbon dioxide (dry ice) freezes on the winter pole.
Earth is at the right temperature
for most of its water to remain as a liquid,
and this water provides the basis for life.
(Another image available through Google images)
I intend to post the five scenes of Our First Age throughout June,
and then one Age each month until December.
That means that the Epilogue and Two-Page Timeline will be posted in January.
If you would rather have a free email copy of the book, please sign in to my Guestbook
(see first post: An Introduction),
making sure that you ask for your entry to be kept private.
that tin and lead would melt on its surface.
Mars is so cold
that even carbon dioxide (dry ice) freezes on the winter pole.
Earth is at the right temperature
for most of its water to remain as a liquid,
and this water provides the basis for life.
(Another image available through Google images)
I intend to post the five scenes of Our First Age throughout June,
and then one Age each month until December.
That means that the Epilogue and Two-Page Timeline will be posted in January.
If you would rather have a free email copy of the book, please sign in to my Guestbook
(see first post: An Introduction),
making sure that you ask for your entry to be kept private.
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