The Purpose of Life

EarthTimelineIn The Life and Death of Planet Earth, authors Peter Ward and David Brownlee trace the entire history of our planet, from its formation 4.5 billion years ago (8 billion years after the Big Bang) to its inevitable demise 7.5 billion years from now, when our sun expands just before its death and its heat incinerates our entire galaxy. They argue that while short-term weather is highly unpredictable, longer-term phenomena are less complex and hence very predictable. We are, they assure us, half way through the brief one-billion-year period during which our planet can support any plant or animal life, after which it will revert to a hellishly hot planet capable of supporting only the bacteria from which all complex life evolved.

The charts at right show, from top to bottom, (a) major events in the full 12 billion year life of Earth, (b) magnified 10 times, the 1 billion year period that supports complex life forms and its five known major extinction events (the last of which extinguished the dinosaurs), and (c) magnified 1000 times, our species’ brief stint on the planet. The red line shows the average Earth surface temperature, to the best of our knowledge, and the pale green band is the temperate range that can support plant and animal life. All of the blips to the left represent ice ages. The ones that go all the way to -70C are ‘snowball Earth’ periods when the planet was completely covered in ice miles thick. The smaller ones are partial glaciations, which mysteriously ceased about 250 million years ago and then started up again about 2.5 million years ago and are expected to continue, every 100,000 years or so, for another 2 to 10 million years, after which the planet will again inexorably heat up to unbearable levels. We are on the cusp of another ice age, perhaps in 5,000 years, and the only thing scientists can’t agree upon is whether our human-made destruction of the ozone layer will delay it a few thousand years, or accelerate it. They can agree that global warming will bring cataclysmic change, violent and unstable weather, and huge changes to our planet’s topography.

Ward and Brownlee claim not to believe fully in Gaia theory, because the behaviour of our planet does not fully meet the scientific conditions necessary to qualify it as an ‘organism’ (e.g. it does not reproduce). But as I read the book I began to understand why all life on Earth does act, usually, in harmony and cooperation in collective interest, just as the organs of our bodies do. The task of regulating Earth’s temperature is such a massive and constantly-challenging job that it takes all of us, working together, to succeed at it. In Darwinian terms, individual life-forms competing strictly in their own self-interest will continually fail to survive the sharp temperature changes their selfishness allows. Only a life model with global awareness, respect and cooperation can sustain any of us in this temperature-fragile environment. Plant and animal life evolved a half billion years ago as a ‘conscious’ mechanism to perpetuate itself by regulating the temperature of its host planet. And it has done that awesome task remarkably well: Despite extinction events like meteor impacts, massive volcanic eruptions and ice ages, complex life has endured on our planet and re-regulated the planet’s temperature remarkably quickly for half a billion years, and may be able to do so for another half a billion if some arrogant and selfish species like humanity doesn’t mess it up.

In the blink of an eye since humans emerged on the planet, and more specifically in the even briefer period since we built civilization, we have extinguished more species of life on the planet and transformed the life-sustaining biosphere more severely and quickly than any of the previously recorded extinction events. Civilization detached humanity from the global consciousness that regulated Earth’s temperature, and allowed us to pursue a selfish, reckless, and environmentally destructive course. Our biosphere — the respiration of all plants and animals on the planet, the movement of the ocean currents and atmosphere, regulates Earth’s surface temperature astonishingly well, and adapts to or quickly recuperates from external events and anomalies (like movement of the continental plates, meteor impacts, large-scale volcanic activity, changes in our orbit around the sun, the tilt and wobble of the planet’s axis, and our planet’s periodic passage through vast amounts of cosmic debris and dust). But our burning of fossil fuels, pollution of the air and water, and diminishing of the planet’s forest cover and desertification of much of the planet’s surface are throwing a monkey-wrench into this finely-tuned mechanism of regulation.

