Descent of testicles.

Firstly, I strongly recommend that everyone who wants to discuss the this point reads the blog post referenced by the OP - carefullyHere it is again:

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The problem cannot be solved by "cooling sperma" explanation, because:

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Here is the first error. It is not a "cooling sperm" explanation - it is about cooling the testicles. It is a known fact that in some mammalian species raising the temperature of the testicles can cause infertility. This old paper is one example and it references more. This fact lends some plausibility to the idea that cooling is the reason - certainly it is needed in those species.Neither the example of birds nor those mammals that do have undescended testicles pose a serious problem for evolution. The blog post gives sufficient information to produce a plausible outline as follows:Evolution - as an undirected process, relying on random variation does not automatically jump to the best solution. More likely it will promote the first "good enough" solution that comes along - even if it brings other problems with it. We know that the problems associated with descended testicles are not sufficient to endanger the species that have them, through the obvious fact that those species survive. It is not implausible to suggest that increased fertility (a definite evolutionary advantage) more than compensates.So, the line which the mammals are descended from adopted the solution of descended testicles in a scrotum. Some mammals have evolved other solutions - and then the descended testicles are only a disadvantage. So natural selection would favour undescended testicles in those species. This explains not only why some mammals do not have descended testicles, but the pattern found in the phyologeny, as the blog post explains.Birds come from a different line altogether - and, given the undirected nature of mutation, it is not surprising that they ended up with a different solution to the problem.

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What we observe is increasing structuring of mammalian bodies and their functions in the two poles. The head pole - responsible for individual orientation towards the world (here are almost all senses: vision, taste, hearing, smell) and the opposite pole responsible for reproduction.

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The pattern observed in the phyologeny indicates that mammals inherited the trait of descended testicles from pre-mammalian ancestors. In some species this condition has been reversed. How does this fit an "increasing structuring" ? Edited by PaulK, : No reason given.

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That discussed scrotal testicles has nothing to do with any kind of neodarwinian best or worst solution has been demonstrated by elephants. They testicles are inside their bodies near the kidneys

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It demonstrates nothing of the sort. Modern elephants have a better solution - as your yourself say. Therefore natural selection would favour that solution over descended testicles - when it arose. The evidence we have is entirely consistent with the idea that this solution arose in a species which had descended testicles.

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One should wonder what kind of force it is that has prevented other species like horses, deers, lions or apes and their ancestors to find the same solution for more than 50 million years.

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Why would there need to be a "force" preventing them ? A Darwinian view allows for a number of other possibilities. Either the necessary mutations have not arisen, or they would not constitute an immediate advantage to the ancestors of these species, or they have aquired other mutations which are in conflict with the changes needed for the elephant's solution.

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Paul, I am afraid your latest post hasn't bring nothing new for ongoing discussion.

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It refutes your assertions. If you were already aware of and understood the refutations then that, I am afraid, is your problem.

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For me it means that all "cooling spermatozoa" explanation is ad hoc neodarwinian explanation with no scientific value

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Nobody has proposed such an explanation. The "cooling testicles" explanation that has been proposed, on the other hand, has sufficient evidence to make it plausible. We know that there ARE mammalian species that can suffer loss of male fertility if the testicles are warmed to core body temperature. There is no difficulty in suggesting that this was the general condition in early mammals.You may say that this is "not new" - because I have posted it before. However the reason for repeating it is that you have not rebutted it, or even truly acknowledged it.

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I am afraid it refutes anything. Maybe for you claims like "having scrotum outside their bodies gives horses survival advantage" and "on the contrary having scrotum inside bodies gives elephants survival advantage" that this use of non-specified "survival advantage" explain something is only illusory for me.

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Except I was quite specific about the advantages involved. Avoiding the decrease in fertility caused by warming the testicles is one. Losing the disadvantages of descended testicles - which you yourself refer to - was another. I never referred to a non-specified "survival advantage".It is antics like this that get you labelled a "troll". With some justification.

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What sufficient evidence do you have on your mind?

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The evidence in the blog post, and that referred to in my initial post of course.

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Authors described their explanation as "untestable". Or using other words there is no evidence supporting it.

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You are incorrect abut the meaning of "untestable". It does not mean that there is no evidence supporting it. What it means is that there is no way to set up a decisive test that would be likely to disprove it.

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Repeating doesn't made it more plausible.

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Nor does your comment make it any less plausible. You will have to deal with my evidence if you want to do that.

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My argument is this - spermatozoa adapted to lower temperature outside body during descent of testicles. What evidence do you have that you dismiss my logic but you consider yours for the right one?

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I consider the explanation I have offered plausible, not the definite truth. You dismiss my position for no given reason - not the opposite.In fact you have offered no logic so I certainly cannot dismiss it. But in fact I have provided evidence and explanations to support my view - and you have not. The fact that some species of mammal use alternative means of cooling their testicles would also seem to be a problem for your view.

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I don't see also difficulty to see the same condition in early birds. Yet there were no descent of testicles. This argument seems to me to support my view.

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Which only shows how poorly you grasp logic. Your argument does not support your view. Given the fact that there are alternative solutions there is no reason in neo-Dawinian theory to expect birds to end up with the same solution as mammals.

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EVERY SINGLE PLACENTAL MAMMAL WITH TESTICONDY IS IN AFROTHERIA.I have checked it and it seems to be true. And according the link he has given:They (afrotheria) appear to be the most primitive of the placental mammals.--------------------------------------------------------------------------------Here is where your logic fails you. That evidence only indicates that the Afrotheria had a common ancestor with testicondy. It does not tell us whether that common ancestor appeared before or after the split between Afrotheria and the remaining placental mammals. ("Most primitive" only means that the other placentals share derived traits not found in Afrotheria, indicating that that division was the first of significance to be found in the placentals).The correct way to resolve it is to repeat the analysis with a more accurate phylogenetic tree. And I note that you miss a far more significant piece of evidence - that testicondy is also found in monotremata. That is in the phylogenetic diagram and in Knauer's comments.

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Obviously it is your custom to declare my logic as wrong. But I would reccomend you to have a look on some up to date phylogenetic tree. You would see that Monotremata, Marsupalia and Afrotheria makes a
part of tree where testicondy is most parsimonious solution. These are facts. And what's your point using strictly and correct logic?

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Of course you are confirming that I was correct to say that considering Afrotheria in isolation is not enough - the addition of monotremata is required.And even this does not get us to the point where we can say that neo-Darwinian theory is wrong or that orthogenesis is correct. Some subsidiary hypotheses have been falsified and that is all.I will take this opportunity to point out a fundamental error in your reasoning. If you want to deny that neo-Darwinian theory can plausibly account for an observation it is not a good idea to choose one where there is considerable doubt about relevant facts. The less that is known, the easier it is to construct a plausible hypothesis because known facts limit and constrain what is plausible. Words like "untestable" should be a great big warning sign in this regard because they shout out that the information that would allow us to rigourously check a hypothesis is not available.If you truly want to falsify a theory, the place to look is where the facts are most certain. That is where there is least room for the theory to escape. And even then it is difficult.