Biology and Spirituality, part 2

To part 1

It happened, to the best of our ability to tell, just once: an archaeon and a bacterium merged, and both survived as parts of one organism. That happened just once in 4 billion years, and it very easily might not have happened in 8 billion years or 16 billion. (The universe itself, remember, is less than 14 billion years old.)

Life out there may not be all that rare, but eukaryotic life? Maybe in 200 billion galaxies averaging 100 billion stars per galaxy, and 1 to 10 planets per star, only one single spot in the whole wide vast universe happened to produce such a monumentally unlikely thing as eukaryotic life. Maybe.

The science inspires our spirits into the awe and wonder of this amazing fluke – an archaeon absorbing a bacterium and both parts surviving, now as one. With that eukaryotic barrier crossed, then it was off to the races. How did we get to multi-celled organisms? Studies of single-celled eukaryotes called choanoflagellates offers a clue. They reproduce, as all unicellular organisms do,

“by dividing in two, but sometimes the two daughter cells fail to split completely and end up connected by a short bridge. This happens again and again, until there’s a sphere of linked cells, enveloped in a single sheath” (Ed Yong, I Contain Multitudes 56).

This turns out to be helpful because the choanoflagellates are better at catching food as a group than they are on their own. So maybe that’s how the jump to multi-celled organisms got started. And from there came the explosion into 8.7 million species of eukaryotes – some 7 million of them animal species.

Here, then, is a spiritual message – a message of transcending mystery and wonder, and a message that offers us a sense of meaning. What we are, fundamentally – what we humans share with all primates, with all mammals, with all vertebrates, with all invertebrate animals, with all plants, all algae and all fungi – is that we are based on two very different things coming together and, against all odds, making one.

Moreover, life on this Earth has been combining into one in amazing ways every since. Which brings me to the book that our "Science and Spirituality" group is currently reading, which I have quoted from but not named: it’s by Ed Yong, titled, I Contain Multitudes. It’s all about the microbes that live around us, on us, and within us, and how they make our life possible.

I learned, for instance, that human milk has over 200 unique complex sugars called oligosaccharides. That’s far more than any other mammal. Why do we have so many? And here’s the real kicker: babies can’t digest oligosaccharides. They aren’t for the baby – at least not directly. Ed Yong writes that:

“When [milk researcher Bruce] German first learned about Human Milk Oligosaccharides, he was gobsmacked. Why would a mother spend so much energy manufacturing these complicated chemicals if they were indigestible and therefore useless to her child? Why hasn’t natural selection put its foot down on such a wasteful practice? Here’s a clue: these sugars pass through the stomach and small intestine unharmed, and land in the large intestine where most of our bacteria live. So, what if they aren’t food for babies at all? What if they are food for microbes?” (I Contain Multitudes 94)

One particular bacteria species, B. infantis, gobbles up human milk oligosaccharides and, in so doing, releases short-chain fatty acids that feed the infant's gut cells.

“While mothers nourish the microbe, the microbe in turn nourishes the baby” (95).

B. infantis also produces sialic acid which supports the rapid growth of a human infant’s brain.

Throughout the animal kingdom, there is dependence on microbes. As Yong says:

“When we look at beetles and elephants, sea urchins and earthworms, parents and friends, we see individuals, working their way through life as a bunch of cells in a single body, driven by a single brain, and operating with a single genome. This is a pleasant fiction. In fact, we are legion, each and every one of us. Always a ‘we’ and never a ‘me.’” (5)

Microbes,

"help to digest our food, releasing otherwise inaccessible nutrients. They produce vitamins and minerals that are missing from our diet. They break down toxins and hazardous chemicals. They protect us from disease by crowding out more dangerous microbes or killing them directly with antimicrobial chemicals. They produce substances that affect the way we smell. They are such an inevitable presence that we have outsourced surprising aspects of our lives to them. They guide the construction of our bodies, releasing molecules and signals that steer the growth of our organs. They educate our immune system, teaching it to tell friend from foe. They affect the development of the nervous system, and perhaps even influence our behavior.” (12)

There’s a cat microbe called toxoplasma gondii. It only reproduces in the specific environment of a cat’s gut. The cat’s poop teems with this microbes eggs, but the eggs have to get back into some cat’s gut. Rats, which will eat almost anything, eat the cat poop. Now there’s toxoplasma gondii in the rat’s system, and it influences the rat’s behavior – suppressing its normal fear of any place that smells like it might have a cat nearby. So the rat boldly ventures out, is more likely to get eaten by a cat, and thus the toxoplasma gondii happily makes its way back to a cat gut to begin the cycle anew.

