Evolution may not act as an optimizer globally, since selective pressure is different for different populations of organisms on different niches. However, it does act as an optimizer locally.
For a given population in a given environment that happens to be changing slowly enough, the set of all variations in each generation act as a sort of numerical gradient estimate of the local fitness landscape. This allows the population as a whole to perform stochastic gradient descent. Those with greater fitness for the environment could be said to be lower on the local fitness landscape, so their is an ordering for that population.
In a sufficiently constant environment, evolution very much does act as an optimization process. Sure, the fitness landscape can change, even by organisms undergoing evolution (e.g. the Great Oxygenation Event of yester-eon, or the Anthropogenic Mass Extinction of today), which can lead to cycling. But many organisms do find very stable local minima of the fitness landscape for their species, like the coelacanth, horseshoe crab, cockroach, and many other “living fossils”. Humans are certainly nowhere near our global optimum, especially with the rapid changes to the fitness function wrought by civilization, but that doesn’t mean that there isn’t a gradient that we’re following.
Also, consider a more traditional optimization process, such as a neural network undergoing gradient descent. If, in the process of training, you kept changing the training dataset, shifting the distribution, you would in effect be changing the optimization target.
Each minibatch generates a different gradient estimate, and a poorly randomized ordering of the data could even lead to training in circles.
Changing environments are like changing the training set for evolution. Differential reproductive success (mean squared error) is the fixed cost function, but the gradient that the population (network backpropagation) computes at any generation (training step) depends on the particular set of environmental factors (training data in the minibatch).
This is somewhat along the lines of the point I was trying to make with the Lazy River analogy.
I think the crux is that I’m arguing that because the “target” that evolution appears to be evolving towards is dependent on the state and differs as the state changes, it doesn’t seem right to refer to it as “internally represented”.
Evolution may not act as an optimizer globally, since selective pressure is different for different populations of organisms on different niches. However, it does act as an optimizer locally.
For a given population in a given environment that happens to be changing slowly enough, the set of all variations in each generation act as a sort of numerical gradient estimate of the local fitness landscape. This allows the population as a whole to perform stochastic gradient descent. Those with greater fitness for the environment could be said to be lower on the local fitness landscape, so their is an ordering for that population.
In a sufficiently constant environment, evolution very much does act as an optimization process. Sure, the fitness landscape can change, even by organisms undergoing evolution (e.g. the Great Oxygenation Event of yester-eon, or the Anthropogenic Mass Extinction of today), which can lead to cycling. But many organisms do find very stable local minima of the fitness landscape for their species, like the coelacanth, horseshoe crab, cockroach, and many other “living fossils”. Humans are certainly nowhere near our global optimum, especially with the rapid changes to the fitness function wrought by civilization, but that doesn’t mean that there isn’t a gradient that we’re following.
Also, consider a more traditional optimization process, such as a neural network undergoing gradient descent. If, in the process of training, you kept changing the training dataset, shifting the distribution, you would in effect be changing the optimization target.
Each minibatch generates a different gradient estimate, and a poorly randomized ordering of the data could even lead to training in circles.
Changing environments are like changing the training set for evolution. Differential reproductive success (mean squared error) is the fixed cost function, but the gradient that the population (network backpropagation) computes at any generation (training step) depends on the particular set of environmental factors (training data in the minibatch).
This is somewhat along the lines of the point I was trying to make with the Lazy River analogy.
I think the crux is that I’m arguing that because the “target” that evolution appears to be evolving towards is dependent on the state and differs as the state changes, it doesn’t seem right to refer to it as “internally represented”.