A Larger Perspective: Life on Earth
Geologic evidence suggests that gravity first spun Earth together from star remnants and space dust about 4.5 billion years ago. Gradually it grew, collecting more and more matter through cosmic collisions, eventually partitioning into several layers as lava spewed through cracks onto its cooling surface. At one point, we even collided with another small planet, spitting out our very own moon. When we gained enough mass to have our own protective gravity field, our volatile early years settled down and basins began to form, later filling with water and differentiating our continents. Our molten inners learned how to emerge in a more distinct fashion through several established channels across the globe, and they have been pushing our continents around the world ever since[i].
Meanwhile, the sun soaks up water from our oceans and cycles it through the atmosphere. Pressure differences generate wind and move our air around the world, taking these water molecules along for the turbulent ride during their brief atmospheric spells. Eventually these molecules cool and drop back down to Earth, carving their way through the surface and shaping our landscapes as they head back to sea. All the while other important elements ride their own biological, chemical and physical cycles through Earth’s atmosphere and crust. And so we cycle around the sun, who cycles around our galaxy, the Milky Way, who itself is zooming through the universe.
Our planet has lived a chaotic life, growing up through sublime, unrepeatable cosmic and biological events. It’s atmospheric, oceanic and geologic systems are vast, continuous, and in constant flux, natural hazards like tornadoes, blizzards, and earthquakes unavoidable results of the incessant flows of energy that make life possible. As astrobiologist David Grinspoon describes, “we live on the convoluted, shifting shoreline between cycles of earth and sky… incessantly driven by the sun above and the heat below”[ii] — certainly not an inert, aged rock.
“The only difference between nonliving and living systems is in the scale of their intricacy.”[iii]
James Lovelock, The Gaia Hypothesis, 1979
As astrobiologists Grinspoon and James Lovelock describe, life is “bound to… the fluid media of oceans, atmosphere,”[viii] “enabled and sustained by the great cyclic flows of carbon, nitrogen, oxygen, sulfur and phosphorous.”[ix] It is first and foremost inherently dynamic, responding to Earth’s flux by discovering new alliances and more successful genetic variations. From anaerobic microbes to oxygen
dependent, complex organisms; from dinosaurs,
to wooly mammoths, to human beings; from
recycling the cells in our bodies[x], to our
cognitive development as social creatures,
the biosphere’s journey has been one of
constant adaptation.
We see this cooperative nature in alliances throughout the biosphere –
in honeybees and flowering plants, in lichen, in clownfish and sea anemones. Our very own bodies’ biomass and metabolism are largely dominated by complex microbial ecologies processing the nutrients we receive from other plants and animals[xiii]. Even mitochondria — the organelles in our cells that power cellular activity — are thought to once have been freely living bacteria, who at one point discovered such a mutually beneficial relationship with our ancestral cells that the two eventually became one[xiv].
We can find more collaboration in life’s resourcefulness. As Lovelock said, the biosphere has a knack for “adapting to change and converting a murderous intruder into a power friend”[xv]. Fungi transform toxins into food. A whole taxonomy of decomposers exists, who get their food from dead or decaying organisms. The very air we breathe and depend on was once poisonous to life. “Part of the resilience of nature,” as activist Adrienne Marie Brown describes, “is that nothing… is wasted… Everything is food, fuel, compost, a home for some other creature… the cycle of life ultimately makes use of everything.”[vxi]
This journey is made possible by genetic intricacy, as many ways of being offer many solutions to changing environmental
conditions, and more security in the face of destruction. Billions of
different microorganisms keep our biosphere afloat by cycling key
nutrients through our oceans, soils and atmosphere. Species partake in complex food webs, cross pollinating skills and assets through various alliances and interdependencies. Meanwhile, organisms perpetually mate and reproduce, mutating and interchanging their gene pools, diverging into new species. As Grinspoon describes, “the history of life shows a complex, variable, and always changing pattern of diversity.”[xi]
And alas, life has capitalized on its diversity through its interconnectivity – through the organic molecules, habitats and relations shared amongst living beings. From early microbial life merging into multicellular, multi-organ organisms, to the many symbiotic relationships holding up our ecosystems, “many of life’s most important evolutionary innovations resulted from assimilation, the fusion of formally separate individuals, the formation of cooperatives, and the
sharing of genes and traits.”[xii]
Ecological research thus shows us that the history of evolution is not story of competition, but one of collaboration and deep interdependence. Life’s success on this chaotic planet has depended not on its individual parts, but on the connections between them. As Grinspoon describes, “survival of the fittest still applies, but often the fittest are those assemblages of organisms that creatively merge into new kinds of individuals.”[xvii] And we humans are deeply engrained in this interconnected network, from the microbes in our gut, to the organisms we eat, to the air we breathe. We need biological diversity and intimacy with our environment — and each other — in order to survive.
