It’s Diversity All the Way Down

“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 

Part of his statement was a new idea to me. Clearly each species differs from the next. But I had not fully absorbed the notion that every organism, if it reproduces in pairs, is different from every other individual in its species. (Single-cell organisms like bacteria that divide into identical clones are the exception.) Every individual grass plant, every fish, every pure-bred dog, every ant is as different from another of its species as two human neighbors are. And, as Mayr adds, that makes uniqueness the order of the day.

But what about  diversity and uniqueness in the non-biological, inanimate world? “Nature” includes not only living things but also rocks, water, air, light and other forces and materials. They seem to be unique in their own ways. Snowflakes are famously singular. Clouds change constantly. So does the surface of the ocean. Air flows and spins. I’m pretty sure I’ve never seen two rocks that are identical. It’s a good bet that every asteroid, planet and star is different from others. Looking out over the desert, the ocean, or the skies, we always witness diversity in shape, motion, color and light if we look closely enough.

Diversity and fertility in grass (


Still, Mayr seems right that the diversity of living things  “impresses” us in a distinct way. Each organism succeeds at being alive, yet does so in a slightly different way from the others.

Moreover,  that booming variety, that hedge against species failure, comes on fast and strong. New life thrusts itself at us—in the new baby, in a puppy, among the trees springing up in corners of the yard, in the horde of ants and bees and birds of summer. 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.”

Diversity multiplied by fertility.


People Are Different

One perception of mine that has strengthened over the years is how different people are. When I was young, I thought of these differences mostly because of the difficulties they presented—how to talk to this girl, how to respond to a teacher, how to put up with a tedious relative. But after enough time it’s easier to sit back and enjoy the variations. People are a circus of performances, each of us with different things to say, different knacks and loves, different hostilities and indifferences, different politics, different ideas about big issues. The people we know the best, our closest friends and family, are different from each other in ways that we peer into more and more deeply over time. Even the youngest siblings, peas from the same pod, amaze their parents with their dissimilarity.

British marathoners (

British marathoners

I asked a friend who is a therapist how he kept all his patients straight if he didn’t take notes. He said, “You know a lot of people. Do you ever get them mixed up?” We’re good at keeping people sorted out.  We get along with most of them, we love some, and we try to forgive a few. We all understand that the differences among us are serious business because they determine how our lives will play out, and that how a life plays out will create more differences.

Compared to the richness of differences, the similarities among us sometimes seem few and familiar.  As people like to say, down deep we’re all the same. Our common needs and fears are relatively small in number. They’re emotional and biological.  We learn them profoundly and intensely but narrowly. They do justify the amazing claim that all people are created equal and endowed with the same rights. But day to day our brains track not the sameness among people but our differences as we look for signs of who we might connect to. We start at infancy, reading Mom’s face.

We gave up being identical a couple of billion years ago when our bacterial ancestors ceased cloning themselves and instead began mixing up their DNA through sex. Since then, diversity has been natural selection’s ace in the hole; if one combination of genes proves vulnerable, another might solve the problem. Humans have taken the generating of diversity a step further. In addition to the DNA variations, we have a brain inclined toward language, specialization, and complexity. The result is Nancy, Bill, Brett, Joanne, Florence, Ravi, Mike, Meredith, Doris, Kevin, Sandra….