Q. How do you define life?
A. The most stable response to the environment when life began.
Q. What is adjusting?
A. Carbon compounds in a liquid water environment
Q. What do they adjust to?
A. The day/hot – night/cool cycle, and perhaps dry – then wet cycle too. Plus they adjust to UV light from the sun.
Q. How do they adjust?
A. What lasts in that environment is the most stable. With some carbon compounds more stable than others.
In this case stable means two things: stable in what keeps it as it is, and stable in the ability to adjust in ways that improve it’s stability. Both metabolism and reproduction are ways to make life more stable.
Q. LIfe seems fragile not stable.
A. When we compare it to it’s environment: earth, sea, and atmosphere, we find that life has outlasted all 3 (excluding some zircon seeds). The earth has changed through plate tectonics, the atmosphere is no longer reducing, and the seas have been sterilized by undersea vents. Collective life is more stable and has outlasted all 3.
So life is what is most stable in that early environment, with the ability to adjust to become better adapted to that environment or changes in that environment over time.
Q. How does it adjust specifically?
A. Through natural selection of better anabolic ( build up) or catabolic (break down) processes.
Q. So every change in living things is toward a better anabolic or catabolic response to the environment?
A. Yes. This suggests there is a direction in natural selection – always toward better anabolic and catabolic processes.
Q. Why two directions?
A. Anabolic and catabolic adjust or evolve, but they adjust separately and do not blend. There has never been found a time and place where anabolic processes are building up at the same time that catabolic processes are breaking down.
Q. Do these two directions influence each other?
A. They may. Positive change in an anabolic process, may put selection pressure on catabolic processes to catch up (or vice versa). Negative change in an anabolic process, may be mitigated by the stability of the catabolic processes in place (or vice versa.)
Q. How does the information in DNA fit into this?
A. The information being transferred is for more stability in the way outlined above.