Meanwhile, smell biologist Tim Jacob of Cardiff University in Wales, says that rotten egg smell is a good example of the vibration theory's appeal. Sulfur is a chemical hallmark of rotting organic material—something that is dangerous for us to eat. And molecules containing sulfur almost always smell horrible to us, he says—just as should be the case if evolution worked properly to favor our survival.
But there's no single shape or simple chemical property that sulfur universally confers to every kind of odorant molecule. On the other hand, sulfur does add signature vibrations to a molecule that a molecular vibration–sensitive nose might detect. "I do all my research without needing to know which model most accurately describes what's going on," Jacob says. But, he says of the vibration theory, "from a biological point of view it has great interest."
And that keeps fans of this fight watching and wondering: Which side will ultimately score the knockout punch? And who will need the smelling salts?
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4 Comments
Add CommentThe sulfur example is a good one, but not so the deuterium experiment. Deuterium behaves differently from Hydrogen a lot more than in "vibrations". Hydrogen bonding is much reduced in molecules with deuterium substitution, so much so that heavy water is a known citostatic agent, disabling the formation of the mitotic spindle. Hydrogen bonds play a very important part in molecular recognition so this effect can be explained by both theories...
Reply | Report Abuse | Link to thisThe vibration theory makes sense to me since we sense energy. We see wavelengths/vibrations of light. We hear wavelengths/vibrations of air, water and such. We feel wavelengths/vibrations of heat, motion and pressure. It makes sense that we smell and taste vibrations. Our "five senses" are variations in our "sense of survival" in that we are sensing the world/energy/vibrations around us.
Reply | Report Abuse | Link to thisReplacing hydrogen with deuterium can affect the conformation of the molecule to a small extent. It can shift the position of equilibrium if a molecule has two confirmations for example. This is because the amplitude of vibration of a C-D bond is less than a C-H bond, therefore a CD3 group takes up slightly less room than a CH3 group. Bonding to smell receptors depends on shape and size, so the molecule with CD3 groups can fit into the receptor more snugly or not snugly enough (obviously this depends on the given receptor and incoming molecule pair). Therefore it wouldn't be totally unexpected on the standard lock and key / receptor and incoming molecule if the smell changed a bit. So sorry, but whether or not the change in smell occurs, it does not prove this vibration theory, as it would cause changes in both cases.
Reply | Report Abuse | Link to thisThe scent of candlewax is so familiar, it must be from the start combined with everything. We came later.
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