Once in awhile I find something that piques my interest that is different from the usual WUWT fare. This was one of those. I like this fellows blog because 1) I like hot peppers 2) I enjoyed his writing style 3) Given all the hot talk on climate lately, this seemed like a good topic to cool everybody off with – Anthony
Hot Peppers – Why Are They Hot?
From a Blog around the clock by Coturnix
Some plants do not want to get eaten. They may grow in places difficult to approach, they may look unappetizing, or they may evolve vile smells. Some have a fuzzy, hairy or sticky surface, others evolve thorns. Animals need to eat those plants to survive and plants need not be eaten by animals to survive, so a co-evolutionary arms-race leads to ever more bizzare adaptations by plants to deter the animals and ever more ingenious adaptations by animals to get around the deterrents.One of the most efficient ways for a plant to deter a herbivore is to divert one of its existing biochemical pathways to synthetise a novel chemical – something that will give the plant bad taste, induce vomiting or even pain or may be toxic enough to kill the animal.
But there are other kinds of co-evolution between plants and herbivores. Some plants need to have a part eaten – usually the seed – so they can propagate themselves. So, they evolved fruits. The seeds are enveloped in meaty, juicy, tasty packages of pure energy. Those fruits often evolve a sweet smell that can be detected from a distance. And the fruits are often advertised with bright colors – red, orange, yellow, green or purple: “Here I am! Here I am! Please eat me!”
So, the hot peppers are a real evolutionary conundrum. On one hand, they are boldly colored and sweet-smelling fruits – obvious sign of advertising to herbivores. On the other hand, once bitten into, they are far too hot and spicy to be a pleasant experience to the animal. So, what gives?
Back in 1960s, Dan Johnson had an interesting proposal he dubbed “directed deterrence” which suggested that some plants may make choices as to exactly which herbivores to attract and which to deter. Hot peppers are prime candidates for such a phenomenon. What is hot in peppers is capsaicin, a chemical that elicits a sensation of pain when it bind the vanilloid receptors in the nerve endings (usually inside the mouth) of the trigeminal nerve. As it happens, all mammals have capsaicin receptors, but it was found, relatively recently, that birds do not.
To test that hypothesis, Josh Tewksbury used two variants of hot peppers – one very hot (Capsicum annuum) and the other with a mutation that made it not hot at all (Capsicum chacoense) – and offered both as meals to rodents (packrats and cactus mice) and to birds (curve-billed thrashers).
All species ate the sweet kind about equally. When Josh offered them identically prepared meals made out of the hot stuff, the two rodents refused to eat it while the birds happily munched on it.
The study appeared in 2001 in Nature (pdf) and I saw Josh give a talk about it at that time as he was joining our department to postdoc with Dr.Nick Haddad. While my lab-buddy Chris and I gave him a lot of grief in the Q&A session on his lenient criteria of what constitutes a “hungry animal” (he needed them to be hungry for the feeding tests), still the main conclusions of the study are OK.
More importantly, it really happens in nature. Mammals avoid hot peppers out in Arizona where Josh studied them (and made videos of their behavior), but the birds gorged on peppers. When he analyzed the droppings of rodents and birds fed peppers, he saw that seeds that passed through avian intestinal tracts were fully fertile, while seeds eaten by mammals were chewed, crushed, broken or semi-digested and not fertile at all.
Additionally, the thrashers tend to spend a lot of time on fruiting shrubs of different kinds. While there, they poop. The hot pepper seeds in the droppings germinate right there and this is an ideal shady spot for them to grow.
What a great example of (co)evolutionary adaptations. Next time on this blog, the second Big Question: Why do we like to eat hot peppers?
UPDATE: I’ve added this chart of Pepper “hotness” below, to help you gauge what to eat and what not to eat (or spray). – Anthony
Source: Calbob.com and Wikipedia’s Scoville Scale
hareynolds-
Gosh, all that travelling and still making crass generalisations, eh? Well done, I suppose.
This cannot be that new of a concept. I read many years ago that adding hot sauce to bird food will keep squirrels out of your bird feeder but will not deter the birds.
Mike
Mike Bryant (17:33:43) : Any plant or creature that man loves and/or consumes will never have to worry about extinction. Can you imagine cows becoming extinct?
Would that this were true… but we are fickle with our love. And unfortunately there are fads in foods and farming, like everywhere else in life. When an animal or plant ‘goes out of style’ it often goes out of existence. While this is typically at the variety level, it isn’t always. There is a dedicated band of folks who try desperately to save the old varieties (especially in the face of mechanized monoculture practices and GMO seed monopolies ) but hugh numbers of varieties are still lost, and with them thousands of years of genetic selection for special traits. For example, there is one indian corn that has a tap root and grows well where their is very little water in the desert southwest.
If you would like to help, or even if you just would like to try some peppers you’ve never heard of before, or remember from your youth, (or any other vegetable for that matter) these folks are a good place to start:
http://www.seedsavers.org/
The current varieties of peppers the central farm is offering are:
http://www.seedsavers.org/Items.aspx?hierId=90
It’s basically a peer-to-peer network of gardeners saving a lot of different seed types, with a central coordinating resource.
