Natural selection in humans.

[Eckhart Aurelius Hughes]

There is no way to 'defeat' the process of natural selection. Remember fitness, in the sense of natural selection, is relative to the environment. So if a group of people tends to survive less after some sort of change in their environment, then they are less fit in that environment then they were in the previous environment. A quality that may make a creature more fit in one environment (e.g. being physically strong, being monogamous, being able to breathe air) may make a creature less fit in another environment.

If a species of monster suddenly came to the planet that only eats people who don't have blue eyes, that would be a change in the environment. In the new environment that includes the monster, having blue eyes would make one more fit while not having blue eyes would make one much more unfit. Natural selection may be said to occur if in that new environment the population of blue eyed people increased and the population of non-blue eyed people decreased.

It is also important to note that overpopulation is a main contributing factor to evolution. Overpopulation creates competition for survival which amplifies natural selection and is a catalyst for leaps in evolution. This is why evolving does not happen steadily, but seems to occur in leaps. So it's very incorrect to an ironic degree to suggest that overpopulation is some sort of antithesis to natural selection.

[ChrisLawrence]

From Scott (Post #16):

It is also important to note that overpopulation is a main contributing factor to evolution. Overpopulation creates competition for survival which amplifies natural selection and is a catalyst for leaps in evolution. This is why evolving does not happen steadily, but seems to occur in leaps. So it's very incorrect to an ironic degree to suggest that overpopulation is some sort of antithesis to natural selection.

Indeed. But I think the irony in the human context is that over-population, at least in much of the world, does not drive natural selection in the way it does with non-human populations. Because ‘natural’ natural selection has been weakened by eg public health & technological improvements in food production, over-production of individuals does not result in survival of the fittest, but of survival of (almost) all.

Of course in much of the world too the over-population is limited by contraception & ‘family planning’ in general. This is also counter to ‘natural’ natural selection, which works more by culling!

[Eckhart Aurelius Hughes]

If everyone is surviving then there is not overpopulation in a biological sense. This is not unique to humans. There are times when members of a species do not have to compete much to survive, and thus the population often tends to increase until they become overpopulated at which point natural selection occurs which leads to evolution. The fact that the human population is increasing is evidence that we are not overpopulated in a biological sense.

[ChrisLawrence]

From Scott (Post #18 ):

If everyone is surviving then there is not overpopulation in a biological sense. ...The fact that the human population is increasing is evidence that we are not overpopulated in a biological sense.

Yes I would agree with that. In fact ‘If everyone is surviving then there is not overpopulation in a biological sense’ could well be true by definition. There is however a less biological sense of ‘overpopulated’ which is relative to some constraint like services or resources. We might say a city or shanty town is over-populated when its infrastructure cannot support it, and ‘emergency’ measures need to be taken. But you are right, that is not overpopulation in the biological sense.

In those regions of the world where population growth is constrained by pre-reproductive (eg infantile) mortality, there is certainly ‘selection’, but whether it counts as ‘natural’ depends on one’s definition of ‘natural selection’. If by definition it is selection of genetically inheritable variation, then I doubt whether much pre-reproductive mortality counts as natural selection.

I think the reason why the inheritance of sickle-cell anaemia still counts as natural selection in humans is this. It may be that the treatment of sickle-cell anaemia itself is more effective than that of cerebral malaria. The treatment itself would be ‘artificial’ rather than ‘natural’. But the effect might be that the relative sickle-cell gene frequency grows, because of pre-reproductive deaths from cerebral malaria. If the treatment of cerebral malaria was more effective than that of sickle-cell anaemia, then the relative sickle-cell gene frequency would fall.

Another more general example would be the inheritance of resistance to incurable (or not completely curable) viral or bacterial infections which could be fatal, particularly at pre-reproductive ages.

