Size Matters

Small things are difficult to see. The smallest things are difficult even to imagine. We are missing life at its smallest, overlooking living things that came before us and make us possible. We need to look inside the box more appreciatively.

OPEN this terrific graphic from the Genetic Science Learning Center at the University of Utah for a trip into the world of small. Click on the slider, slide it to the right, and zoom in past a sesame seed, past a skin cell, then a blood cell,  a bacterium, all the way down to viruses, molecules, and finally a carbon atom. It’s a wild trip. 

The zoom takes you down into the roots of life. It also takes you back in time. Back billions of years, from complex single-celled creatures and building blocks towards the not–alive viruses that may predate full reproductive life, back to one of the atoms that makes it all possible. Small came first. And life stayed small for a long time.

Then it got bigger. Humans are not only complex but relatively large. Elephants, whales, and trees grow larger than we do, but hundreds of species of everything from dogs to Humans are not only complex but also relatively large. Elephants, whales and trees grow larger than we do, but hundreds of species, from cows to ordinary bushes, come in our size range. Up to a point and with exceptions, a bigger body survives longer.

Perhaps this trend underlies our perceptions of authority and even spirituality. The entities that we worship in any sense of that word are bigger than we are—not only gods but powerful people who seem ‘larger than life,’ or the universe itself, or Nature. They are the somethings–larger than we are often seeking. We grant even big trees and elephants a majesty that we don’t attribute to bushes and mice. Large things, if we think they are friendly, offer inclusion and protection.


But we don’t usually feel that warm about tiny things. That’s partly because we simply can’t see them. I wonder what it would be like if we were able to see individual bacteria, skin cells, the cells in a piece of fruit in the same way that we can easily see even individual blades of grass. Imagine seeing the single–celled creatures floating in the air and in the water and on our skin, on other skins, in our food, in our rooms. Would we feel enveloped by life in the way that we do when walking in a forest or watching flocks of birds? If we could see all those individual cells pumping, crawling, swimming, dividing, could we find our something–larger in those somethings–smaller?

“Your Inner Fish”

Most people accept the idea that we are descended from earlier primates. But descended from fish? That might seem to be a stretch. In Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body (2008), Neil Shubin makes a vivid case. He traces our body parts back to fish and beyond. And he comments passionately on the beauty and unity of life’s development over billions of years.

tiktaalik

Tiktaalik, ready for push-ups–and land
(shubinlab.uchicago.edu

Along the way, Shubin narrates the painstaking detective work of the paleontologist. He weaves the opening chapters around his own years in the barren Arctic as he helped to discover, in 2004, the 375-million-year-old fossil of a missing link between fish and amphibians.

The discovery  of Tiktaalik, Inuit for “large freshwater fish,” was exciting for several reasons:

All fish prior to Tiktaalik have a set of bones that attach the skull to the shoulder, so that every time the animal bends its body, it also bent its head. Tiktaalik is different. The head is completely free of the shoulder. This whole arrangement is shared with amphibians, reptiles, birds, and mammals, including us. The entire shift can be traced to the loss of a few small bones in a fish like Tiktaalik. (p. 26 in the Vintage paperback edition).

Say hello to our neck.

neck

In the middle, Tiktaalik’s new neck.
(avonapbiology.wikispaces.com)

There was another surprise about Tiktaalik. Earlier fish had fins with bones that were the ancestors of our arms and fingers. To these early forearms and fingers Tiktaalik added small bones that were, in fact, the earliest wrists. These crude wrists mean that Tiktaalik, as Shubin puts it, “was capable of doing push-ups….The wrist was able to bend to make the fish’s ‘palm’ lie flat against the ground….Tiktaalik was likely built to navigate the bottom and shallows of streams or ponds, and even to flop around on the mudflats along the banks” (39-40).

So Tiktaalik had fins capable of supporting the body—these were the first limbs for moving on land. Since then, the same structure has appeared in not only the arms, legs, and hands of humans and other mammals but also in the wings and flippers of bats, penguins, birds, and whales. In all these, one bone is attached to the torso (in us, the upper arm bone and the upper leg bone), followed by two bones, followed by little bones (wrists and ankles), followed by smaller fingers and toes.

limb bones

Limb bones from fish to humans
(noreligionblog.wordpress.com)

Shubin’s other chapters trace the development of teeth, heads, noses, eyes, ears, and even bodies themselves, which emerged 3.5 billion years ago. In each chapter at some point, Shubin pauses to explain his appreciation of the patterns he is describing. “Beauty” and “beautiful” are common words in the book. The anatomy of the head “is deeply mesmerizing, in fact, beautiful. One of the joys of science is that, on occasion, we see a pattern that reveals the order in what initially seems chaotic. A jumble becomes part of a simple plan, and you feel you are seeing right through something to find its essence” (82). Echoing Carl Sagan’s thought that “looking at the stars is like looking back in time,” Shubin says the same about the human body. “If you know how to look, our body becomes a time capsule that, when opened, tells of critical moments in the history of our planet and of a distant past in ancient oceans, streams, and forests” (184).

I would guess that many scientists feel the same way about looking into the essences behind the apparent chaos. But not many write about it so well. That’s unfortunate, because I think that if they did, more non-scientists would value what our biological history can tell us about who we are and what our lives mean.