In humans, it’s likely that certain microbes in certain numbers, high or low, can shift our mood.

Microbes that are helpful to us in one part of the body can be deadly in other parts. So a large part of the job of containing multitudes is containing all those multitudes. We have elaborate systems with layers of mucus interlaced with bacteriophage viruses to contain the microbes to the area where we need them.

“Microbes subvert our notions of individuality.... Perhaps it is less that I contain multitudes and more than I am multitudes.”

A lot of me inside my skin keeps me going and healthy even though it doesn’t have my DNA. Moreover, what is me doesn’t stop at my skin.

“Every person aerosolizes around 37 million bacteria per hour. This means that our microbiome isn’t confined to our bodies.” (251)

Each of us is walking around in a cloud of...ourselves.

Even so, keep in mind that microbes have their own evolutionary interests, and even the beneficial ones will benefit you only as far as doing so advances their own interests. When Whitman said, “I contain multitudes,” he was addressing the idea that he might be contradicting himself. “Do I contradict myself? Very well then I contradict myself. I am large. I contain multitudes.” But this, too, fits the microbial story – as microbes, push and pull with other microbes and with their hosts the way that contradictory propositions might pull in opposing directions. We are walking bundles of contradictions – our ideas and our organisms pulling in opposite directions at once.

One more lesson from what the study of microbes reveals is that diversity is good. Whether it’s the ecosystem of a forest or the ecosystem of your body, a diverse one is better than an impoverished one. People in hospitals so frequently contract diseases precisely because hospitals have been such sterile places. The best defense against pathogens isn’t the nuclear option of killing all microbes, because then we kill the ones that counteract the pathogens. We’re better off with diversity within us and diversity around us.

Where do we come from? What are we? We are many. E pluribus unum – from many one. It’s not just a political motto, it’s our inescapable biological reality. It’s our inescapable spiritual reality. E pluribus unum. From many, one.

To part 1

Biology and Spirituality, part 1

To part 2

from “Song of Myself”
Walt Whitman

1.
I celebrate myself, and sing myself,
And what I assume you shall assume,
For every atom belonging to me as good belongs to you....
My tongue, every atom of my blood, form’d from this soil, this air....

51.
The past and present wilt—I have fill’d them, emptied them,
And proceed to fill my next fold of the future.
Listener up there! what have you to confide to me?
Look in my face while I snuff the sidle of evening,
(Talk honestly, no one else hears you, and I stay only a minute longer.)
Do I contradict myself?
Very well then I contradict myself,
(I am large, I contain multitudes.)
I concentrate toward them that are nigh, I wait on the door-slab.
Who has done his day’s work? who will soonest be through with his supper?
Who wishes to walk with me?
Will you speak before I am gone? will you prove already too late?

Where do we come from? What are we? Every human culture addresses these questions in some way. Origin myths are part what makes a people a people. What is ours? For Unitarian Universalists today, it’s a story informed by science, which means it is continually revised. Still, we are a faith tradition, not a scientific association.

Where do we come from? What are we? Answers of Unitarian Universalists are many and various and not all consistent. To paraphrase Whitman: Do we contradict ourselves? Very well then we contradict ourselves. We are large. We contain multitudes.

Our faith tradition, informed by science, reaches beyond science in two regards. First: awe, wonder, mystery, transcendence. The first of the sources of the living tradition we share articulated in the Unitarian Universalist Association bylaws is:

“Direct experience of that transcending mystery and wonder, affirmed in all cultures, which moves us to a renewal of the spirit and an openness to the forces which create and uphold life.”

We look to science to inspire some transcending mystery and wonder – and scientists themselves often feel a sense of mystery and wonder evoked by their explorations – but if they speak of it, they are then speaking not as scientists but as simple human beings.

Second: meaning. The fourth principle of Unitarian Universalism declares our "covenant to affirm and promote a free and responsible search for truth and meaning." Science gives us our best current guess about what is true about the way our world may operate in predictable ways – while teaching, also, a humility of understanding that no truth is final and settled. But meaning – what science’s findings mean for who we are, for the ethics and values that guide our life, for the purposes we may construct for being alive – that is beyond the purview of science itself. We can use scientific findings in the construction of meaning of our lives, but that construction is not itself science’s job.