[Belinda]

ChrisLawrence explains the received understanding. There is some new evidence that learned characteristics can jump across the boundary between the genetic cells and the other cells in a sort of Lamarckian way.I cannot cite the article I read but will try to find something. If it is weighty at all it should be in 'Nature'.
http://www.technologyreview.com/biomedicine/22061/?a=f

[ChrisLawrence]

This is in response to Meleagar (Post #14).

You question my acceptance that natural selection of inheritable variations is an explanation of evolution in principle, and challenge me to provide

...a mathematical analysis of the capacity of natural selection to sort ... [and] an analysis of how often one can expect a sortable variation to be produced by genetic variation ... [and] a paper that describes the algorithmic capacity of natural selection to act on such features and how this sorting process can beat a random distribution.

I cannot. The mathematics is beyond me. I would however really welcome a summary of (&/or pointer towards) what the ‘sorting’ problem is. (As a start.)

I would also be very interested to hear people’s views on some of the implications if a variant of ‘intelligent design’ did turn out to be true.

One is the existence of evident design flaws in nature – which seem more explicable on a basis of incremental adaptation rather than purposeful, teleological design.

Another, which could be a special case of a design flaw, is the possible argument that if there was an intelligent designer which deliberately initiated life, then that intelligent designer seems at best callous and at worst deliberately cruel. This is in consideration of the evidence of over-production of offspring and the fact that many foodchains involve the agonising death of sentient creatures.

These are not arguments against intelligent design, more an inquiry into what that intelligent designer might be (or have been) like.

[Meleagar]

I cannot. The mathematics is beyond me. I would however really welcome a summary of (&/or pointer towards) what the ‘sorting’ problem is. (As a start.)

Current evolutionary theory states that a material variation processes (genetic mutations) and a sorting process of choosing variations (natural selection) which are not teleologically intended to reach the engineering/software result in question (functioning flight, stereoscopic eyesight, etc.) can in fact successfully build such a functioning mechanism.

That's an amazing claim in my book, considering the level of sophistication of theinterconnected, nested heirarchy of coded programming language and corresponding engineered systems we find in living organisms; it is exactly like expecting that one could build a functioning, computerized, self-replicating, self-operating battleship without a blueprint, without any knowledge of the engineering principles and requiremetns involved, and without any understanding of software programming whatsoever. IOW, it's like building that computerized, self-sustaining, self-replicating battleship from scratch by chance (and by "chance" meaning without even the idea of your final goal).

If one is going to claim that their methods of material generation, construction, sorting and testing is up to that kind of task, then one needs to be able to show that it is. Otherwise, one can only consider such a claim at best a hypothesis.

One is the existence of evident design flaws in nature – which seem more explicable on a basis of incremental adaptation rather than purposeful, teleological design.

Bad or imperfect design, even if it exists, is not an argument against intelligent design; it's a theological argument against a particular kind of designer. Intelligent designers like humans generate non-optimal designs all the time.

Another, which could be a special case of a design flaw, is the possible argument that if there was an intelligent designer which deliberately initiated life, then that intelligent designer seems at best callous and at worst deliberately cruel. This is in consideration of the evidence of over-production of offspring and the fact that many foodchains involve the agonising death of sentient creatures.

Again, this is a theological argument, not an argument agaisnt I.D. The scientific theory of ID doesn't make any claims about the nature of the designer other than that it is intelligent (IOW, it matches means to an end, whether or not the means and/or the end are optimal or "good".

These are not arguments against intelligent design, more an inquiry into what that intelligent designer might be (or have been) like.

You're right, they're not, and this thread isn't about ID, it's about natural selection in humans, so a discussion about ID would be off-topic.

As far as I'm concerned, natural selection has never been shown to be a major contributor in evolution, or to be capable in principle of doing much at all. So, IMO, there's nothing for humans to defeat. As far as "are humans still evolving", I think all organic entities evolve. I don't think, however, that how they evolve has ever had that much to do with "random" mutation and natural selection.

[ChrisLawrence]

ChrisLawrence explains the received understanding. There is some new evidence that learned characteristics can jump across the boundary between the genetic cells and the other cells in a sort of Lamarckian way.

