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He baaaaack! Peter Hitchens counters, ineffectually and spleneticallyI have a student who is writing a dissertation about the evolution of opsins molecules that respond to light, which we use to see with. These molecules apparently have their origins deep in evolutionary time, long before there were animals, perhaps going back to 3.5 billion years, shortly after the appearance of life. While I was reading a draft, I wonderedwhy organisms that use electromagnetic radiation for clocks and seeing (like us) and those that use it for getting energy (like plants, algae and cyanobacteria) all use pretty much the same part of the electromagnetic spectrum the ‘visual’ spectrum. No organism can detect X rays or radio waves (which are at opposite ends of the EM spectrum). Why not?
buy canada goose jacket The Lovell radio canada goose outlet store montreal telescope at Jodrell Bank. Why are there no organisms like this? (c) Dgen buy canada goose jacket
canada goose black friday sale Unlike Jerry, I use Twitter, so I asked my tweeps why no organism can detect radio waves. Many of the answers fell into these three groups: canada goose black friday sale
uk canada goose outlet What advantage would there be? Not much radio hitting the canada goose outlet winnipeg Earth. Here’s my interpretation of what they tweeted. If they (or more likely, I) have made a mistake, chip in below. uk canada goose outlet
canada goose Organisms use electromagnetic (EM) radiation to shift molecular energy levels, either for growth (photosynthesis) or in sensation (moving protons through cell membranes). Radio is too low energy and has too long a wavelength to be able to move electrons from one energy state to another. At the other end of the spectrum, X rays would be able to do this (they can excite the inner electrons), but there are not very many of them. Visible light is both highly energetic and is mainly what the sun produces. canada goose
So the simple answer seems to be as you might expect that life has been tinkering, canada goose outlet jackets making do with what it canada goose outlet sale can find. The surface of the planet is covered with lots of this energy source, which is uniquely able to move electrons about, leading to the production of sugars in plants and sensory responses in animals (and other organisms).
canada goose clearance Later on in evolution, other aspects of canada goose outlet authentic visible light its directionality and its absorbability (?) by pigments led to the evolution of eyes, as areas of tissue shielded the detector from stimulation from all but a certain direction. If you were detecting X rays, you’d have to ingest a lot of lead to be able to detect directionality. canada goose clearance
Canada Goose online One final point struck me, about quite how energy poor radio waves are. Carl Sagan apparently said that all the radio waves detected by all the radio telescopes in the world canada goose outlet store calgary were less than the energy released by a canada goose outlet official single snowflake touching the ground. Tim O’Brien was asked on the Jodcast (a podcast produced by Jodrell Bank) whether this was true. If you listen here at around 10:00, you can hear Tim work out the answer with some simple but occasionally mind boggling canada goose outlet usa sums. Canada Goose online
Canada Goose Jackets If you don’t have the canada goose outlet kokemuksia time, the canada goose outlet las vegas summary of his answer is that the big dish of the Lovell telescope, detects 10 5 joules per year from Cygnus A, one of the brightest radio canada goose coats uk sources in the sky (800 million light years away). In comparison, a canada goose outlet boston 50 watt light bulb produces 50 joules/second) Meanwhile, his guestimate of the potential energy released by a snowflake hitting the ground is 2x 10 6 joules. This is about five times less than the energy from Cygnus A detected by Jodrell Bank in a year. So if any organism did have a reason to detect radio waves, it would have to be absolutely massive (much, much bigger than the Lovell telescope) to get any decent amount of energy out of it. Canada Goose Jackets
You can find an interesting discussion canada goose outlet online from a couple of years back of the evolution of transceivers, including references to various science fiction stories where people or animals could canada goose sale uk detect radio waves, here.
Canada Goose Coats On Sale The bottom line of this story is probably the age old evolutionary canada goose outlet in usa one of ‘if they could, they would; they don’t so they can’t’. On the other hand, at least I have a bit more of an idea of why it’s all to do with physics, man. Canada Goose Coats On Sale
canada goose factory sale h/t Tim O Tommy Ogden and a Twitter cast of thousands (OK, six). canada goose factory sale
If I remembering discussions on mammalian eyes vs avireptiles and arthropods, canada goose outlet online store mammalian eyes have extremely poor color differentiation because the basil mammalian eye was evolved official canada goose outlet for good vision in low light situations where there wasn a good range of canada goose outlet store new york color being reflected anyway.
Humans are one of only a few species of mammals that are even capable of seeing in three primary colors rather than two, and I unaware of any non primate mammals that can see in three primary colors.
Canada Goose Parka Avireptiles (as in, the whole reptile clade including birds) and arthropods have remained primarily diurnal and thus have as a whole much better color vision than mammals. If I recall correctly, many birds can see in four primary colors, though the champion as far as color vision is concerned is the mantis shrimp: apparently, some species can see in as many as twelve colors. Canada Goose Parka
canada goose uk outlet Torbjoern, do you have a reference for that work? Sounds possible and interesting, and canada goose jacket uk I like to know more. Most mammals have two colour vision, corresponding to our blue green. A gene doubling event in green, followed by drift into a new function, gave old world monkeys and their descendants three colour vision, so canada goose outlet canada goose outlet uk I presume there no physical reason why your enhanced mouse couldn canada goose outlet nyc be 3 colour. canada goose uk outlet
cheap Canada Goose I was just thinking of the short pathlength in canada goose outlet price the insect eye and canada goose jacket outlet toronto the fact that protein absorbs near UV, albeit rather weakly. I have read that even two colour vision can be traced to a yet earlier gene doubling event. So the cladistics of all the different optical opsins (I think there one organism with 11!) would canada goose outlet florida be a neat little problem I sure some work of this kind has been done already. cheap Canada Goose
A complicating fiddle. The genes for one of the visual pigments are located on whichever https://www.gooseyou.com of the sex genes it is that women have two of, to men one OK, canada goose outlet store quebec I worked it out ; must be the X chromosome, because Y genes trace paternity while mitochondrial DNA traces the maternal line.
Anyway, because of that, a small proportion of women with an uncommon ancestry inherit four different genes for visual pigments the 2 non x ones, plus two different alleles for closely related but different visual pigments. Which gives them tetrachromic vision, not normal trichromic vision.
canadian goose jacket At least one such woman has been identified, and when tested, her tetracromicity has been demonstrated. canadian goose jacket
canada goose clearance sale Old news about a decade ago but a cool piece of genetics. Even I looked up from my fossils for long enough to remember some bits of it. canada goose clearance sale
uk canada goose I suppose I find seven better recitations of the story, with references, the moment I post this. uk canada goose
canada goose uk black friday This canada goose outlet in new york reminds me of a Stargate Atlantis episode where the sea creature there could detect a solar flare building far enough in advance that they could hide in the shield of the city for protection canada goose uk black friday.
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