Science inspires our spiritual lives the way science may inspire poetry. Poets draw on science as Whitman did when he wrote: “Every atom belonging to me as good belongs to you.” As spiritual people -- which is to say, people confronting transcendent mystery and wonder and seeking the meaning of and to our lives -- we draw on science in the way poets sometimes do.

And we ask: What is our place in the grand order of things? For instance, are we alone in the universe?

There are an estimated 100 billion stars in the Milky Way galaxy. If we are very generous and assume 10 planets per star, that gives us a trillion planets in our galaxy. And there are perhaps about 200 billion galaxies. Surely in all that vastness this pale blue dot we call Earth can’t be the only place where life appeared.

Well, let’s think through what the barriers are to the development of life. First, habitability. A habitable planet would be one with liquid water and most of the planets out there are either too hot or too cold. A very rough but plausible estimate would be one in a thousand planets are habitable. If one in a thousand are habitable, then 1 trillion planets means 1 billion habitable planets out there.

The next barrier is stability: it has to have a climate that stays benign over eons. It’s quite difficult to get that much stability because astronomical forces tend to push a planet towards freezing or frying. Our moon – unusually large for a planet our size, and just the right distance away -- gives Earth a stable axial tilt and a slow rotation rate – which helps us have a more-or-less stable climate. Maybe one in a thousand planets in the habitable zone have long-term climate stability. Now the billion planets is down to a million.

As scientist and writer Stephen Webb looks at the remaining barriers to the sort of sophisticated technological life that humans have developed on Earth, he continues to use the very rough guess of about one planet in a thousand making it through each barrier. He says:

“Life must start -- the million becomes a thousand. Complex life forms must arise -- the thousand becomes one. Sophisticated tool use must develop -- that's one planet in a thousand galaxies. To understand the universe, they'll have to develop the techniques of science and mathematics -- that's one planet in a million galaxies. To reach the stars, they'll have to be social creatures, capable of discussing abstract concepts with each other using complex grammar -- one planet in a billion galaxies. And they have to avoid disaster -- not just self-inflicted but from the skies, too. That planet around Proxima Centauri, last year it got blasted by a flare. One planet in a trillion galaxies.” ("Where Are All the Aliens?" 2018)

But our best guess is that there probably are only 200 billion galaxies. So, Stephen Webb concludes, “I think we’re alone.”

This is a rather disappointing conclusion. I love to imagine other star-faring civilizations out there – but as best we can guess, the probability of that is, sadly, low. Very simple life, though, according to Webb’s rough estimations, may well be on about a 1,000 planets in our galaxy alone – but it’ll be single-celled prokaryotes.

Prokaryotes may have started here on Earth as soon as 3.5 billion years ago. But the jump from prokaryotic life to eukaryotic is a huge jump. Stephen Webb simplifies his calculation by assuming that each of the successive barriers he lists is cleared by one out of every thousand planets that had cleared the previous stages. But from what I’ve gathered, it’s really that jump from prokaryotic to eukaryotic that’s the big one.

As Ed Yong writes,

“For roughly the first 2.5 billion years of life on Earth, bacteria and archaea [the two forms of single-celled prokaryotes] charted largely separate evolutionary courses. Then, on one fateful occasion, a bacterium somehow merged with an archaeon, losing its free-living existence and become entrapped forever within its new host. That is how many scientists believe eukaryotes came to be. It’s our creation story: two great domains of life merging to create a third, in the greatest symbiosis of all time. The archaeon provided the chassis of the eukaryotic cell while the bacterium eventually transformed into the mitochondria. All eukaryotes descend from that fateful union.” (I Contain Multitudes 9)

Eukaryotes include all the animals, plants, fungi, and algae. Thus, every animal, plant, fungus, and algae emerged from that one highly improbable fluke. An archaeon absorbed a bacteria and somehow they both survived it, and lived on as a conjoined organism. It was still single-celled, at first, but now it was a cell with a nucleus, surrounded by mitochondria, each with its own distinct DNA. This changed everything. The bacteria part, the mitochondria, provided an extra source of energy, allowing cells to get bigger and become more complex.

