Natural Wonders: Diversity and Fertility

“The most impressive aspect of the living world is its diversity. No two individuals in sexually reproducing populations are the same, nor are any two populations, species, or higher taxa [categories of organisms]. Wherever one looks in nature, one finds uniqueness.” So wrote Ernst Mayr in This is Biology, published in 1997.

Grains of sand under an electron microscope (wikipedia)

Grains of sand 

This was, to an extent, a new idea to me. Clearly, each species is different from the next, since that is how biologists organize species. But I had not fully absorbed the notion that every single organism, if it reproduces in pairs, is different from every other in its species. Every individual grass plant, every tree, every insect, every ant is as different from another as you and I are. Why? As Mayr explains, diversity ensures that some individuals will fit the environment, that as the environment weeds out some versions, others will survive.

But what about the diversity in the non-biological, inanimate world? To most people, “nature” includes not only living things but also rocks, water, air, light and other forces and materials. Aren’t they unique in their own ways? Snowflakes are all famously different. The clouds are constantly changing. So is the surface of the ocean. Air flows and spins. It’s a good bet that every asteroid, planets and star is different from another. The same probably goes for each individual rock and grain of sand. The molecular make-up of all of these may be more consistent than that of the DNA in plants and animals, but still, looking out over the dessert, the ocean, or the skies, we certainly see diversity in shape, motion, color and light.

A powerful statement of a portion of this variety is Pied Beauty, a poem by the 19th century religious poet Gerard Manly Hopkins. (Pied means “having two or more colors.”)

"rose-moles all in stipple upon trout"  (

“rose-moles all in stipple upon trout”

Glory be to God for dappled things—
For skies of couple-colour as a brinded cow;
For rose-moles all in stipple upon trout that swim;
Fresh-firecoal chestnut-falls; finches’ wings;
Landscape plotted and pieced—fold, fallow, and plough;
And all trades, their gear and tackle and trim.

All things counter, original, spare, strange;
Whatever is fickle, freckled (who knows how?)
With swift, slow; sweet, sour; a dazzle, dim;
He fathers-forth whose beauty is past change:
Praise him.

Though I don’t share the theism, I understand the awe. But despite Hopkins, I think the diversity of living things does “impress” us, as Mayr wrote, in a distinct way. Wind, water, clouds, rock, and the stars amaze us more by their colors , patterns, size, or motion than by their uniqueness. Perhaps one reason that living things are impressive is that their diversity is amplified by their fertility. The volume of life is massive and always on the verge of becoming more so. We see this burgeoning almost everywhere—in the weed-strewn field, in the vegetation in the area inside a curving highway ramp, among the trees at the backs of backyards, among the bugs and birds that swarm, surviving cold and drought, cracking concrete. In Origin of Species, Darwin wrote, “There is no exception to the rule that every organic being naturally increases at so high a rate, that if not destroyed, the earth would soon be covered by the progeny of a single pair.”

It’s conceivable that such prolific progeny could all be the same—if their progenitor was a bacterium, for example—but in fact, as the offspring of a pair, all those earth-covering descendants would be at least slightly different. Diversity is the music, but fertility is the amplifier. It’s the combination that gets our attention. And we are not remote observers. We too are products of that diversity and fertility. We are notes in the music, and instruments in the orchestra.

Diversity and fertility in grass (


The Music Man

Recently I stopped by a music store in town to buy banjo strings. I hadn’t been in the store for at least ten years. I remembered it as a bustling hive of kids and grown-ups trying out guitars, pianos, clarinets; browsing through racks of sheet music and instruction books; going in and out of the back rooms for lessons. This time, it was almost empty—partly the result of the guitar mega-store that had opened on the highway.

What had also changed was the owner, whom I’ll call the music man. He had slowed, acquired a tremor, and lost the steadiness of his speech. To me the change in him, along with the decline in his business, was wrenching, a physical shock. I had expected, without knowing it, that he and his store had remained and would remain the lively hub that I had known. As I left the store I anguished over what the music man’s life had felt like over the last few years. What had been the satisfaction, the worth of it all, as he became ill and his business dropped off? In life, did aspiration and effort always lose out this way to decay? Though I’m in relatively good health, I knew I was asking about myself as well.

But such spasms of pity are distortions of sorts. My sorrow for the music man was based on a very limited view. I had no way of knowing how he saw himself. He had had many years of teaching music to people of all ages, a legacy to be proud of, though whether he was or not I don’t know. And he had music itself as a constant source of joy, presumably. Human sympathy often overgeneralizes. When we feel sad or compassionate for someone or for a group, we easily forget to ask about their ordinary pleasures— in family, community, nature, imagination, music. Sympathy can turn patronizing. I had fallen part way into that trap.

The music man who lives happily ever after.  (

The music man who lives happily ever after.

