Light & Eyes

It's interesting and useful to make a distinction between linear- and non-linear responses to natural selection.

There can be a direct correlation between some environmental factor and the resulting adaptation. For example the coat-thickness of some animal will likely be a directly response to environmental temperature: when it's cold there will be selection for a thick coat and when the temperature rises there will be selection for a thinner coat. The result is a simple, linear, predictable correlation between the adaptation (coat-thickness) and environment (temperature).

There are other instances in which the relation between environment and adaptation is less linear and predictable.

Consider two time-frames:
1 There is light. There is a population of animals that don't have eyes and can't see.
2 There still is light (perhaps the same amount as in the first time-frame). Now the animals have eyes; complex constellations of functional parts, making functional wholes, that can that can perform the act of seeing.

What I'm trying to get at is that, although the evolution of seeing/eyes has of course a lot to do with the fact that there is light, the elementary fact that there is light is not a full explanation of the origin the complex system that is an eye.

More generally: a complex adaptation can evolve in response to a simple environmental factor, but that does not mean that all parts of that complex adaptation are determined by that factor.

The second, non-linear response is a, let's say, don't get me wrong, more creative response to environmental selection.
X

adaptation and adaptation

There are really two quite different ways to perceive&describe adaptation.

The first is about functional wholes and how they relate to the environment.
For example flying.

The second is about particular solutions to adaptive problems.
There is a particular constellation of bones, muscles, nerves that constitute a wing,

In both cases it is right to say that there are genes for (flying/wing structures), as well as selection of (flying/wing structures).

X

An adaptation originates at the same time as its selection pressure.

Isn't it so that an adaptation originates at the same time as the selection pressure that creates it?

Take the evolution of flight for example.

There are two steps to consider.

1 When an animal doesn't do anything resembling flying, or something that can later be called flying, there is no selection for flying. Even if it is beneficial, as well as possible, for an animal to evolve wings and take off, there is no selection for flying until it does something resembling flying.

2 When an animal starts to do something that resembles flying (dropping out of a tree in a more controlled manner for example, or jumping up and down during a mating display), there will, likely, be selection for flying. There can only be selection for flying if an animal does something resembling flying. The flying and the selection for flying originate at the same time.
X

Spore

The point about the game Spore is that, if it were true to life, it wouldn't need a player and it wouldn't be a game.
X

Whatever

I think that the "whatever" sense in natural selection is somehow deep and important...

What's being selected? (I mean positively selected)
Whatever works.

Whatever genes, creating whatever structures or behaviors, relating in whatever way to the environment, as long as these things result in an increased ability to survive & reproduce, they will be selected.

It does not depend on our ability to name, specify & understand things, for things to be selected.
X

Design comes from Nowhere (2)

So where does the shape of an eye-lens come from?

...Not from the outside: nature (as in: "natural selection")...
The particular shape if a lens, the fact that a lens "should be" translucent, these facts do not directly derive from the environment; they are not somehow specified in the outside world. (No, also not in the mind of some god.)

...Nor from the inside...
There is no, let's say, a-priory knowledge of lens-shape or -functioning inside the genome or elsewhere in the biological system that is the target of natural selection, nor an inherent tendency to produce lens-shape structures.
X

Feedback

So, in adaptive evolution, there are two types of causal links.

There is:
(1) environmental change ---------> evolutionary change

There is also:
(2) evolutionary change ---------> evolutionary change.

The elementary fact that the outcome of (2) is the same as its input, provides an element of feedback.
This feedback may well account for long term macroevolutionary trends.

(By the way, in (2) I mean evolutionary change of the population under consideration, not of the species around it, which fall under environmental change.)
X

Again... (with image)

Can this sort of environmental change lead to this sort of evolutionary change (long term trend), or not?
X

Environment & Human Evolution

The fact that adaptive evolution may well depend on the individuals changing themselves and not just on environmental change, is especially important in human evolution, because there is an extra source of change: culture.

Cultural changes changed the relation of the hominins with their environment, changing the selective regime.

This, and not environmental change, may well account for the many things that have happened in human evolution

The fact that there were many shifts in temperature&precipitation, as well as a slight trend (decline) in temperature, during the last 7 million years doesn't quite add up to an explanation of, say, the steady increase in brain-size in human evolution.
X

Change leads to Change

To make the set of (necessary) causal relations, aluded to in the last post, more explicit:

1 There is, due to selection or chance, evolutionary change.
2 This changes the properties of the organisms of a population.
3 This changes the relation of the organisms and their environment.
4 This changes the set of selection pressures acting on the population.
5 Leading to further change.
(repeat)

Ergo: there can be a whole series of evolutionary changes, macroevolution, due to selection, apart from any environmental change.
X

Environment & Macroevolution

There is a common assumption that a population changes only when the environment changes. This may well be wrong.

What constitutes a selection pressure is a consequence of both:
1 the environment
2 the properties of the organism.

This implies that there can be a series of changes in a population, theoretically without end, just because the organism changes. This is change apart from any environmental change.
X

Design comes from Nowhere

I'd like to make it clear, once and for all, that in nature, design, or rather that what we humans tend to recognize as design, really does come from nowhere.

Where does the shape of an eye-lens come from? From Nowhere.
###

Vain Search

I was rather struck by this citation from Darwin's "Origin Of Species":

In short, we shall have to treat species in the same manner as those naturalists treat genera, who admit that genera are merely artificial combinations made for convenience. This may not be a cheering prospect; but we shall at least be freed from the vain search for the undiscovered and undiscoverable essence of the term species.

The vain search is still with us.