Chapter 1: The New Biology
25 - We Contain Multitudes
In only a few decades, the staid world of biology had become a wonderland of fantastic processes and effects. And there was more to come. As one scientist put it, “What we call organisms are themselves communities of previously autonomous creatures that have become integrated into higher-level functional units.”
The classic example of that is a one-celled creature called a slime mold. When food is scarce, thousands of individual mold cells mass together to form a larger body that “slimes” across the ground in search of greener pastures. Eventually the collected mass of cells differentiates into two tiers, a base and a “fruiting body,” which then bursts, scattering spores for new generations.
Closer to home is the groundbreaking research of the cell biologist Lynn Margulis. Working in the mid-sixties, Margulis had pulled together a number of separate strands in developing a radical new theory of how we came to be.
She focused on cell structures called mitochondria, the power plants for cells in higher life forms. Like every other living thing, we’re powered by a slow chemical “fire,” which burns as long as we’re alive. In us that fire is fueled by hydrogen extracted from fats and, more readily, from carbohydrates—sugars—in a complex process involving oxygen and other factors. It’s why athletes practice carbo-loading before a contest, and why eating sweets will bring a familiar surge of energy. Mitochondria—vast numbers of which live in every cell in our bodies—are at the heart of the process.
In 1963, it had been discovered that mitochondria have their own genes. That led Margulis to suggest that somewhere back in the mists of time, mitochondria were free-roaming bacteria that somehow took up residence inside larger cells. Those new boarders, she said, received protection and greater mobility while paying the rent with the excess energy they gave off. When the relationship proved stable, the two types coevolved into one symbiotic unit. From that partnership came an ambitious new cell that would, over the course of time, become the basic building block for complex life forms—from frogs, blue jays, and roses to writers and readers of books.
The science establishment welcomed that thought with a collective cold shoulder. Margulis sent her paper to more than a dozen journals before it was accepted. But she had the last word. Her symbiogenesis is now taught in standard textbooks and considered a seminal insight. In fact, today it’s widely accepted that at least two structures in our cells originated this way, and she suspects more.
As Margulis sees it, the great source of separate species isn’t that of new types branching off from a single ancestor. Rather, she says, the great transformations in evolution occur in just the opposite way—through mergers as separate species converge to form a greater whole. This means, in her words, that “biologists must begin thinking of the cell as a complex community.” Or, as the astrophysicist Carl Sagan put it, “We are not single organisms but an array of about ten trillion beings, and not all of the same kind.”
Taken together with other work now being done, this paints a picture of us as dynamic self-organizing patterns swimming upstream into a current of energy. We use that energy to cycle matter through our systems, pulsing it into ecologies of internal life forms that are moving as we move, feeling as we feel, and continually burning with a slow cold flame.
