“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.
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.”)
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:
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.