Around 3.8 billion years ago, the oceans of this shoreline gave birth to a curious assembly of matter — one that was newly complex and self-reproducing. Organic molecules had produced the cell, the building block for life. These microbiota began experimenting with different arrangements, and eventually merged into multicellular organisms[iv]. Later on, around 542 million years ago, on the tail end of an ice age and when Earth’s oxygen levels were just right, life suddenly became complex. Plant and animal forms propagated around the globe in a dramatic increase in biodiversity, quickly (geologically speaking) finding their way onto land. All across the world, life continued to mutate, fuse and trade genes to find better answers to survival, eventually taking over the planet[v].
Along the way, asteroids have crashed into Earth, volcanic activity has blighted our atmosphere and our oceans, jumps in atmospheric gasses like methane have catastrophically transformed our global climate[vi]. Life was almost wiped out entirely when Earth’s atmosphere was first flooded with oxygen (a gas which, up until then, was poisonous to cells) around 2.5 billion years ago, when pesky little cyanobacteria discovered how to turn sunlight into food[vii]. But with its array of genetic options and collaborative nature, life discovered new ways to survive, and sailed on. Crisis after crisis, life managed to bounce back stronger than before, doing so by becoming more flexible, more complex, and more connected. It is these core pillars — adaptability, complexity and interconnectedness — that have given life its resilience. A quick
glance at the biosphere tells us this quite clearly.
[i] From “The Evolution of Earth.” by C. Allgre and S. Shneider, 2005 July 1. Scientific American. https://www.scientificamerican.com/article/evolution-of-earth/.
[ii] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 90. Grand Central Publishing.
[iii] From “The Gaia Hypothesis: A New Look at Life on Earth” by J. Lovelock, 1979, p. 62. Oxford University Press.
[iv] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 104. Grand Central Publishing.
[v] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 228. Grand Central Publishing.
[vi] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 103. Grand Central Publishing.
[vii] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 106. Grand Central Publishing.
[viii] From “The Gaia Hypothesis: A New Look at Life on Earth” by J. Lovelock, 1979, p. 5. Oxford University Press.
[ix] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 56. Grand Central Publishing
[x] See “Molecular Cell Biology” by H. Lodish, A. Berk, S. Zipursky, P. Matsudaira, D. Baltimore and J. Darnell, 2000, 4th edition, Section 1.4: The Life Cycle of Cells. W. H. Freeman.
[xi] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 87. Grand Central Publishing.
[xii] From “Earth in Human Hands: Shaping Our Planet’s Future” by D. Grinspoon, 2016, p. 65. Grand Central Publishing.
[xiii] See “Introduction to the human gut microbiota” by E. Thursby and N. Juge, 2017, The Biochemical Journal 474(11), p. 1823 – 1836. https://doi.org/10.1042/BCJ20160510.
[xiv] From “Earth in Human Hands: Shaping Our Planet’s Future” by David Grinspoon, 2016, p. 64. Grand Central Publishing.
[xv] From “The Gaia Hypothesis: A New Look at Life on Earth” by James Lovelock, 1979, p. 31. Oxford University Press.
[xvi] From “Emergent Strategy: Shaping Change, Changing Worlds” by A. Brown, 2017, p. 131. AK Press.
[xvii] From “Earth in Human Hands: Shaping Our Planet’s Future” by David Grinspoon, 2016, p. 65. Grand Central Publishing.