21 January 2013

And after they kiss etc., they make little banovados

"why an avocado ripens when you give it the company of a banana in a bag (it's the pheromones)"

That is part of the selling spiel on the back and online for the highly touted and very worthwhile What a Plant Knows: a Field Guide to the Senses, by Daniel Chamovitz, a Scientific American book published in 2012.

from the blurbs
"...scientifically accurate..." - Professor Stephen D. Hopper, director, Royal Botanical Gardens

Hormones, pheromones, what does the difference matter?
Dr Chamovitz does explain inside the book that the ripening secret is of course, ethylene, which has been called the 'aging hormone in plants' and 'the ripening hormone' in the pages of Scientific American. But if one learns the pheromone factoid and mashes it with other information, as we tend to, one can end up then adding up both to Learn the Secret of Secrets. Age+=IrresistibleAttractiveness+. Pile on those years!

The book itself is well written, the concentration on plants' reactions quite fascinating. The wide praise that What a Plant Knows has garnered is well deserved. So either it's a shame that this factoid is sitting in pride of place to no good end, or I'm just making a fool of myself, displaying my ignorance. I'm no scientist. So my question to Dr Chamovitz is: Is this a factoid you wish to stand by: "it's the pheromones"?

If not, what's going on?

Pop trends in pop sci books
The reason I ask this question is that I see a trend in popular science books, to churn them out and damn the facts, instead, filling the minds of innocents with factoids that are sensational, but wrong, not that anyone's complaining. One example of this is the text of the book Fifty Animals That Changed the Course of History by Eric Chaline, who has also written in this series, Fifty Minerals... and Fifty Machines....

This is an ambitious and growing series from Firefly Books, every one looking like a book to trust, use as a reference, and above all, to have around for children to learn from. Filled with pictures that illustrate the topics excellently, and very attractively designed. However, the information itself is where the series fails. Here's an excerpt from Fifty Animals... by Chaline, about the Camel:

"In the nineteenth century...the US Army had its own camel corps for transportation in the Southwest during its war against the Native Americans in Florida." 

Because most nonfiction books are packaging exercises as this series is, the going cheap on the actual text here could be forgiven, if it weren't a series that otherwise looks so good that, as my local library did, buying this series is as much a no-brainer must-have to a public library as encyclopedias once were. But encyclopedias were like beehives, buzzing with many authors, in a time when time meant time, and not no time. What bugs me most is that sloppiness of information when presented so attractively and sensationally, corrupts young minds (old ones tend to forget it, so I'm not so worried about the wrinkled browed). And it's odd, too. Books that are supposed to be definitive sources are most reliable when they're written for the wrinkle-browed, who love nothing better than waving their sticks at false factoids, so there's more care put into books for those who are no longer young and supple.

Ah well, I think I must be showing my pheromones.


Danny Chamovitz said...

Hi Anna,

Thanks for the question about the pheromone "factoid". So what is a pheromone? Pheromones are hormones capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual. Most hormones work inside the body, being produced in one part, and acting in another. Hormones are small chemicals that communicate physiological states. Animals produce animal-specific hormones, and plants have plant-specific hormones. Ethylene is a volatile plant-specific hormone that is given off by one plant, and affects the "behavior" (e.g. ripening) or another plant.

Danny Chamovitz

anna tambour said...

Thank you very much for taking the trouble to write this explanation, Dr Chamovitz. I had thought that the pheromones, to be considered so, must be released to affect other members of the same species, or acting as a kairomone, purposely passing messages between species. So forgive me for still being confused about the plant hormone ethylene, when it ages fruit from other species. How is it considered a pheromone in the case of one species' release of this hormone influencing another incidentally? I'm sorry to be sticky on this, but I can see that if this is true, then many other chemical releases (naturally or through intervention) could be considered pheromones when they influence members of another species. Perfumes could be sold as 'pheromones', when in fact, humans can't smell human pheromones. Or am I just being obtuse? Please bear with me and do explain. I am truly interested, because you are expanding knowledge, and perhaps I'm stuck in obsolete definitions combined with my own obtuseness.

Danny Chamovitz said...

I think the trick is not getting stuck in dry definition. If you understand the intention, then that is good enough. Remember, even in classic animal pheromones, we don't "know" if human s can influenced by other pheromones given off by other species (I don't know if its even been checked). When oranges give off ethylene they are "intending" to effect other organges. The fact that we put them in a bag with other fruits is our craziness.


anna tambour said...

Unfortunately, scientific terms are best used when they are used with some precision, which isn't the same as 'dry definition'. I was not meaning to say that humans are influenced by animal pheromones, only that by taking out the basic meaning of the word, it can be said to mean anything and therefore becomes meaningless, not aiding comprehension and communication, but blurring it. 'Our craziness' has nothing to do with the purpose of the hormone, so should have no influence on the term. As for the 'intention', that is what I have questioned. There is no intention between species here, so the intention is purely that of the communicator, and that is what I questioned in the first place.

Therefore, if it is fine to say that this hormone is acting as a pheromone to another species purely coincidentally, then by the same token, I don't know why it wouldn't be just as dandy to say that when we are breathing, we are photosynthesizing, because we are restoring our tissues.