Still, I couldn’t put down the question that the music man had handed me: what is the value, the worth, of the arc of our lives? Our inner voice, the way we talk to ourselves about ourselves, prompts us to feel that we matter. Do we? There are many responses to that question—lessons about change, the illusory self, and larger realities, and in this blog I describe my own beliefs. But they are all stymied for a moment when we encounter someone who, like a mirror, reflects back at us the starkness of the passage of time and the frailty of joy.

There is another “Music Man.” The 1950s stage musical and film of that name describes the charming con man Harold Hill who arrives in an Iowa town to sell musical instruments and uniforms for the kids with the promise that he will teach them to play and will organize a band. Hill falls in love with the town librarian, who knows he is a fraud, keeps the secret to herself, and loves him anyway. Just when Hill, exposed by someone else, is being put in handcuffs, the instruments and uniforms arrive. Quickly the children appear in their uniforms, magically playing a Beethoven minuet haltingly and then, full bore, the rousing finale of “Seventy-six Trombones.” All is forgiven.

“The Music Man” shows another kind of big-picture consolation about time and fate. It is a romanticized version of the Christian response: the sinner is redeemed by love, death is defeated by grace. Perhaps the music man in my town likes this story. But as I see it, much as music itself is most compelling when one person plays it and another listens, our human condition, transient yet often dignified, comes home to us most forcefully when we witness it in another.

Evolution for a Warmer Climate

The climate of the next few centuries “is expected to change 10 to 100 times faster than in the recent geological past.” Slowing this disastrous shift is one struggle. Another is figuring out how to help earth’s organisms to survive it. Humans have long maneuvered evolution to breed plants and animals for their own use. But as the earth grows warmer, understanding and experimenting with how species adapt to change is taking on a more ambitious, long-term purpose.

Animals and plants are responding to current climate changes in two ways. They adjust within the capacity of their DNA—plasticity, as it’s called—and they adapt by changing genetically. They demonstrate plasticity when birds breed and plants flower earlier as spring comes sooner. Animals show flexibility when they migrate towards cooler poles and higher elevations. Many species that scientists had considered doomed have shown greater flexibility than expected, but such plasticity has its limits.

Genetic changes—true evolution—are profound but also less adjustable in the short term. These are changes that can enable a species to resist new diseases and to thrive in new environments. The species that have the best odds for making such  evolutionary leaps are generally those with short lives (and therefore frequent reproduction), many off-spring, genetic diversity, and mobility.

Copepods off the west coast show some flexibility to water temperature but don't migrate enough to make larger genetic adjustments. (

Copepods off the west coast show some flexibility to water temperature but don’t migrate far enough to make larger genetic adjustments.

A case in point: The shrimp-like copepod swims off the west coast all the way from Mexico up to Alaska. That range of water temperatures might suggest that copepods would have no trouble adjusting to warmer water if they needed to. But the local populations are acclimated only to their local temperature and they don’t travel far enough to breed with other copepods that can handle warmer oceans. They are stuck within a limited plasticity.

Purple sea urchins are a different story. They must cope with the increasing acidity in the ocean that is one effect of a warming climate. Like the copepods and temperature, sea urchins in different parts of the ocean tolerate their local acidity. But the sea urchins are better off than the copepods because, essentially, sea urchins are more sociable. They are more likely to migrate, interbreed, and adapt genetically to higher levels of tolerance.

Purple sea urchins move around and intermingle, making them good candidates for genetic changes that will help them tolerate the ocean's rising acidity.  (

Purple sea urchins move around and intermingle, making them good candidates for genetic changes that will help them tolerate the ocean’s rising acidity.

Many species of animals and plants, like the copepods, will be unable to adjust enough to survive. So humans are beginning to step in. Conservation groups are connecting wilderness areas so that migrating species aren’t cut off by highways, cities, suburbs. One example are the Yellowstone to Yukon Conservation Initiative corridors between wild landscapes that run from Yellowstone Park to northern Canada.

In more active interventions, scientists have moved the seeds of trees in order to acclimate them to new environments. Animals too have been transported in order to change their genetic strain (though not yet for climatic reasons). When Florida’s panther population dropped below 30 in the 1990s, eight females that were brought from Texas created enough genetic variation to overcome the effects of inbreeding and multiply the population.

For now, scientists are mostly gathering information. How much can organisms adjust before they die off? Which necessary changes are genetic and therefore relatively slow? And—a devilish question— which species should we try hardest to save? The ones most at risk? Or those most likely to survive? The popular animals like lions and elephants? The ones that carry out key functions in the survival of other species, like bees?

Such interventions and assessments reassure and unnerve me at the same time. As the climate worsens and the urgency grows, as the effort to save species scales up, imagine the conflicts that will emerge. We have seen the debates over GMOs, carbon capping, sea coast construction. Imagine the political feuds and violence of the future when temperature and rainfall have shifted so much that it’s time to commandeer new land for farming, to organize globally to select animals and plants for survival, to abandon regions that are turning to desert and floodplain, to allocate water to some communities of species and not others. As the stakes get higher, the human role on the planet will grow more urgent and potentially more dangerous.