In high school biology class you learned that mitochondria and chloroplasts, which are parts of cells today, were once “most likely” primitive bacterial cells. Though incorporated in cells today, they must have had some initial independence because mitochondria have their own DNA. Somehow and long ago, animal and plant cells engulfed mitochondria and chloroplasts and made them essential. One might hypothesize that in the process other, less useful or more inimical forms of primitive life remained as outcasts rejected by our early cell ancestors.
Maybe the outcasts were eliminated on a world of violent extremes, such as Earth was 3.5 billion years ago. The planet had just come through the heavy bombardment of comets and asteroids as it swept its orbit with an increasingly greater gravitational pull, cleaning its path as it revolved around the sun like some robot sweeper taking care of an apartment floor in the absence of intelligent owners. One of those wandering celestial objects swept up by gravity might have been large enough to blast some of the planet into an orbit around itself—thus the moon.
Yes, Earth was a violent place back then, even without bolide impacts. It was also, by our standards, noxious. The planet’s young surface certainly had a mix of liquids and gases that would be toxic to most of today’s life forms. Can’t imagine living in a world where formaldehyde and ammonia were in the air with sulfur dioxide, acetylene, and carbon dioxide. Can you? Yet, it was in that kind of environment or shortly after that those early cells began to live harmoniously with and eventually become dependent upon self-replicators that are now apparently essential to their functions.
Imagine that! In a noxious and toxic world bombarded by violent intruders from space, cells, mitochondria, and chloroplasts found a way to live together.
Once cells established the symbiotic relationship with mitochondria and chloroplasts, they settled into billions of years of seemingly relative stability. Probably, however, some rejecting and incorporating continued and might even continue today.
I could argue that cells are still involved in the work of rejection, that the stability of cell makeup is one of the reasons that cells are open to attack by modern bacteria and viruses still trying to get inside. Invaders are always at the gates. Cell walls and membranes serve to protect, but they will never be, as the great walls of Troy demonstrate, fully immune from some kind of disruption. Cells have their Trojan horses.
Is there a lesson in this? Is there something we can learn from a tiny cell and its evolution? Is cell evolution an analog of society’s development? Of course, every analogy limps, so comparing the endosymbiotic evolution of cells to societal development fails at some point. We can note, however, that endosymbiotic evolution has provided cells with certain survival advantages. Is that the lesson?
Maybe the outcasts were eliminated on a world of violent extremes, such as Earth was 3.5 billion years ago. The planet had just come through the heavy bombardment of comets and asteroids as it swept its orbit with an increasingly greater gravitational pull, cleaning its path as it revolved around the sun like some robot sweeper taking care of an apartment floor in the absence of intelligent owners. One of those wandering celestial objects swept up by gravity might have been large enough to blast some of the planet into an orbit around itself—thus the moon.
Yes, Earth was a violent place back then, even without bolide impacts. It was also, by our standards, noxious. The planet’s young surface certainly had a mix of liquids and gases that would be toxic to most of today’s life forms. Can’t imagine living in a world where formaldehyde and ammonia were in the air with sulfur dioxide, acetylene, and carbon dioxide. Can you? Yet, it was in that kind of environment or shortly after that those early cells began to live harmoniously with and eventually become dependent upon self-replicators that are now apparently essential to their functions.
Imagine that! In a noxious and toxic world bombarded by violent intruders from space, cells, mitochondria, and chloroplasts found a way to live together.
Once cells established the symbiotic relationship with mitochondria and chloroplasts, they settled into billions of years of seemingly relative stability. Probably, however, some rejecting and incorporating continued and might even continue today.
I could argue that cells are still involved in the work of rejection, that the stability of cell makeup is one of the reasons that cells are open to attack by modern bacteria and viruses still trying to get inside. Invaders are always at the gates. Cell walls and membranes serve to protect, but they will never be, as the great walls of Troy demonstrate, fully immune from some kind of disruption. Cells have their Trojan horses.
Is there a lesson in this? Is there something we can learn from a tiny cell and its evolution? Is cell evolution an analog of society’s development? Of course, every analogy limps, so comparing the endosymbiotic evolution of cells to societal development fails at some point. We can note, however, that endosymbiotic evolution has provided cells with certain survival advantages. Is that the lesson?
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