Wednesday, December 16, 2009

Life is an entropy exchange

Just one more word about this evolution thing.
Naysayers often point to the Second Law of Thermodynamics to support their view that evolution can't be true because entropy (chaos, disorder, randomness...) increases.

quick review of the laws:
0 = definition of temperature
1 = conservation of energy
2 = entropy of an isolated macroscopic system never decreases
3 = as temperature goes to absolute zero, entropy approaches a constant minimum

The laws do not at all forbid evolution of complex organisms. They just tell us this added complexity has to be paid for.

OK. A complex organism has less entropy than a simple one. So it's going against the grain to go from simple to complex, and in the case of the magnificent human brain it's just unreasonable.
But hey, we appear to go against the Second Law all the time. Meerly by growing, the simplest bug decreases its own personal entropy.
How can that be?
Well, you have to consider the "isolated macroscopic system". An individual is not an isolated system. It eats. It breathes. It metabolizes. It shits. It has an impact on its environment. To draw a circle around the 'system' here, you have to include the entire planet, plus the moon because its pull provides us with the energy that moves the oceans around, plus the sun because of the energy it send us.
And now there's plenty of room to mess with the conservation of energy and increasing entropy. Living organisms are constantly involved in converting one form of energy to another, and in increasing entropy here to decrease it there. Many developments in body form cost energy (it takes an effort to make an eye, it takes energy to make thick bark), but if that development is more advantageous than costly (finding food more easily, resisting beetles) it will be retained. A development no longer advantageous (like dewclaws) will fade away as its parts degenerate or are co-opted for new uses.
We humans cannot always think of what advantage is being gained, so we cannot explain everything. Sometimes the advantage no longer is one. It can take a long time to adapt to a given circumstance, and when that circumstance changes, the old adaptation may persist for many generations.
The Laws of Thermodynamics have nothing to say against evolution. They just tell us to look at the whole system, and that local differences in entropy even out in the system as a whole.


Bagman and Butler said...

Uh...I think I know why my high school desire to be a scientist turned into a college desire to be a writer. Number 1: Science baffled me because I had too much entropy...or too little. Not sure now. Number 2: Writing provided more opportunities to drink and smoke pot.

Ann said...


This is a real cat cafe. When are you cats getting served?

Argent said...

Telling it like it is! Love the new banner.

Ronda Laveen said...

I like the way you thing, girl. Like Bible referrences, people quote the Second Law of Thermodynamics to suit their own agendas.