BTW, dried seeds in a glass jar in the freezer will keep for years to decades. (There are some seeds, called ‘recalcitrant’, where this doesn’t work. These are often the most threatened with loss and many are fruit trees. See:
http://en.wikipedia.org/wiki/Recalcitrant_seed )
For an example of the risk a critter takes when it throws in with people, consider the draft horse. Very few remain (mostly on Amish farms and in beer commercials…) thanks to the tractor. Many varieties have been lost. Draft oxen are still around (largely in Asia) but dropping in numbers. Many unique native rice varieties are disappearing under the pressure from newer genetically modified varieties (that are often dependent on herbicides and pesticides that the older types did not need). And with them goes thousands of years of genetic selection for local land and pests. It’s a long list…
Then there are the Dexter cows (and related). Small cows just the right size for a farm family. Not interesting to industrial milk producers and disappearing with the family farm that grows all their own food. Same thing with ‘mixed use’ animals of all sorts. You now find ever more wool or milk or meat sheep varieties, and ever fewer animals that are OK or pretty good at all of them. Centralized mechanized production wants one optimal product, not a package of pretty good products matched to a subsistence farm family needs.
Or just consider the parsnip. At one time they were on just about every table in America (thus what used to be a common phrase “Kind words butter no parsnips!” meaning roughly “You talk sweet, but talk is cheap, show me what you really do.”) They are now reduced to one little square in the grocery store, hanging on due to a band of ardent parsnip lovers (like me!). The number of varieties has plummeted apace. BTW, just peel them like a carrot, cut in to pieces, and boil (with the lid off!) for about 15 minutes. Drain, add butter and salt. Yum! There is a slightly ‘piney’ flavor that leaves with the vapors, but stays if covered, that’s why the lid stays off during boiling…
Or the dandelion. Once a staple of dandelion wine and herbal medicine, now attacked with herbicides everywhere. Sigh. No, they are not threatened with extinction, too hardy, but many other medicinals are threatened due to the move to modern medicine. ( I do have a packet of Italian dandelion seeds in my seed freezer. It seems folks in Italy still see them as salad fixings… and have selected better tasting varieties.) BTW, the bitter component is the medicinal part. It is being studied and been shown to really work. (i.e. tested in labs by PhD’s not just anecdotal stuff… See:
here for example.)
And finally, the mangle beet. Almost extinct. They were grown by the millions to feed to the cows and draft oxen on farms. A few survive (again mostly in Amish hands) as a way to store cattle food over the winter in harsh climates. It is said that the milk tastes better when the cow is fed beets (by my Dad and others from that line of the family). I don’t know, because we left the farm 80 years ago… before I was born… and the practice is dying along with the migration to mechanized monoculture.
BTW, a ‘new law’ in the EU threatens private seed conservation by requiring government sanction for any seeds. Centralized power and authority stamping out choice, and with it varietal diversity. Same thing that is happening with energy choices…
Steven Horrobin
I think the favored Pommey phrase is “Flash Git”.
Sorry for the “Pommey” bit, too much time spent with ANZAC citizens [I can actually spell Gallipoli, but only after a few stubbies].
I was actually given a copy of the original “Flashman” novel as a wedding present by one of my mates. I’m quite proud of that.
My point is, don’t give intent to plants. We can speculate on many things on how a chemical reaction changed due to external stimuli. Plants do have mechanical and chemical reactions to external stimuli but those are very limited and usually once the boundary is reached and passed, the plant dies.
In the case of animals with brains, most of them will built or seak shelters and find food in order to survive. They use their brains and habilities they learned. They have a fighting chance to survive, even if slightly outside their limits. Of course for most species, the smartest survive. I am not quite sure anymore if this applies to humans because just like the elephant that goes over the cliff, humanity is being led over a cliff and most are following. Humans don’t adapt anymore, they adapt their environment.
This is not the case for plants. If you can ever prove that plants have intent or awareness (or fool the people to think so), you will surely get a nobel price just like Gore did.
But to come back to the peppers, maybe instead of saying the plant decided to be like that in order to survive, maybe we should look at the kind of environment they can grow in, the chemicals in the soil, where they have originated, the climate at the time, etc. That would be a start.
I totally agree with Polazerus, we are adrenaline addicted. In a way, we like pain. Did you know that the same chemicals and brain activities when in pain are also identical to that when having an orgasm? Scans and chemical analysis have shown that. The difference is only how we interpret the situation. The funny things about capsaicin is that it is purely sensorial. There is no damage to any tissue, but we are in real pain when we eat hot peppers and we decode this pain as “good” because if we thought it was real pain, we would not touch the stuff.
janama (19:08:59) : BTW regards the possums. If you feed your possums stuff they like – like fresh apples etc they will leave your garden alone.
