What is Life?

What is the simplest life form?

Since the common idea is that all life evolved from one common ancestor, why are there still some life forms that "have not evolved very far?" You can read posts on this forum where people sound like they believe some life forms are "more evolved" than others, whereas every life form has actually been evolving for the same amount of time.

Why are there still single cell organisms? Why haven't they evolved into more complex organisms?

True. If evolution is survival of the fitest (which requires you to reproduce more than others) then we should expect all life forms to evolve to smaller life forms that reproduce quicker. The evolution tree would be upside down. We should all end up bacteria (which currently makes up 80% of all living things).

"Humans have a long life expectancy as a result of being very good at investing resources in their offspring."Actually, humans are not "very good" at evolution. There are currently 5,000,000,000,000,000,000,000,000,000,000 bacteria living on earth (perhaps 80% of all living things) and only about 7,000,000,000 humans living on earth. And I predict that the percentage of bacteria will increase whereas the percentage of humans will decrease. Do you predict the opposite?

"First, evolution is simply change over time."Evolution is not "change over time" but "change by mutation" via Natural Selection.Natural selection is the process by which genetic mutations that enhance reproduction become, and remain, more common in successive generations of a population.We should have expected that simple organisms alive today should have experienced some mutations to change and not remained the same for so long.

Granted, I assumed that the phrase "evolution" on this forum would mean "the theory of evolution".I will restate it...If the theory of evolution is correct, we should have expected that simple organisms alive today should have experienced some mutations to change and not remained the same for so long. 80% of all living things are still single cell organisms.

jar writes: "things both living and non-living become more complex and less complex. There is no directionality."If it is just as likely that things become more complex as it is that things become less complex, then there is no directionality.However, I suspect that we all believe that there is in fact directionality.Evolutionists believe that things become more complex faster than they become less complex, therefore you have a gradual increase in complexity. Things began very simple and are becoming more complex.Creationists believe that things become less complex faster than they become more complex, therefore you have a gradual decline in complexity. Things began very complex and are becoming less complex.

IF the probability that a mutation adds to the genome is exactly the same as the probability that a mutation removes part of the genome, then there will be no directionality.However, evolutionists believe that it is more likely that a mutation will add to the genome which gradually results in more information in the genome. Creationists believe that it is more likely that a mutation will remove part of the genome which gradually results in less information in the genome.