“There’s a huge void between the simpler cells of bacteria and archaea and the more complex ones of eukaryotes, and life has managed to cross that void exactly once in four billion years. Since then, the countless bacteria and archaea in the world, all evolving at breakneck speed, have never again managed to produce a eukaryote. How could that possibly be? Other complex structures, from eyes to armor to many-celled bodies, have evolved on many independent occasions, but the eukaryotic cell is a one-off innovation. That’s because, as [biochemists] argue, the merger that created it – the one between an archaeon and a bacterium – was so breathtakingly improbable that it has never been duplicated, or at least never with success.” (I Contain Multitudes 9-10)

Once – in four billion years. Scientists in laboratories haven’t been able to come close to getting an archaeon to absorb a bacterium and have them survive together – yet somehow it happened.

We’ll pick up from there in part 2.

To part 2

The Terrible, Violent, Beautiful, Gracious Jungle

Spirituality of Evolution, part 3

That the mix of competition and cooperation happened to produce humans is, I mentioned, a cosmic accident. That’s a lesson in humility. That we could readily be replaced is another lesson in humility.

“Some zoologists suspect that chimps and bonobos have long been ‘held back’ by the presence of humans – kept from moving out of the jungle onto grasslands and, more generally, from filling the human niche” (Wright, Nonzero, 292)

So if all humans suddenly vanished today, the chimps would Nash-ramble out into the savanna, start spending more of their time walking upright, which would conduce to the voice box dropping down in the throat, which would allow production of more subtle vocal sounds, which, in combination with the positive feedback loop they already have for increased political savvy, would cause the use of those subtle distinctions in vocal sound in a more complex symbolic language. If some virus wipes out all the humans but not the chimps, probably in about a couple million years or so, we’ll be back – that is, a species very like humans: five or six feet tall, with armpits, bad jokes, spectator sports, musical instruments, and so on.

How’s that for a story to give us a sense of our place in the scheme of things? Of course, the chimps are already so much like us. What if all the apes, or even all the primates, or, heck, let’s say all the mammals suddenly disappeared from earth? High levels of intelligence – that is, behavioral flexibility made possible by larger brain-to-body-size ratios – would probably emerge again.

“Toward the end of the age of dinosaurs – just before they ran into their epoch ending piece of bad luck [when a comet or asteroid struck earth and caused massive climate change that wiped them out] – a number of advanced species had appeared, with brain-to-body ratios as high as those of some modern mammals. It now looks as if some of the smarter dinosaurs could stand up and use grasping forepaws. And some may have been warm-blooded and nurtured their young. Who knows? Give them another 100 million years and their offspring might be riding on jumbo jets” (Wright, Nonzero, 293)

-- and arguing over whether to teach evolution in their schools.

Or maybe they wouldn’t. How any given species will go is a highly contingent matter. Yet a level of intelligence – that is, behavioral flexibility – comparable to what humans have is no fluke. “Given long enough, it was very, very likely to evolve.” (Wright 276)

We -- we homo sapiens -- aren’t necessary. Try holding that awareness in your consciousness throughout your day. Remembering this puts the ego's preoccupations in a wider context, and invites us into that wider perspective. Cultivating continual remembrance of non-necessity is a spiritual practice – grounded in what we learn from science.

The evolution story evokes simultaneously a pride and a humility: we are the universe playing itself out – the grand product of the grandest possible creator. At the same time, if we humans weren’t around, the complexity and flexibility of our intellect would simply appear elsewhere. It is a story of nature red in tooth and claw – ruthless, heartless competition forming the conditions for gradually increasing cooperation to form more complex, more beautiful, coalitions of cells, and then coalitions of individuals, to produce wonders that never would have appeared had life been easy.

The moral of the story is the ultimate moral of many spiritual stories: there is irreconcilable tragedy within a basic goodness of reality. The fundamental beauty of the whole somehow emerges from billions of incidents of vicious ugliness. It’s a story of interconnection – for there is ultimately nothing that separates us from the other animals, other life, or from the earth itself. A little more of this, a little less of that – no barriers.

It’s a story that evokes depths of gratitude; wonder and awe. It’s a story of faith, because it tells us there are forces out there that we can trust – that we don’t have to carry all the world’s burdens ourselves. There are much more powerful forces at work out there, and they are slowly, slowly, pushing for ever-greater levels of cooperation and harmony. We are borne aloft by that grace.

Yes, it’s a jungle out there. For that we can be grateful. We -- whether "we" means homo sapiens or "we" means some species with the behavioral flexibility necessary for highly abstract symbolic language and elaborate structures and mechanisms of social organization -- wouldn’t be here if it weren’t a terrible, violent, beautiful and gracious jungle.

