yawning is supposed to cool the brain<\/a>.<\/p>\nBut that’s for another day.<\/p>\n
Anyway, I know this is a departure from what I usually post here, but this is my blog, so I can post huge, rambling stuff like this if I want. I’m defensive about it, aren’t I?<\/p>\n
Here it is, straight from my journal, circa 1998:<\/p>\n
I spoke to Chris more than the others, and we had a long conversation about (among other things) bacteria. He\u00e2\u20ac\u2122s interested in microbiology, and is thinking of specializing in environmental microbiology. He told me about his experiment at university, which was pretty interesting to me.
\nThe idea was that bacteria which are resistant to certain antibiotics (tetracycline, for instance) are using genetic energy to pass this resistance on to future generations.<\/p>\n
Chris figured that if the presence of the antibiotic was removed, then eventually the resistance should disappear. In other words, the bacteria would stop wasting energy to fight a drug that was non-existent. As they say, there\u00e2\u20ac\u2122s much to miss twixt the cup and lips; the experiment failed. Generation after generation continued to have resistance. He was disappointed, but still feels that eventually the thing would have worked.<\/p>\n
I ended up learning a bit from him, because I\u00e2\u20ac\u2122d often considered the idea of an animal losing an obsolete adaptation, and find it hard to understand. That is, it\u00e2\u20ac\u2122s easy to see how a mutation which increases fitness will soon become the norm, but it\u00e2\u20ac\u2122s harder to see how the animal exhibiting the loss of an earlier adaptation will automatically make headway against those animals retaining it. Consider the smallest toe, for example, or maybe the appendix.<\/p>\n
Why would some mutant born without one of those things have any advantage over the rest of the population? I can see that they\u00e2\u20ac\u2122d have no disadvantage, but that\u00e2\u20ac\u2122s not exactly the same thing, is it?<\/p>\n
Well, he didn\u00e2\u20ac\u2122t really shed any light on that for me, so I shouldn\u00e2\u20ac\u2122t have started the last paragraph by saying that he taught me anything. He did, but that\u00e2\u20ac\u2122s coming up later. As far as this topic goes, the only guess I have is that the body that doesn\u00e2\u20ac\u2122t waste energy making obsolete stuff, can maybe put that energy to good use somewhere else. Maybe by making an existing adaptation better, or even by fueling a new adaptation.<\/p>\n
Then, you\u00e2\u20ac\u2122d have to have a lot of mutants because it\u00e2\u20ac\u2122s a random thing, and most of the time the energy would NOT be going to improving the fitness. So you\u00e2\u20ac\u2122d have all these freak occurrences of non-little toes, and every once in a while the extra energy would actually go to something worthwhile. Which is the same as saying that the new being would have greater fitness.
\nSo, these were the lines along which I was thinking when listening to his experiment. I said something about how the loss of an attribute must take an immensely longer time to become standard than the emergence of a new attribute.<\/p>\n
This is what he told me:<\/p>\n
Often, bacteria can change it\u00e2\u20ac\u2122s genetic make-up without resorting to mutation. If a certain element is present in the environment, that element can cause chemical reactions within the DNA of the bacteria which allow the bacteria to use that element (like a certain food, for instance). But if the element is not around, the bacteria\u00e2\u20ac\u2122s ability to use it will automatically be shut off. One entire generation of a certain kind of bacteria may be unable to use a food source, but the entire next generation may be genetically different, and able to use it. Not mutated, but altered.<\/p>\n
So he thought that maybe this was also the case with resistance to certain elements, and that given enough time, he\u00e2\u20ac\u2122d be proven right. Anyway, I thought that was pretty interesting. It also occurs to me that if the bacteria finds it worthwhile to turn off certain attributes (like the ability to break down a particular food), then it must have to give up something else when that attribute is turned on. That is, the energy used to produce the active attribute must be taken from other attributes.<\/p>\n
