OT? Rigol clearance

There is no reason whatsoever to suppose that evolution will "converge on an optimal solution". If the current situation is bad enough that it exerts noticeable selection pressure for change, and if change is available (by genetic transfer, re-use of existing genes, or random mutation), then there may be gradual evolutional change.

The idea of evolution converging on or towards optimal solutions is a common misunderstanding - typically people think evolution has moved steadily from monkeys/rats/dinosaurs/fish (pick your favourite wrong answer) towards humans, then stopped. Evolution never moves /towards/ something, it does not /converge/, nor does it target the development of features or species. It makes lots of tiny local changes, and occasional bigger leaps, and stays in the new place if that proves a nicer place to stay.

That is a trade-off. Walking vertically means we can use our hands - it turns out that having bad backs but usable hands is more productive for the human species than having good backs and no hands was.

As an engineering project, the human eye is a D- at best. Some of its features are great - but those are mostly just to deal with the mess from the fundamental mistakes.

If it was made by a god, he must have been drunk at the time - or passed on the project to a bunch of student angels who were far too busy playing "Civilisation V" and handed it in after pulling an all-nighter.

Water is also almost unique as a solvent (at earth surface temperature and pressure) in being able to dissolve both organic and inorganic chemicals. There is not, AFAIK, anything else that can readily dissolve salt and sugar at the same time.

Perhaps he is just thinking of the "U" here? It is common to think there are just 4 nucleotides, in A-T and G-C pairs. That is the case for almost all DNA - in RNA, the T is replaced by U. But there are some organism's DNA's that have uracil instead of thymine - and it is quite believable that this was news in the 1970's.

There are some but most are a bit exotic when compared to water.

acetonitrile (methyl cyanide) CH3CN is one but it is a bit poisonous DMSO (CH3)2SO is another possibility and fairly safe

And after that various crown ethers and cryptands some of which can be designed to scavenge particular metal ions.

Offhand I don't think any of them have a solid phase that floats on their liquid phase though. That is probably a real constraint. I know some of these solvents are used in research on synthetic photosynthesis reaction centres and in cyalume cold light glow sticks.

I have a book, by a molecular biologist, who argues that many biochemical pathways could not have evolved incrementally. None of the very many intermediate steps would do anything useful.

Evidence is easier to find if you are willing to look for it.

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hmm, maybe not the most unbiased source. review Denton pursues his avowed purpose, to critique the Darwinian model of evolu tion, in a manner alternately fascinating and tiresome. He details legitima te questions, some as old as Darwin's theory, some as new as molecular biol ogy, but he also distorts or misrepresents other "problems." For example, h e falls into the classic typological trap: organisms with the same name are all the same. He has Euparkeria as the closest possible ancestor of Archae opteryx, thus displaying either ignorance or disregard for discoveries over the past two decades. He misunderstands or willfully misrepresents the nat ure of a cladogram as opposed to a phylogeny. Much of the book reads like c reationist prattle, but there are also some interesting points. For informe d readers. Walter P. Coombs, Jr., Biology Dept., Western New England Coll., Springfield, Mass.

but evolution is by no means a step by small step process, things get used for one thing and then not used... just hanging around. (like our appendix) and then get used for something else.

I think if you look at the 'path' the bones in our ear took to get there it gives some flavor of what happens.

George H.

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All true. It suffers from other problems too. What I find odd about the NHS is its inability and/or unwillingness to effectively tackle its problems. It's all the more odd when you consider how much it pays out for its screwups.

NT

That probably falls into the wretched "Sherlock Holmes Law", i.e. "How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?"

Usually such statements indicate limited imagination on the part of their proponents.

Hence I prefer "Clarke's first law" i.e. "When a distinguished but elderly scientist states that something is possible, they are almost certainly right. When they state that something is impossible, they are very probably wrong."

Most young scientists are more than willing; if they find it then they have made a good start to a career!

But ignoring satisfactory mechanisms in preference to vague ill-conceived magic mechanisms would be ignorant and stupid.

Why should you find that odd? It applies to /all/ large organisations - commercial, non-commercial, private, public, whatever. There are almost no exceptions.

I have a book that argues that we were visited by aliens and that is how we learned a lot of our technology. The author is an archaeologist and anthropologist, so it /must/ be right.