* * *
This is part 3 of 3 of "Spirituality of Evolution"
See also
Part 1: Our Best Myth
Part 2: Competition and Cooperation

Competition and Cooperation

Spirituality of Evolution, part 2

Evolution doesn't always tend toward greater complexity. When it does, complexity emerges from two powerful forces: competition and cooperation.

Number one: competition. Various “arms races” appear in nature. Consider the beetle – and remember we have a common ancestor with them, too. When beetles first came along, there weren’t any animals specifically adapted to eat them. After a while, “various animals did acquire, by natural selection, the means to kill and eat” beetles. This spurred a response. The bombardier beetle is able to squirt out a scalding chemical mix upon would-be diners. This prompts beetle predators to adapt accordingly. Skunks and one species of mice “have evolved specialized innate behavior patterns that cause the spray to be discharged harmlessly, and they can then eat the beetles.”

This sort of arms race among species drives them toward complexity. “In North America, the ‘relative brain size’ of carnivorous mammals – brain size corrected for body size – showed a strong tendency to grow over time. And so did the relative brain size of the herbivorous mammals that were their prey.” (Wright, Nonzero, 270) As the predators got smarter, the prey had to get smarter too to find ways of eluding capture, and as the prey got smarter, the predators had to get smarter still to keep on outsmarting them. It was an arms race of brain power that drove toward the greater complexity represented by those relatively bigger brains.

Besides arms races between species, there are arms races within a given species.

“The male chimps, it turns out, spend lots of time scheming to top each other. They form coalitions that, on attaining political dominance, get special sexual access to ovulating females – at the great Darwinian expense of less successful coalitions. So males with genes conducive to political savviness should on average get the most genes into the next generation, raising the average level of savviness. And the savvier the average chimp, the savvier chimps have to be to excel in the next round. And so on: an arms race in savviness – that is, an arms race in behavioral flexibility. There’s little doubt that this dynamic has helped make chimps as smart as they are, and there’s no clear reason why the process should stop where it is now.” (271)

Meanwhile, the female chimps have their own selective pressure to develop political savviness. Female savviness increases the prospects for their young to survive. Competition pushes species toward more behavioral flexibility – more complexity.

Number two: cooperation. Cooperation can benefit both parties, but if you’re premature in offering your cooperation, it’s disastrous. You get taken advantage of: left with nothing, or eaten. For a cell, or something even simpler, such as an autocatalytic protein, payoff is measured only in terms of how many replications of yourself will persist through how long a time. Entering a cooperative relationship is risky. But under the right conditions, it improves your chances of replicating.

Mathematician John Nash (portrayed by Russell Crowe in the 2001 movie, “A Beautiful Mind”), established the mathematics of cooperative strategies. In their blind, stumbling way genes come to pursue strategies without thinking about the goal. Over time, natural selection preserves the strategies that lead to the most payoff – the most replications over the longest period of time – and those are just the strategies that Nash’s mathematics tells us would necessarily produce the most payoff.

Sooner or later, given enough encounters, the mitochondria’s precursor and the nucleus’ precursor are going to figure out how to cooperate to create the nucleated cell. Then these more complex nucleated cells are going to work out schemes of cooperation to form multi-celled organisms. Then those multi-celled organisms are going to come to take in more and more different cells, each taking on more and more highly specialized functions – all as strategies for giving themselves more payoff, more replication.

It takes an awful long time for dumb cells to stumble blindly onto the cooperative strategies that John Nash proved do, in fact, most improve their odds. It takes billions of years. The vastness of the time scale alone induces awe and wonder. And there’s something beautiful about that slow, slow, slow, incredibly patient unfolding of life. Frankly, a story of creation in six days feels spiritually short-changing.

Creation ambles and rambles, moving in no straight line, going down a lot of dead ends, gradually working out ways to overcome the barriers to cooperation. There is indeed an inexorable logic of cooperation pulling alongside the push of competition. The social species – whether humans or ants -- have hit upon ways to utilize Nash's equations. We are, you could say, the Nash ramblers.

The same logic that leads cells to cooperate to create a larger organism eventually leads individuals (in some species) to cooperate to form a larger organism called "society." The need for one group to compete with another puts a premium on cooperation among the members of the group -- and better cooperation within groups intensifies the competition between groups. Cooperation works, we might say, “in harmony” with competition, like chimps forming coalitions to compete with other coalitions.

