Early Cells Engulfed Tiny Creatures!

The progress of Nature’s Continuing Creation depends on the processes of competition and cooperation.  Cooperation in Nature includes colonization and specialization of functions.  An early form of colonization is symbiosis — for example, bees and flowering plants help each other through symbiosis.  But the earliest type of symbiosis may have been endosymbiosis — When one single-celled organism enfolds a single-celled creature of another species and uses the captive’s cellular machinery to its own advantage, usually while sharing one or more of its own advantages (e.g., protection and food) with the “captive.”  — J.X. Mason

Below is my favorite passage from Dr. Lewis Thomas’ classic book, “The Lives of a Cell: Notes of a Biology Watcher” — 

“A good case can be made for our nonexistence as entities.  We are not made up, as we had always supposed, of successively enriched packets of our own parts. We are shared, rented, occupied…

“At the interior of our cells, driving them, providing the oxidative energy that sends us out for the improvement of each shining day, are the mitochondria, and in a strict sense, they are not ours. They turn out to be little separate creatures — probably primitive bacteria that swam into ancestral precursors of our cells and stayed there.  Ever since, they have maintained themselves and their ways, replicating in their own fashion, privately, with their own DNA and RNA quite different from ours…

“They are as much symbionts as the bacteria in the roots of beans.  Without mitochondria and the ribosomes inside them, we would not move a muscle, drum a finger, or think a thought.  The mitochondria are stable and responsible lodgers, and I choose to trust them… [Ribosomes are tiny molecular “machines” that link amino acids together to form proteins.]

“But what of the other little animals, similarly established in my cells, sorting and balancing me, clustering me together?  My centrioles, basal bodies, and probably a good many other more obscure tiny beings at work inside my cells, each with its own special genome, are as foreign, and as essential, as aphids in anthills [several species of ants capture and “farm” aphids for their honeydew secretions]…

“My cells are no longer the pure line entities I was raised with; they are ecosystems more complex than Jamaica Bay.  I like to think that they work in my interest, that each breath they draw for me, but perhaps it is they who walk through the local park in the early morning, sensing my senses, listening to my music, thinking my thoughts…

“I am consoled, somewhat, by the thought that the green plants are in the same fix. They could not be plants, or green, without their chloroplasts, which run the photosynthetic enterprise and generate oxygen for the rest of us.  As it turns out, chloroplasts are also separate creatures with their own genomes, speaking their own language.”  — Lewis Thomas