Even if we are somehow able to regain our global consciousness and work with the rest of Gaia to regulate Earth’s temperature in all our interests, we are still only a half billion years from the time when this self-regulation mechanism will be inadequate to cope with the sun’s ever-growing heat and the continuous depletion of carbon dioxide. By that time all plant and animal life on the planet will die off, and our blue, green and occasionally white planet will turn permanently brown and red, a twin of Mars. And then the heat will evaporate the oceans bringing the end of even microbial life, so that by the time our galaxy collides in 3.2 billion years with Andromeda the planet will be virtually lifeless.

So we are very much like an organ in the human body acting up so irresponsibly that we are putting the whole body at risk. The analogy is startling, as the authors point out:

You are made of more cells than there are stars in the Milky Way galaxy, and each cell is a miniature city with its own highways, factories, waste-processing plants, and a coil of DNA recording the genetic instructions necessary to make a copy of you. The cells in turn have combined to make a complex organism that can move, eat, breathe, reproduce, repair itself, think and dream. Yet as astonishing as our biology is, we are also mortal, forever in peril of disease, puncture, and the inevitable dissolution caused by wear and tear of time. Our home planet is similarly complex and similarly marvelous.

How arrogant, how foolish we are, to believe that the world revolves around us, that it is here for our benefit! What will it take for us to rediscover the wisdom that all other life instinctively knows, that our purpose is to do our small part to help regulate the temperature and well-being of the whole organism of which we are inextricably a part, this astonishingly rare and vibrant and wondrous blue-green ball, for the benefit of all life, for the brief period we have the privilege to be alive as a part of its awesome and finite history?

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6 Responses to The Purpose of Life

  1. Avi Solomon says:

    Amazing Post Dave!Along with serving Great Nature, what other deeper purpose may there be for man?This nursery rhyme hides a clue: “Baa, baa, black sheep,Have you any wool?Yes sir, yes sir,Three bags full.One for the master,One for the dame,And one for the little boyWho lives down the lane.”

  2. Conor says:

    Arrogance, no doubt – But hommonids biggest problem right now is myopia and inercia (did I spell that right). Ultimately, I really think we are getting better, it’s just realizing this before be bare the fruits of our own destruction and then leave no evidence for anyone to care about in the first place.Little Boy Down The Lane.

  3. Herbinator says:

    How about this for your pipe … consider two options:1) Destroying mankind will save the planet; 1a) The planet will destroy mankind; or2) Mankind evolved to save the planet; 2a) To release locked-away hydrocarbons to create warming.There is an assumption of intellect. A smart planet might do 2 then 1.

  4. Life Tenant says:

    If Earth is an organism that acts intentionally to manage her physiology in the manner you describe, then consider the fact that the evolution of oxygen-generating organisms in an anaerobic biosphere several billion years ago led to a dramatic change in the global ecosystem doubtless accompanied by the extinction of numerous species of bacteria for which oxygen was a poison. This dramatic shift made way for the plants and animals we know and love today. So Gaia is perfectly capable of altering her own balance, sometimes violently, with results both good and bad, depending on your perspective. Now Gaia has engendered humanity. Messy and destructive as we are, our actions will not destroy life on Earth, though we may extinguish ourselves. Have you considered the hypothesis that Mother Earth is bored with the same old same old, and we are the instrument of another violent change to a new balance, a new and interesting array of life on Earth – which we humans may not live to see.

  5. Indigo says:

    And they paved paradise, and put up a parking lot…

  6. Dave Pollard says:

    Wow, what a thoughtful set of responses — thanks everyone. Herbinator: Maybe it’s my bias but I think 1 is quite plausible and 2 is over the top. Life Tenant: Interesting idea, kind of an anthopomorphized version of Gould’s hypothesis of punctured equilibrium in his book Full House. Every once in awhile nature, through massive change, shuffles the deck and redeals, and Gaia needs to contend with a whole new set of cards, and start to organize the players and the game all over again.

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