* * *
This is part 2 of 3 of "Spirituality of Evolution"
See also
Part 1: Our Best Myth
Part 3: The Terrible, Violent, Beautiful, Gracious Jungle

Our Best Myth

Spirituality of Evolution, part 1

Creation stories of the origin and beginning of the world have the spiritual function of situating us: giving us a sense of place and belonging in this world. Creation stories -- such as Genesis 1 or the thousands of other creation stories among human cultures -- awaken our spirits, arouse us to awe and gratitude, show us that we are each more than merely our ego defenses. What’s your creation story, your origin myth?

For most of us, our creation myth is the one we gather from science. "The epic of evolution," wrote biologist E.O. Wilson, "is probably the best myth we will ever have."

Figures such as Lao-Tzu and Buddha and Jesus and St. Francis show us that you don’t have to have modern science’s stories in order to perceive the intrinsic beauty, goodness, and interconnection of things – at least, they didn’t. Buddha and Jesus didn’t need the scientific knowledge that every breath of air they took contained molecules present at the origin of the universe, that our planet and our bodies are composed of the dust of stars, that sea turtles and humans share a common ancestor, that 98.4 percent of our DNA is the same as a chimpanzee’s, or that about 50 percent of our DNA is the same as a banana’s. But if knowing that helps us awaken to awe -- and thus to beauty -- and thus to gratitude -- and thus to compassion -- then let’s squeeze those scientific findings for all the spiritual juice we can. Particularly for us Unitarian Universalists -- we embrace the project of using scientific findings within a spiritually satisfying story.

So today I want to share some of the wonder, and the grace, and the mystery of our story. The crux of our story is: Complexity builds up from simplicity. Life is an emergent property: it emerges from billions of lifeless mechanical processes all going on together. Mind is an emergent property: it emerges from billions of mindless reactions all going on together.

Species evolution is not a linear picture, a straight line of development. Instead, we see a tree of life, starting at a single point and branching off into the various species. There are billions of branches on that tree. The vast majority of them terminate before reaching the present. And there we are, we homo sapiens, at the tip-end of one twig. Once you see how the process works, then you see that process isn’t aimed at any of the billions of species it has produced. It’s just algorithms cranking away.

This nonlinear picture of a tree of life spreading, spreading, spreading, means that evolution has no direction toward any one particular species – or even any one particular genus or order or class. Rather, evolution is heading in billions of directions all at once.

The common ancestor of humans and chimps lived about 7 million years; the common ancestor of humans, chimps, and gorillas, about 10 million years ago; and the common ancestor of humans, chimps, gorillas, and orangutans, about 14 million years ago. This means that we are more closely related to chimps than we are to gorillas – and it also means that chimps are more closely related to us than they are to gorillas – they are, in fact, exactly as far removed from gorillas as we are.

If the tree is a good-sized oak tree, then our twig goes back only about an inch before reaching the point where the twig leading back out to the chimps branches off. That’s our place in the grand scheme of things: on the chimpanzee twig.

Our origin myth comes from science, yet is spiritually relevant, for it is a story of interconnection. It’s a story that shows us to be the product of grand, noble and creative forces beyond our control -- and also shows us to be the recipient of grace – that is, of gifts that we have done nothing to deserve.

This tree of life did not emerge for the purpose of producing a twig of humans or human-like creatures. If you went back in time 2 billion years and started life on Earth from scratch all over again, the chances that you would ever get a primate, let alone a human, are vanishingly small.

Humanity is a cosmic accident. It’s a mystery, a wonder, and a grace that we are here at all. The general tendency that some of the twigs on that tree will get more and more complex over the eons, however, is no accident.

It’s true: Not all the branches head toward complexity. Some branches stay put. “Bacteria showed up billions of years ago, and there’s a lot of them still around, evincing no aspiration to climb higher on the tree of life” (Wright, Nonzero, 267). The most plentiful life form on the planet, both numerically and in sheer pounds, is just as simple now as it was two billion years ago.

Meanwhile, other species have gotten less complex through evolution – because the costs of maintaining a complex feature became greater than the advantages. For example, species that have moved into environments of total darkness have gradually lost complexity in their eyes and optic nerves, sometimes without any increased complexity in other ways.

Evolution doesn’t drive toward complexity unless it has to, and it often doesn’t have to.

NEXT: The Conditions that Compel Complexity

* * *
This is part 1 of 3 of "Spirituality of Evolution"
See also
Part 2: Competition and Cooperation
Part 3: The Terrible, Violent, Beautiful, Gracious Jungle