Fossils, Microbes, and King Kong

Seeing may not always mean believing, but it helps. Especially when the object is big, important, and embedded in a good story. People who might otherwise doubt the reality of dinosaurs nonetheless have the bones and the movies to help persuade them.  As do those who may still doubt our descent from apes. The story of King King may not convince them, but it makes an argument: the giant reptiles are followed by the giant ape who succumbs to a woman and to the modern city. Popular culture loves fossils, giants, and a tragic romance

The trouble is that what we think of as fossils—old bones, mosquitoes trapped in amber, hardened bits of plants—date back no more than 600 million years. That leaves three billion more years before that, six times further into the past, with no familiar evidence to vouch for it. For there were no animals or plants during those billions. There were only microbes, single cells reproducing, clumping together sometimes, like their descendants today in our gut. Little wonder that those eons are never the backdrop for any saga of the bacteria and archaea, No bones from which to reconstruct giants, no fossils to serve as relics to fire the imagination.

Or almost none.

Stromatolites in Australia, probably looking much as they did 3.5 billion years ago. (www2.estrellamountain.edu)

U Microfossils from 3.5 billion years ago (www2.estrellamountain.edu)

 

 

 

 

 

 

 

Start by searching for the oldest rocks. Try Australia, Greenland, or South Africa to find the ones that formed four billion years ago. Slice them thin, put them under a microscope, look for microfossils, tiny creatures’ cell walls that have mineralized into tough material. And look for chemical smears of carbon or the products of the earliest photosynthesis.

Elsewhere look for petrified stromatolites, the layered habitats of colonies of bacteria that filtered sea water for nutrients as far back as 3.5 billion years.

Or look for bands of rust in ancient rocks. Such rust means iron and oxygen, abundant oxygen given off by bacteria as a waste product, enough of it two billion years ago to poison the atmosphere for bacteria that couldn’t tolerate it and then make it a necessity for those microbes that could.

banded iron (britanica.com)

Banded iron (britannica.com)

 

 

 

 

 

 

But could the tiny remains and the odd colors and chemicals that you might find, ancient though they are, actually become the stuff of museum exhibits and monster movies? Could they find their place in popular culture as both entertainment and subtle education, as dinosaurs and apes have?

I think so. It’s not difficult to imagine exhibits of interactive, oversized ancient microbes. Or Hollywood dramas about invasive bacteria from a billion years ago, defeated in the nick of time by oxygen saturation while the heroic Caltech professor of Biogeochemistry (an actual field) explains that the godzillas of 200 million years ago were softies compared to the early microbes that thrived in volcanic vents.

Then our sense of the marvels of our ancestors would reach back through the full history of life.

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 
(wikipedia)

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 (www.kvkcard.org)

(www.kvkcard.org)

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.