A: What is “evolution”?
B: Evolution is descent with modification.
A: Oh? As simple as that? So……can we go home now?
B: Slow down – sometimes simple explanations are the hardest to understand – so let me unpack this one a bit.
Evolution is the ubiquitous process through which all that was came to be all that is, and through which all that is will become all that will be. That might seem cryptic or hand-wavy, but it’s just a simple statement. Evolution is prosaic.
Evolution is not “natural selection”. Natural selection is not a “type” of evolution. Natural selection is a particular kind of constraint that shapes the consequences of evolution in biological systems. It is not the only kind of constraint that shapes biological evolution, but it’s an important one. Natural selection is one of the best ideas ever produced by hairless apes, because it explains why some of the results of evolution look the way they do (to us).
Evolution is just descent with modification. The future states of a system depend upon (are descended from) prior states. Systems (ones that are actual) are not static – future states are different from prior states. That is evolution: breathtakingly simple and utterly universal.
There are those that wish to defend the word “evolution” from this interpretation, as though it might be tarnished by it. “Following this argument,” they (might) say, “the weathering of a rock, its transformation from a boulder into sand, would be considered its ‘evolution’.” Indeed. As would the transformation of the sand back into rock, were that the sand’s fate. I repeat: evolution is prosaic.
“Change is the only constant.” A truism that happens to be true. Aristotle thought that the default state for all things was for them to be at rest. He thought energy had to enter a system in order for movement to be initiated. He used this logic to construct his “prime mover”, or “unmoved mover”, argument. Aristotle was wrong. Heraclitus (a precursor of Aristotle) was closer when he said “everything is in flux and nothing is at rest”. Modern physics refutes Aristotle’s argument – at the “bottom” all is change, all is movement. In fact, Aristotle had it precisely backwards – “energy” is required to prevent change, not to cause it, and even then it’s just a temporary preservation of some “pattern” or another. “All patterns are ephemeral!”, cries the evolutionist.
A: A bit morbid, these evolutionists…
B: Death and taxes, my friend.
Anyway, change is constant, but not all change is permissible, because future states descend from prior states. Future states are constrained by prior states. Evolution, as manifest in the actual universe, is a process that takes place across time. Yes my dear, time is real! The past constrains the future and the deepest level at which we can observe this is by considering the laws of physics themselves. Since evolution is a process in time, if evolution is ubiquitous time must be fundamental and the laws of physics therefore cannot be “outside time”. Lee Smolin hits the nail on the noggin: the laws of physics evolved. Once evolved, they constrained all future evolution. They are one of the earliest “selection pressures”.
A: Why don’t the laws of physics keep evolving then?
B: Huh? I dunno….maybe they do, but maybe they are heavily constrained by something else. I didn’t claim to know everything…..and I was on a roll, do you have to keep interrupting?
B: That’s OK, it was a good question. Anyway, let me sum this up so we can get on with our lives.
Evolution is like this: change is constant, but every system has a set of degrees of freedom which constrain its possible future states. These are the selection pressures or “principles of selection”, or whatever semantically isomorphic phrase one wishes to coin. Different systems….
A: Semantically what?
B: “Semantically isomorphic” – it just means a different choice of words with the same meaning.
A: Well why didn’t you just say that?
B: I think my facial expression says it all right now. Aaaaaanyway:
Different systems have different principles of selection (and working these out is the hard, explanatory task of the evolutionary sciences). Selection pressures themselves evolve, of course, and the laws of physics are an example. The biological sciences have identified thousands of examples, some of which constitute “natural selection”. Systems of ethics are another example – they evolved and they constrain future evolution.
A: Sorry what? I was just checking my Instagram feed…
B: Ah. Fair enough I guess. Have you ever read any Marx?
A: Huh? I thought we were done with all this intellectualising once you got through the evolution schtick?
B: We are, but this is funny – one of Marx’s most famous slogans was “permanent revolution!”; little did he know that reality was in a state of permanent evolution!
A: That’s not funny.