Our Ancestors the Bacteria

Reading time about 90 seconds

Scientists are not yet sure as to where life on Earth first appeared or how it began. The closer they get to the time, some 3-4 Billion years ago, when the first organization of organic molecules became something we would recognize as being alive, the more difficult it is to understand.

The one thing they do know is that our ancestors were single celled organisms best described as primitive bacteria. Yes I said bacteria. I know that a lot of folks argue that we humans are not descended from apes, they're right we aren’t, but the truth for those folks is probably worse. All of us, every living thing on Earth whether plant; animal or insect share a common bacterial ancestor which appeared at least 3.5 billion years ago. They know that because these early bacteria left chemical signs in rocks that old.

These bacteria solved most of the problems of cell chemistry and developed the mechanisms of heredity long before multicellular organisms evolved. By the time they did most of the hard work of living had been done. How did they do it? Well, by trial and error. The things that worked were preserved and the things that didn’t perished. This process did not happen quickly or easily. Countless billions and billions of experiments were made by those primitive bacteria over billions of years. The reason so many tries could be accomplished is because of the rapid rate of reproduction by such simple creatures. Today a bacterium under ideal conditions can produce a new generation every 20 minutes, three each hour, 72 new generations per day and 25,632 per year. Can you imagine how many generations can be produced in 2 billion years? How many experiments can be tried?

So how did these experiments come about? Well, through a thing called mutation. Every time a bacteria or a modern cell divides it copies its DNA and passes along a copy to the new cell or bacteria. Sometimes an error in copying happens and that is passed to the new cell. If this error results in the new cell being better able to survive to reproduce, then it is preserved and passed along to its offspring. If it harms the organism’s chances to live to reproduce then it probably won’t be preserved in the population.

At 3 generations per day for 2 billion years you can see where a lot of errors can be passed along even if the rate at which an error in copying is made happens say once every million generations. That sounds pretty iffy at only one error per million generations, I know. But, we are not just dealing with one bacterium multiplying over the span of 2 billion years, but untold trillions of billons of trillions of bacteria dividing and subject to an error. You can see how over deep time there were many opportunities for copying errors and many, many experiments.

Maybe the lowly bacteria deserves a bit more respect.