Conversely, if the attribute is turned off, the energy must go towards producing better or possibly more versions of existing attributes. All this leads me to wonder if maybe a way to weaken one particular attribute of a bacteria (i.e. resistance to an antibiotic) is by turning on all the other possible attributes. That is, make the bacteria use all it\u00e2\u20ac\u2122s energy on building other pieces (i.e. ability to break down certain foods). At the same time, we should remove the presence of the antibiotic.<\/p>\n
Maybe the bacteria will weaken it\u00e2\u20ac\u2122s defenses in order to strengthen it\u00e2\u20ac\u2122s ability to use a wide variety of foods (I don\u00e2\u20ac\u2122t know what other changes bacteria can make to it\u00e2\u20ac\u2122s DNA. Maybe there are a lot of different things besides digesting food. Whatever they are, turn them all on). Maybe you can trick it into thinking that the world is all food and light (or whatever it needs) and no danger. Maybe Chris wasn\u00e2\u20ac\u2122t giving the bacteria enough incentive to change rapidly. He wasn\u00e2\u20ac\u2122t giving any other obvious way to use the energy wasted on resistance. It still should drop the useless resistance Chris\u00e2\u20ac\u2122 way, but it might take a lot longer than trying it my way. Did he think of this? Am I so obviously wrong to any biologist that there\u00e2\u20ac\u2122s no point in even trying it?<\/p>\n
Getting back to the other bit about losing an obsolete organ, consider the blind fish living in caves. They evolved from fish with eyes. How was having eyes a DISadvantage to the original animals? How was the first blind mutant actually more fit than it\u00e2\u20ac\u2122s eyed (but just as blind in the zero light water) relatives? Here again, maybe something more is at play. I see two ways of looking at it, but having never to talked to anyone who knows anything about it, I can\u00e2\u20ac\u2122t say that there aren\u00e2\u20ac\u2122t other ways. Probably someone\u00e2\u20ac\u2122s figured the whole thing out already, but I\u00e2\u20ac\u2122ll give it a go.<\/p>\n
One way involves the mutant bit. Maybe the advantage was in (like I mentioned before) the energy going to other things. Maybe the new fish had stronger senses of smell, or could feel magnetic waves, or electrical disturbances, better than their ancestors. Everyone\u00e2\u20ac\u2122s heard about blind people developing the other senses to a degree not achieved by the sighted. Imagine if from the beginning the brain \u00e2\u20ac\u0153knew\u00e2\u20ac\u009d that there would be no eyes at all, and could take the extra material and energy to improve the remaining senses, or develop a new one.<\/p>\n
So much could be achieved! So maybe that what\u00e2\u20ac\u2122s happening with these fish. Of course, the brain doesn\u00e2\u20ac\u2122t \u00e2\u20ac\u0153know\u00e2\u20ac\u009d anything, and neither does evolution, but after millions of years of mutations, eventually the best model wins, right? All you need is one fish without eyes AND with some other improving adaptation. After reading Terence Deacon, I should also mention that the brain might \u00e2\u20ac\u0153know\u00e2\u20ac\u009d in one sense whether there are eyes or not. As the neurons compete for cerebral attention, there would be a lack of input from the ocular nerves.<\/p>\n
This lack might be enough to allow other senses or neural regions to encroach on space usually reserved for the eyes. So the lack of input from the eyes (or maybe even from the physical organ of the eye) may very well be the catalyst for an improvement in another function. That improvement, or strengthening, of a different function may or may not make the fish more fit, however. The new function would have to be something valuable, and there\u00e2\u20ac\u2122s no reason to assume that it automatically would.<\/p>\n
If the fish was born and raised in darkness, would it also have encroaching neurons? Would the difference be as great as if it had no eyes at all? Would the differences be in different functions? Can a fish without eyes compensate better than a fish born in darkness? I doubt that anyone has ever tested the ability of a blind animal to cope versus the ability of a sighted animal raised and tested entirely in complete blackness, but it seems possible that there would be no difference.<\/p>\n
Either way, the first blind fish to change the cave fish world might have had to not only be blind (or at least have diminished sight) but also have some other difference which is selected for in that environment.<\/p>\n
