Monday, December 10, 2007

Geologic time scale

I'm not sure that a lot of people understand the incredible amount of time available for the process of natural selection (especially those that think that the Earth is only 6000 years old). The Earth is around 4.5 billion years old, and life began roughly 3.6 billion years ago. That is billion with a 'B.' Ten to the power of 9 (at least here in the US). One thousand million. The fact that the current US national debt is 9 trillion probably doesn't help the general comprehension level. Here is what one billion pennies would look like. I got this from the MegaPenny Project website:

It would take up the space of 5 school buses. Life has been around for at least 18 school buses.

This gives natural selection--the non-random selection of random mutations--an enormous amount of time to occur. If a mutation only has the extremely small one-in-a-million chance of happening in any one year, given a million years it is a virtual certainty. Alternately, if it has a one-in-a-million chance of occurring in any one individual, given a population of a million individuals it is bound to occur in at least one (thanks to Richard Dawkins and E.O. Wilson for those examples). Mutation rates can be much, much faster than that. Beneficial mutations tend to be passed on to offspring, and disadvantageous mutations tend to be weeded out.

Creationists insist that evolution is all chance, and that nothing as complex as X (where X=eye, hand, feather, etc.) could evolve by chance. Natural selection is the opposite of chance. The mutations are chance; the selection is not. The cumulative effects of the non-random selection over this huge amount of time allows the gradual (and sometimes not so gradual) increase in complexity eventually evolving such things as eyes.

As Linus Pauling said, "Science is the search for truth." Unfortunately, he then went on to write rubbish about the benefits of Vitamin C for preventing colds, but that's another blog entry. He was right about science being the search for truth, though.


Kia said...

All that stuff about Vitamin C is rubbish? You mean I've been eating nasty citrus fruit this week and it won't keep me from catching any of the cold viruses going around?

Laurie said...

Not unless your immune system is weakened by scurvy :-)

Laurie said...

Just testing how to do a link in comments. Here is a link to a synopsis of Vitamin C Studies.

Wow. That was a long and torturous route to get it to link.