I also have book that says the earth was made in 7 days, some 6000-odd years ago. The author is a god (it says so in the book), so that /must/ be right. Another book says the universe is cyclic and renews itself every 4 billion years or so. No one has seen evidence to the contrary, therefore /that/ must be right.

Or maybe it is simply that someone can be a reasonably competent molecular biologist without really understanding evolution - or when you have some other overriding motivation, such as money or a fixed belief in something else (like a god). It could even be something as simple as not knowing everything (science does not know everything, obviously), and being overwhelmed by the gaps.

I haven't read the book in questions, but there are certainly many biological mechanisms, structures and processes where it can be hard to understand a plausible development history. (Often we can never know the /actual/ development history - but it is good to have plausible and realistic explanations.) An oft-cited example is "What use is half an eye? None - therefore the eye could not have evolved". In reality, of course, half an eye is /extremely/ useful - you just have to understand what "half an eye" means. Other examples include the evolution of the feather. There were theories about how this could have evolved even before Denton published his book using these examples - and our understanding of them is a lot further on now.

The "exotic" bit is quite important here - there is vast amounts of water hanging around the solar system, and it is reasonable to expect the same applies in other solar systems. And while there is also a plenty of organic molecules, the more complex ones are far too rare to take the place of water.

I agree that having a solid phase that floats on the liquid phase is likely to be a huge benefit in a particular liquid being the basis for life. I don't think it is /essential/, but still a big plus.

One thing to remember in this is that properties of chemicals can be noticeably different at different pressures and temperatures. Some fluids can be better solvents at very high pressure, for example, and may then be realistic alternatives for the basis of life on larger planets. My knowledge of chemistry is not nearly good enough to say if there are good candidates here.

Just so.

My half-formed third eye has saved me from injury many many times, and I'll lay bets that's true of almost everybody.

Which third eye? The one between your upper lip and your nose. To demonstrate its existence and effectiveness: - close your two (main) eyes - hold your hand a couple of inches from your skull - move your hand from left to right - as your hand moves in front of your third eye, your eye will detect the long wavelength light emitted by your hand - and that has saved me burning my mouth/lips many times

And that's how half an eye is much better than none.

Pit vipers improve directionality by having their IR sensors in pits.

I know that several species of snakes have such a "third eye" for detecting infra-red - I did not know that other animals, such as ourselves, have a limited version of it too. (I don't think the experiment you give above is going to demonstrate it - you know your hand is there. You'd need a double-blind test to be sure :-) )

By "half eye", I was thinking more of light-sensitive organs that lack focus, and similar structures found on a great variety of animals. But IR sensors are another example.

Try it and see, while reading this posting!

Being similarly suspicious, I've found that a "single-blind" test on another person allows them to detect my hand :)

Anthropomorphism rulez.

More seriously, it is a quick demonstration that "half an eye *is* better than none" that can be given to any ignoramus that you might meet.

Do it again in pitch darkness. Eye-lids are not completely opaque.

I have tried it, and I /think/ I can detect something - but not much. I don't think the moustache helps - and my normal two eyes can't see much either without help from glasses. However, even just a slight detection is enough to demonstrate the effect. I will try to corner some ignoramuses around the office and test it out :-)

I hadn't thought about the effect of 'taches, but I do notice how cold it is without any thatch on my pate.

I haven't considered the effects of warmer hands and colder faces (nor vice versa). My palm temperature is ~31C, so presumably if the ambient temperature is close to that then little effect would be observed. Contrariwise, if it is tried with a ceramic/metal plate at say 45C, the effect should be more pronounced.

Even a slight effect should be sufficient to reduce the change of burns, and that's all that is required from an evolutionary PoV.

Indeed, and I keep shadows off the eyes.

Have you actually tried it? Optionally with an object that is hotter than a hand, e.g. a cup at 50C?

Which is exactly the reason to limit the power of large entities' control over our lives.

No need to use anything hotter. I can feel the heat of my hand. But the variation in the light that gets through my eyelids is a much stronger sensation, even in only moderate and indirect room lighting.

Why are you surprised that you can feel the radiant warmth? It's entirely what I expected. It doesn't mean I can "see" infrared in any sane interpretation of "seeing".

Clifford Heath.