Life's Most Amazing Invisible Secrets

One of my heroes, evolutionary microbiologist Lynn Margulis, died this past Thanksgiving. She was an amazing lady who was married to Carl Sagan for many years, and partnered with James Lovelock in discovering that the earth is an interconnected living global ecosystem run largely by microbes. She pioneered the theory of symbiogenesis -- that new species are created through symbiotic partnerships.

Her book What is Life? offers stunning insight into the nature and evolution of living systems.

Here are some of her most surprising, and fascinating revelations:

1. Life is a verb

We tend to think of life forms, instead of life flows. But Margulis and Lovelock pushed biologists to realize that life is not confined to the things now called organisms. "Life on earth is more like a verb. It repairs, maintains, re-creates, and outdoes itself."

We are "flowing streams of order, like flames, whirlpools, tornadoes," writes Margulis, "but unlike these other natural flows, we maintain our form, and even better - we spin off new forms to continue the process."

"Life harnesses the universal forces of physics and chemistry by bounding them within cell walls, tissues and organs to create organized flows of energy and matter. Without these vital flows of oxygen, water, and food, living systems can't sustain themselves."

2. Life is made from a few simple Ingredients

"The basic building blocks of life are very common throughout the universe," writes Margulis. Oxygen and hydrogen make our air and water -- the most fundamental things we need to survive. Hydrogen is the most common element in the universe, and also in ourselves. Add carbon, and you've got pretty much everything we breathe, drink, eat, or burn for fuel -- from carbohydrates to hydrocarbons. All with different combinations of 3 common atoms.

"Life takes this matter and organizes and energizes it; drawing elements into itself, and bringing atoms "to life."

3. Life is walking, talking minerals

Life evolved in a complex interaction and exchange with the environment around it. Not only are life's basic chemical compounds found throughout the universe, scientists have recently discovered that life produces over 50 minerals: from shells to kidney stones.

In essence, people are "walking, talking minerals." We concentrate elements of the Earth's crust into "two-legged, upright forms" that wander around, digging, burning, and melting other elements, altering the Earth's surface and atmosphere.

4. Life shapes the earth's surface and atmosphere

In the process of living, billions of tiny creatures create bones and shells which accumulate into entire cliffs and continents. Organic matter makes up oil and coal deposits, limestone cliffs, and coral reefs - literally shaping the continents. Like life itself, the earth's crust, atmosphere and oceans are not static bodies, but a constantly flowing process, interacting and exchanging gases, minerals and molecules.

Since life began, the sun has grown by 30%, but life has maintained steady temperatures on earth. Life has also maintained steady oxygen levels for over 2 billion years, as well as balancing the salinity of the oceans.

So life is a planetary phenomenon, interconnected at both the deepest and highest levels. But the truth is, it's not really the plants and animals doing any of this.

It's the microscopic bacteria inside us.

5. Life is bacteria

A pioneer of evolutionary microbiology, Margulis discovered that the mitochondria inside every living cell are actually separate creatures with their own DNA. This means each cell is actually a complex partnership, a symbiotic relationship that developed billions of years ago.

Bacteria, "our ancient ancestors, and our modern inhabitants, are truly amazing creatures....Barely 1000 times larger than a hydrogen atom, yet more complex than a computer," they literally invented "every major kind of metabolic transformation on the planet."

But that's just the beginning of their amazing abilities. "Bacteria can evolve almost instantaneously by simply swapping genes with any other bacteria they meet. Talk about casual sex!

"Bacteria are the oldest, most diverse, most tenacious, most numerous life forms on earth. They are immortal, and virtually magical -- constantly changing their color, shape and abilities by simply swapping genes."

And oh yes -- there's bacteria inside each of your cells, and you couldn't live without them for a minute. In a very real way, bacteria ARE life. They are the tiny, tenacious, adaptable roots of the entire tree of life.

6. Life is addicted to oxygen

Scientists don't believe life emerged in an oxygen atmosphere. Rather, life created that atmosphere, and has maintained it ever since. The ancient Earth had an atmosphere that was almost entirely carbon dioxide -- like Mars and Venus do today. But early photosynthesizers sucked up all the carbon dioxide, combining it with water to make carbohydrates, and releasing the oxygen into the atmosphere.

Before the oxygen revolution, bacteria were fermenting sugars -- basically making alcohol and drinking that. But burning a sugar molecule with oxygen gives off 18x more energy than fermenting it.

Oxygen is life's energy drink, and we're hooked!

7. Life is community

Fueled up on oxygen, ancient "squirming predators attacked sugar fermenters, and eventually the two were merged into multi-cellular beings..." This means that the ancestors of every plant and animal cell on earth - including ours - were communities - "bacteria that merged to form a new kind of cell."

So not only are individual living cells so tiny we can't see them, these microscopic creatures are themselves communities formed of ancient partnerships with yet smaller creatures.

"Life forms patterns that envelop each other. Fatty molecules form membranes that cycle acids, proteins and nutrients. These living cells form organs which evolve into organisms. Organisms form communities of organisms from hives to tribes, which eventually form whole ecosystems including coral reefs, rainforests and bustling human cities."

You are not so much a single creature as an enormous high-rise, crowded with billions of living cells, each of them growing and reproducing, swapping minerals and nutrients with their neighbors, and continually rebuilding you from the inside out.

Amazingly -- each one of them is awake and aware.

8. Life soaks up experiences and all life "perceives"

Just as living organisms metabolize air, water, and food for energy; they also absorb sense impressions and experiences. "All living beings, not just animals, but plants and microorganisms, perceive. To survive, an organic being must perceive - it must seek, or at least recognize, food and avoid environmental danger."

This means every single living cell is aware of "the world outside [ its ] cell membrane."

9. Life makes meaning

As we perceive our environment, we make patterns. We learn to recognize sounds and shapes, and make sense of the world around us. "Life learned early on to recognize itself," writes Margulis. To survive you need to know what can kill you, what you can eat, and who to have sex with -- in that order.

"We share a common heritage, not only of chemistry but of consciousness," writes Margulis.

The more we make meaning of the world around us, and seek to understand its flows and limits, the better we can gauge our impact on the environment and each other. "All growing populations integrate into the working biosphere or they become extinct."

10. Life flows on

The Beatles were quite right when they sang, "Life flows on within you and without you." Life's forces are universal, and her flows are universal, but her forms are unique. Each one.

So lets appreciate the invisible beings inside us, and the beautiful planet they've helped create for us. Lets acknowledge our responsibility as stewards of this planet and work to live in better harmony with all forms of life. And lets celebrate the scientists whose work gives us a deeper understanding of the amazing world we live in.

(For more about Lynn's work, the good folks at Edge have put together a page of reviews and critiques from her fellow scientists.)