Population Bottleneck


I wrote before about the difference between the mathematical meaning of “proof” and the “proof” needed to accept a scientific theory. They are different. To expect mathematical “proof” of any theory is neither possible nor how science works. It’s not an analogy–it’s a difference in the definition of the word. By your definition, there is no proof of ANY scientific theory at all. And thus no science.

Plus I’ll add once again that Ratzinger was giving a speech. He has no scientific training. His opinion on this matter, in this setting, is the same as any person who doesn’t have specialized education in the subject. In other words, your opinion or my opinion.

I’m not trying to “promote” anything. Those who wish to live in ignorance are perfectly free to continue doing so. There are a lot of people who believe in aliens, that the earth is flat, and that Scientology is 100% correct. I’m just not one of them.


You are, knowingly or unknowingly, promoting something.

Look up the the term “engineering consent.”


FYI - Jerry Coyne hesitates to call it a new species.


The new marbled crayfish gained in function? I am not so sure of that yet. But before I put my 2 cents, please consider this scenario:

Assume that we have a population of organisms that have one eye, which later evolved into a population of organisms with two eyes. Was there a gain in function? One person might say yes, because it now has a wider vision since it now has two eyes. However, I can say no, because the new eye that developed has the same function as the single eye, which is the function of vision. The new two-eyed organism gained an advantage , but it did not gain a new function.

Now, suppose a population of one-eyed organisms evolved out of a population of two-eyed organisms. Did it lose a function? According to my understanding, the answer is also no, because it still has the ability to see. It merely lost the advantage of being able to see more, but it didn’t lose the function of seeing.

I think that it is the same situation that I find with the evolution of the marbled crayfish. The new marbled crayfish did not gain a new function (which is the ability to reproduce), but it lost the advantages that go with sexual reproduction.

So, I guess it depends on how you define "gain in function.”


Would not stereoscopic vision be a gain in function? Depth perception?


The problem with one eye is seeing things within 15 feet or so becomes problematic. Having two eyes set at a precise distance apart increases field of view and depth perception, which is the way humans experience it. However, birds have a single eye on both sides of the head but the eyes sometimes can see for greater distances compared to humans, and hawks can navigate tight spaces at high speeds, requiring precision eye, wing and body coordination.


Two eyes gives depth perception, which one eye does not.

ETA: Reminder to self, read StephieNorthCo’s post first before posting. :frowning:



Depth perception is not a function of the eye per se. Because the eye itself does not “see” depth. Depth perception is more an interpretation made by the brain based on visual cues provided by the eye, or by two eyes, if the organism has two eyes. In fact, even organisms that have only one eye can distinguish near and distant objects from visual cues provided by one eye. For example, distant objects appear smaller, while closer objects appear bigger. In either case depth or distance perception seems to be more a function of the brain than of the eye itself.

Having two eyes is definitely an advantage, but not a new function. Having two eyes does not add a new function to the brain either. Two eyes only add more visual cues and data to the brain, but it is still the brain that makes the interpretation of distance or depth.


See my response to StephieNorthCo.


This would be adaptive fine tuning.


What does depth perception have to do with a population bottleneck?


Is there a Catholic reason stopping you?


For the record, does anyone here believe that the earth is flat?


No, the earth is not flat, I do not believe in aliens and have studied Scientology and have found nothing worthwhile there. References like this are meant to add meaningless noise to the discussion and a “guilt by association” effect. The poster knows better.


That can be easily disproved.


Yes it can but somebody, somewhere (probably somebody reading this), does believe it.


No. Not at all.


You’re not keeping up with your NBA basketball trivia:

And hey! They just had their annual convention!


LOL! I think somebody years ago on CAF was a flat earther.


And this has what to do with the topic?

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