Visualizing Evolutional Change

Many people have a hard time visualizing the change that happens to species over the long time spans of Evolution and this problem tends to hinder understanding. I am often asked when was the first of a new species born, as a kind of chicken-or-the-egg dilemma. In reality, the offspring of any species are always almost identical to their parents and you cannot find the defining "new" generation just as you cannot find the grain of sand that, when added to a pile, makes it into a dune (see Sorites Paradox).

To try to help with the visualization, I have been asking people to think of it in terms of the kind of change we see when watching our children grow up. There are some simplifications involved, and it is a limited analogy, but useful none the less. It goes like this: in the 20 years you watch your child grow from birth to being ready to start the next generation, you know he or she is constantly changing over this 20 x 365.25 x 24 x 60 = 10,519,200 minutes, but it is hard to see it over any short interval.

We know from the fossil record and DNA analysis that we, humans, had a common ancestors with Chimpanzees about 6 million years ago. If we take an average 20 year generation time (was probably less), that gives us 6 million divided by 20 or 300,000 generations. If we divide the number of minutes of child development, above, by the number of generations we get that each generation represents a step analogous to about 35 minutes. Yes, I know the change is not exactly smooth in either case, but on average the change you would expect to see in any generation is about how much you see your child grow in 35 minutes.

Of course the kind of change is not the same, but the total change in species can be argued to be less than the change in an individual from birth to adulthood. The point of the thought experiment is that, in general, Evolution does not need changes big enough for you to see them from one generation to the next in order to accumulate big changes over the time it uses.