Way back in the sixties, Lynn Margulis came up with the theory of endosymbiosis while working as a junior faculty member at Boston University.
In her theory she describes how ancient cells (our ancestors) ‘ingested’ smaller cells and incorporated them into their own selves but instead of digesting them, took on their features and functions. These complex cells (eukaryotes [you really should know this]) are what we are made of today. It was cooperation not competition that fueled evolution.
We live in a biosphere. It functions like a living organism, just as you and I do and this organism exists because of symbiosis.
That bit of good news really should alter your day, at least a little bit. We are taught to see the world as a place to do business, to gain an advantage, to compete for ever diminishing resources, but actually, as it turns out, it’s a great place to cooperate and get along. That’s how we got here, it wasn’t the predators who built the biosphere, it was the cooperators.
Her research was controversial. Nobody wanted to believe it – first because she was a woman and second because it seemed to contradict the Darwinian principle of survival of the fittest. But with the advent of genetic testing in the seventies the evidence became overwhelming.
Endosymbiosis is from the Greek, endon “within”, and biosis “living”, and it’s one of the fundamental principles of life. Chloroplasts for example – that green in the green plants that photosynthesises water and carbon dioxide into fuel, is a cell within a cell, it has its own DNA. When the larger cell divides, it divides too. It’s about the size of bacteria and divides in pretty much the same way. That’s because it once was bacteria, then it became part of a larger cell and eventually an integral part of it. Next thing you know, it’s performing essential functions, the big cell can’t live without it. Here’s how that happened.
Four billion years ago, according to Margulis, the first organisms to rise up and be alive on planet Earth were anaerobic bacteria. Anaerobic means ‘without oxygen’ and there wasn’t any oxygen anyway so it worked out fine. They evolved and diversified for billions of years. Consider that. Thousands of millions of years, morphing and exploring and learning how to survive.
Anyways about 2 1/2 billion years ago some of them developed the ability to harvest energy from the sun and split water, thereby releasing oxygen (photosynthesis). As the oxygen built up in the atmosphere it produced an environment that supported bacteria who could use oxygen in their metabolism. At that point, one of the oxygen-using or aerobic bacterium was engulfed by, or tunneled into, a larger anaerobic cell and became part of it’s cellular machinery. It enabled the larger anaerobic cell to use oxygen and the smaller bacterium was supplied with sugar to eat.
That’s the theory by Lynn Margulis. What began as a mutualistic relationship became, over time an obligate one – neither one could survive without the other, co-dependent, married, with someone. Later, this super-cell got together with a third bacterium – a photosynthetic one – and engulfed it as well, a threesome. These composite cells, according to Margulis, are the ancestors of all of today’s complex cells – ones that contain organelles (small organs).
It was symbiosis that allowed us to transition from the original primitive cells to multi-functional cells capable of building multi-functional organisms. That was my epiphany when I finally understood what her theory implied. And by the way, don’t forget what a theory is, it’s not a hypothesis which is a guess. A theory, like the theory of evolution, is an idea that is supported by large amounts of evidence collected by people called scientists who have diligently investigated it. “An idea that is demonstrably true.” according to the American Heritage Dictionary sitting on my shelf.
Of course predation and natural selection shapes our world too, but not to the extent that symbiosis does. If dog eat dog and survival of the fittest were the sole engine driving evolution then there wouldn’t be millions of species on this planet, there would be a lot fewer. A lot, lot fewer because everybody would be eating everybody else. That’s why the proportion between herbivores and predators is like 1,000 to 1 in favor of the herbivores. Ask the wildebeest as they cross the Mara river in Africa on their yearly migration. The crocs are waiting for them but they jump in anyway. It’s 1,000 to 1. Cooperation.
How we got so confused and lost the thread that the other creatures seem to know intuitively, I’m not sure. The examples of symbiosis are almost endless. Our bodies contain trillions of microbes that are given free room and board in exchange for helping us digest our food and also with our immune system. Trees breathe out, we breathe in. The trees don’t want oxygen – we do, we don’t want carbon dioxide – they do. The roots of plants collaborate with fungi, they share their sugar (which fungi can’t make) and the fungi increase the amount of water and nutrients the roots can absorb.
Everyone seems to get it, pretty much, except for us. We still believe in domination and control. Force our way to success. Make it happen. Damn the torpedoes. Start a war if they don’t see it our way. Blast them to smithereens. There are no winners if there are no losers.
All that is wrong, according to Mother Nature, who has been doing this a lot longer than we have. It was her wisdom that guided the development of the biosphere into the highly diverse, interconnected world that it is, not our wisdom.
Another way to say it is teamwork – a sports analogy perhaps.
As Lynn Margulis argues “Natural selection eliminates and maybe maintains, but it doesn’t create”. In her view, it’s symbiosis that is the major driver of evolutionary change.