It still isn’t random

This is apparently some confusion over my post about why natural selection is not random. It’s a fairly elementary issue at hand, but it evidently needs to be addressed. One reader mentions,

Natural selection is a product of selective pressures. Those selective pressures are random in that they do not try to produce anything specific (ie: original appendages, limbs, organs, organ systems, body plans, etc… or the DNA that codes for them).

This user is right so far, even if the language is a bit dicey. A particular environment produces conditions to which a population then responds. A research job from a biology professor of mine will do fine here: there are two species of fish in a stream, one small, one large. This stream is divided into two sections: an upper area and a lower area. The division is due to a small waterfall. Now, the small fish in the top section of the stream tend to be vibrant in color while the lower small fish are a more gray color. The hypothesis is that the large species of fish is unable to traverse the waterfall so thus unable to eat the upper small fish, hence their vibrancy. So the research team takes some large fish and introduces them into the area with the vibrant fish. Sure enough, the fish lose their vibrancy pretty quickly. Conclusion: The hypothesis was not falsified because a correlation between color vibrancy and survival was shown upon introduction of the large fish species to the upper stream.

So now here’s where the user goes awry.

Hence, natural selection is random.

He concludes that because the selective pressures happen without regard to a particular species that the reaction of the species is thus random. Do you see the inane logic? This is like saying that because what particular rocks, gas, and space junk goes into the making of a planet can be called random that the force behind the accretion process – gravity – is random.

It’s all very simple. Natural selection is the process of differential survival of organisms based upon how they respond to a given environment. That means that natural selection happens with regard to adaptability. And maybe this is the kicker for this silly creationist. That’s really all “non random” means – with regard to adaptability. That’s why any aspect of genetic drift or mutation is considered random. It happens regardless of whether an organism will do better, worse, or the same in its survival. Were natural selection random then we should expect to see a number of vibrant fish swimming around the upper stream which is in comparable proportion to the number swimming around prior to the introduction of the large fish species. Of course we do not see anything like that. What we do see is differential survival based upon the response of the organism to a particular environment – the fish which survived were less vibrant, on average, than the fish which were quickly eaten.

It still isn't random

This is apparently some confusion over my post about why natural selection is not random. It’s a fairly elementary issue at hand, but it evidently needs to be addressed. One reader mentions,

Natural selection is a product of selective pressures. Those selective pressures are random in that they do not try to produce anything specific (ie: original appendages, limbs, organs, organ systems, body plans, etc… or the DNA that codes for them).

This user is right so far, even if the language is a bit dicey. A particular environment produces conditions to which a population then responds. A research job from a biology professor of mine will do fine here: there are two species of fish in a stream, one small, one large. This stream is divided into two sections: an upper area and a lower area. The division is due to a small waterfall. Now, the small fish in the top section of the stream tend to be vibrant in color while the lower small fish are a more gray color. The hypothesis is that the large species of fish is unable to traverse the waterfall so thus unable to eat the upper small fish, hence their vibrancy. So the research team takes some large fish and introduces them into the area with the vibrant fish. Sure enough, the fish lose their vibrancy pretty quickly. Conclusion: The hypothesis was not falsified because a correlation between color vibrancy and survival was shown upon introduction of the large fish species to the upper stream.

So now here’s where the user goes awry.

Hence, natural selection is random.

He concludes that because the selective pressures happen without regard to a particular species that the reaction of the species is thus random. Do you see the inane logic? This is like saying that because what particular rocks, gas, and space junk goes into the making of a planet can be called random that the force behind the accretion process – gravity – is random.

It’s all very simple. Natural selection is the process of differential survival of organisms based upon how they respond to a given environment. That means that natural selection happens with regard to adaptability. And maybe this is the kicker for this silly creationists. That’s really all “non random” means – with regard to adaptability. That’s why any aspect of genetic drift or mutation is considered random. It happens regardless of whether an organism will do better, worse, or the same in its survival. Were natural selection random then we should expect to see a number of vibrant fish swimming around the upper stream which is in comparable proportion to the number swimming around prior to the introduction of the large fish species. Of course we do not see anything like that. What we do see is differential survival based upon the response of the organism to a particular environment – the fish which survived were less vibrant, on average, than the fish which were quickly eaten.

Eyespots

History recently aired a series called “Evolve” which focused upon various aspects of evolution: wings, sex, guts, etc. But the most interesting episode was probably the one on eyes. It’s pretty clear they started out with eyes because of all the hub-bub made by creationists who find this organ to be too complex to have evolved by blind chance (what about the brain?). Natural selection is not chance (though it is blind – half credit), but such a misconception is one of the reasons eyes needed to be a starting point.

What History didn’t do, however, was get down to the cellular level of eye evolution. They may have touched upon photoreceptive cells, and that’s technically the cellular level, I suppose, but it overlooks an important aspect of evolution: everything which evolved today began its evolution (eventually) at the cellular level. So it is to my delight that I came across a Wikipedia article on eyespots.

Eyespot apparatus of euglena

Eyespots are a lot like they sound they are. They’re photoreceptive areas found in some plants cells (algae) and even in single celled organisms such as the euglena featured above. These are simply areas which cause a reaction to light – it becomes too bright, you may be too close to the surface. Swim away.

The advantage should be quite clear. The ability to detect light – not shape, size, dimension, or detail – gives an organism a lot of information about its environment. Specifically, History did address the eyespots of certain squids. These squids, only having nervous systems (no brains), would simply go into a sort of lull when coming near a certain wave length of light. As it not-so-coincidentally happens, that wave length corresponds with the wave length common near the food source of these squids.

Here’s the interesting kicker for which I think everyone should perk up: the origin of these eyespots works upon signal transduction, which is initiated by enzymes. This is what happens in every cell everywhere. Enzymes catalyze various things within cells. Lactase, for example, catalyzes lactose into galactose and glucose monomers – you drink milk, proteins (lactase) in your body will break it down into its constituents. It’s basic biology.

So how do new enzymes arise that can cause the formation of eyespots? This is a matter of a mutation within the DNA of a cell. Some “letter” of DNA is changed through some sort of error in copying. It happens all the time. You have 50-100 mutations in you right now (most, if not all, are probably neutral). DNA replication isn’t perfect. So a simply mutation can quite easily code for a new enzyme, which can cause the formation of an eyespot – the beginning of the eye. A slow, cumulative building through, perhaps, further mutation combined with the non-random action of natural selection can (and has separately over 40 times) evolve a complex eye worthy of fighting on the evolutionary stage of life.

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