On the other hand, maybe lack of eyes was enough of a difference. Perhaps there was a parasite which only attacked eyes. Maybe (because eyes are vulnerable parts of the body) sighted fish were more likely to become injured and die. Maybe predators can smell eyes better than other parts of the body, or they prefer to eat eyes. Who knows? In any case, though, it seems possible that the evolution may have come about purely through random mutation and selection of the fittest.<\/p>\n
The second, maybe less likely, possibility, is that some genetic response to the lack of light is involved. Thinking about the bacteria makes me consider that the same is possible with higher animals. Maybe light actually stimulates something in the DNA (or blocks stimulation of something which otherwise would be stimulated), which results in the animal having eyes. Certainly radiation of other sorts have been shown to affect following generations. Sunlight itself seems to damage DNA strands, if I understand it correctly.<\/p>\n
Maybe the DNA is organized so that the lack of light contributes to the likelihood of eyeless mutants for the very reasons I mentioned earlier about energy going to other things. It\u00e2\u20ac\u2122s easy to see why this changeabilty would genetically advantageous to a creature, in the same way that it\u00e2\u20ac\u2122s advantageous to bacteria. If a stimulus isn\u00e2\u20ac\u2122t available, then it\u00e2\u20ac\u2122s a waste to constantly prepare for it.<\/p>\n
I suppose it\u00e2\u20ac\u2122s possible even, that light absolutely affects the number of generations having eyes, rather than merely increasing the chances of a mutation. Maybe lack of light causes minute changes in DNA which eventually and automatically result in eyeless generations. How many generations? Maybe it depends on how many generations had eyes to begin with? Maybe each time light hits the skin, or eyes of a new generation of seeing creature, the total is added to the DNA. Probably not, but it\u00e2\u20ac\u2122s interesting to play with..<\/p>\n
The point is that there are a lot of creatures who have lost attributes here and there, so even if we figure out something special for these fish, we may not be answering any major questions. I really have to talk to someone about this stuff, so I can just learn the answers, and not try to reinvent them myself. Same goes for the great yawing theory.<\/p>\n
I just read that some baboons with worn or broken teeth seem to yawn less when other males are around. This was apparently noted by Craig Packer in an article titled \u00e2\u20ac\u0153Male Dominance and Reproductive Activity in Papio anubis.\u00e2\u20ac\u009d It was published in 1979 in the magazine Animal Behavior. I read about it in the mediocre and unthought out book When Elephants Weep, by Jeffrey Masson and Susan McCarthy. They didn\u00e2\u20ac\u2122t seem to notice the implications about yawning, only pointing out that the animals seemed to be embarrassed about the condition of their teeth (or at least that they had awareness of how others perceive them). They didn\u00e2\u20ac\u2122t consider why they yawn in the first place.<\/p>\n
Right, so back to China. The nice place outside of the Bund is a bit of a walk….<\/p>\n","protected":false},"excerpt":{"rendered":"
Just skimming through an old journal of mine from my overseas days, and I came across a swath of my writing about biology, evolution, and more. Man, I can’t even remember when I had so much time. To have hours to talk to someone without interruption, then to have time to think about it deeply, […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[16],"tags":[],"class_list":["post-206","post","type-post","status-publish","format-standard","hentry","category-science-and-such"],"_links":{"self":[{"href":"https:\/\/weeklyrob.com\/index.php?rest_route=\/wp\/v2\/posts\/206","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/weeklyrob.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/weeklyrob.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/weeklyrob.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/weeklyrob.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=206"}],"version-history":[{"count":0,"href":"https:\/\/weeklyrob.com\/index.php?rest_route=\/wp\/v2\/posts\/206\/revisions"}],"wp:attachment":[{"href":"https:\/\/weeklyrob.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/weeklyrob.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=206"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/weeklyrob.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}