But is it long enough?


I was talking with my lab mate yesterday, and we came on to the subject of if the Earth is actually old enough to produce an organism as complex as humans.

I should explain something, I am pro evolution, I’ve seen the evidence, there is no doubt in my mind natural selection is the mechanism to produce life’s diversity.  That being said, I am not an atheist, I am a Christian*, so I fall in the theistic evolution camp.  That camp gets a lot of flack, either from the atheists saying we are crappy scientists, or from the creationists saying we are crappy Christians/Muslims/Jews/Flying Spaghetti Monster Worshipers.  Whatever, my religion is only accountable to God, and my science will speak for it self**, fuck em both.

Now that the background is out of the way, we both agreed that the Earth has been around to short to see the diversity we see.  A thought occurred to me, this is quantifiable, so I ran through the numbers.  The Earth is 4.54 billion years old, which means it has seen 1.6571 trillion days, which means it has been around for 39.7704 trillion hours.  E.coli divides at a rate of about once every 20 minutes, mas or menos, which means 3 divisions per hour.  With an error rate of 1/100,000,000, there wold be 1.193 million mutations, and if 1 in 10 of those were beneficial that would mean 119,311 beneficial mutations over the course of many millennium our planet has been existence.

If you alter the numbers to reflect the 3.8 billion years that life has actually been around***, you still end up with a whopping 99,864 beneficial mutations in the last 3.8 billion years.  The human genome has 23,000 functional genes in it.

Now there are many things I am not taking in to account, for instance, a single mutation does not make a new gene.  Also, things such as genetic drift, sexual reproduction, longer generation time as organisms become more complex, and mass extinctions.  I just wanted to run through the numbers quickly, and try to get a number.  Similar to the Drake Equation, doesn’t really tell you anything, but hints at  possibilities.

*not a very good one, I don’t go to church nearly enough and Pam and I are living in sin

**Or it won’t, doesn’t matter to me…

***Apparently magma needs to cool off before microbes can grow, who knew?

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~ by epiphron13 on July 19, 2010.

2 Responses to “But is it long enough?”

  1. But, don’t forget that a lot of organisms share a lot of the same DNA (expanding on improvements takes less time then from starting from scratch again and again…) and don’t forget exponential (logistical?) growth as organisms multiply, specialize and diversify (so the probability of mutations increase too…. and spread out amongst an ever-growing population).

  2. Life is way to complicated to be summed up in a few multiplications, but it was fun to try anyway…

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