Thanks for the link (see Post #20). I remember hearing of this before. Assuming this is substantiated as an actual evolutionary mechanism wouldn't it complement natural selection of chance variation rather than challenge it?

[Belinda]

ChrisLawrence, yes I think that the new sort of Lamarckian process would complement rather than replace natural selection. The article that I read pointed out that the discovery of the Lamarckian thingy makes evolution a lot more complex than simple natural selection would have it.


Meleagar wrote

That's an amazing claim in my book, considering the level of sophistication of theinterconnected, nested heirarchy of coded programming language and corresponding engineered systems we find in living organisms; it is exactly like expecting that one could build a functioning, computerized, self-replicating, self-operating battleship without a blueprint, without any knowledge of the engineering principles and requiremetns involved, and without any understanding of software programming whatsoever. IOW, it's like building that computerized, self-sustaining, self-replicating battleship from scratch by chance (and by "chance" meaning without even the idea of your final goal).

This is as you will recognise, Meleagar, an analogy. Another analogy which I suggest is more appropos is that of me baking a Victoria sandwich cake. I don't add the eggs until the butter and sugar are what I consider to be adequately creamed. I don't add the flour until the butter sugar and egg mixture is just right. I dont mix in the flour to what I consider to be too enthusiastically mixed. I don't add too much milk, just enough for a soft dropping consistency.If you substitute for 'I' what a computer programme says about the logical sequence 'if---then' with regard to baking a Victoria sandwich cake you will get just as good a cake as I can make.


If I make a mistake and the cake mixture is for all my efforts a failure I may still use it in some other way, for an apple pudding, for the bird table, for fruit cup- cakes, for making a joke about. Whatever. The computer could no doubt be programmed to apply if--then alternatives too.

Natural selection is like this, a recipe, not a blueprint.The blueprint is a fixed goal with fixed methods: the recipe can be adapted as to product and method. Nature has no fixed goal as in a blueprint, but life is such that it adapts to change.Natural selection is one of the adaptation equations.

[Meleagar]

Another analogy which I suggest is more appropos is that of me baking a Victoria sandwich cake. I don't add the eggs until the butter and sugar are what I consider to be adequately creamed. I don't add the flour until the butter sugar and egg mixture is just right. I dont mix in the flour to what I consider to be too enthusiastically mixed. I don't add too much milk, just enough for a soft dropping consistency.If you substitute for 'I' what a computer programme says about the logical sequence 'if---then' with regard to baking a Victoria sandwich cake you will get just as good a cake as I can make.


If I make a mistake and the cake mixture is for all my efforts a failure I may still use it in some other way, for an apple pudding, for the bird table, for fruit cup- cakes, for making a joke about. Whatever. The computer could no doubt be programmed to apply if--then alternatives too.

Natural selection is like this, a recipe, not a blueprint.The blueprint is a fixed goal with fixed methods: the recipe can be adapted as to product and method. Nature has no fixed goal as in a blueprint, but life is such that it adapts to change.Natural selection is one of the adaptation equations.

A recipe is a blueprint in the sense that a recipe is a fixed goal. Baking a cake requires the same teleology towards the specific goal as a blueprint. Even the alternative end result of pudding if one fails to bake the cake is a teleological goal that requires information about that outcome to reach.

Now, if your materials and baking equipment spontaneously bake a cake or make pudding without any teleological recipes whatsoever, then you'd have a counter-analogy. But you do not, nor do you even have a statistical table that demonstrates that there are enough probabilistic resources in the universe to get either a cake or pudding or any other edible, tasty results via spontaneous generation.

Claiming that such recipes can self-generate is not demonstrating it via a probabilistic analysis of the materials and forces involved.

[Unrealist42]

I see no aliens leaning over the planet and selecting who gets to mate and who does not. If that was so there could be some argument over whether or not natural selection has been mooted.