My garden used to be ravished by snails every year. ( I also used to be grumpy at The French for releasing the little buggers in California … until I found out that our native mollusk was the slug and that snails compete with them… I really don’t like slugs!) For decades I dumped toxic snail death all over my garden. It sorta worked. Once I ‘hand picked’ a gallon or two of snails from the crevasses of the fence and under things. Helped for about half a season.
One year I finally gave up and stopped using any chemicals (other than the occasional fertilizers). Next year a ‘possum moved in under the garden shed. We shared the garden a bit. I like ‘possums. She had a family (the little ones are incredibly cute!)
Two things happened.
1) ‘possums just love snails. I have not seen a snail since. My net garden production has gone up, not down. Especially leafy things that the snails used to just destroy.
2) When my finicky cats decide that the cat food can was opened 2 hours ago so the food is not fit for them, rather than being grumpy about it, I set the plate out near the shed for the ‘possum (they are omnivores). Now it’s not “wasteful” it’s ‘possum food. Same thing with some of the stuff my family decides is not worth eating. The ‘leftover leftovers’ go to the ‘possum family. I’m happy because we are ‘no long wasting food’, my family is happy because I’m not nagging, the ‘possum is happy with a steady high energy diet, and I have no snail problem. Works for us… And as long as the feedings are sufficient, the garden is last on the menu… though they did take my cauliflowers (left the kale and collards. Guess they weren’t that hungry! )
BTW, last time I saw a ‘possum in the yard, it was big! 2 x the size of a cat or maybe more. They do really well on ‘leftovers’. We’ve had about 4 litters I think, but it could be more. They like to live under sheds and decks where predators can’t get to them…
So if you have a ‘possum problem, call it a feature and enjoy a snail free gardening experience.
BTW, I’ve put up my ‘first cut’ at GIStemp STEP1. That’s the Python step. More will be added over time (this is just the overview, I’ll post the Python listings later). It’s technical and a bit dry (coding / programming types will like it I think) not for everyone. For anyone who’s interested, you can look at:
http://chiefio.wordpress.com/2009/03/03/step1-overview-and-sizes/
Eat some and you´ll find the ultimate truth: It hurts the way in…and the way out too!
My grandfather (Papa) used to grow Chilitepin peppers along his driveway in red Alabama clay. He ate several of them raw with every meal (yes, breakfast too). I spent every summer trying to eat just one, and although I like very hot things, I just couldn’t finish even one until I was 24 years old. These little suckers skip the tongue and head straight for the back of the throat.
Papa lived to be 92 and had a full head of hair. Maybe there’s something to eating really hot peppers! However, he was stone deaf in his later years. I claim it was from the peppers burning their way up his eustachian tubes.
Jeff Alberts (20:31:57) : I never understood the macho BS of having “hot sauce contests”. Must go along with other stupid human tricks of smoking and drinking.
One friends favorite saying is “All Scottish cuisine is based on a dare.”
Don’t know where it comes from, but Haggis was involved at least once. (Strangely, I like haggis as long as you don’t remind me what’s in it.)
I find yogurt works well to cut the heat, which is probably why it figures in so many Indian menus.
What about duck billed platypuses? Are they a mammal sensitive to chilis or a bird that is resistant?
From Iowahawk’s “It Takes a Proverb to Run a Village” …
“Do not curse the crow who has stolen your chili; tomorrow his rectum will curse the dawn”
Steven, he’s obviously never heard of Dave Lister 😉
Doh, but Dave wasn’t “fair-skinned”, in the show, anyway.
Here’s one for you — not all peppers from the same plant will have the same heat index. I’ve found this is especially true of jalapenos and poblanos, which can have a wide variance, from mild to toasty hot. Poblanos are lovely when lightly scorched on a grill, peeled and seeded, cut into strips, and added to fajitas.
It isn’t just temperature and watering — the minerals in the soil can influence the heat of the peppers, too. Hot nights are key.
After you string peppers to dry, THROW AWAY THE NEEDLE, do not return it to your sewing basket…
The fleshy hot peppers, Jalapenos and Hungarian yellows, are quite good done up as mustard pickles. Throw in a few carrot sticks for color. My daughter ate pints of the things when she was a toddler.
For damping heat, banana works well, but I prefer a nice cucumber raita.
In all my years as a farmer, I never had trouble with birds swiping peppers. I’ve never seen a thrasher eat anything that wasn’t already on the ground — they thresh the leaf litter on the ground, mainly for bugs. California Thrashers are interesting birds. I did lose a jalapeno crop to large, pale green worms back in 1977, possibly a lost colony of tomato worms.
E.M.Smith — Mangels have a superior yield per acre, though I’d rather eat a chioggia.
FatBigot (21:35:12) : Most of them had not had curry before and one was tempted by the green beans garnishing the surface of the Lamb Jalfrezi, so he scooped them up in his fork and wolfed down the lot. They were, of course, long thin green chillies.
OK, my chili mistakes stories:
Had the ‘green beans’ one. As a newbie, went into a local Thai restaurant. Ordered something random. There was a bowl of coconut soup or some such with some ‘green beans’ floating in it. Slurp, chew, swallow, pause Oh My God! Was then informed by “friend” that the chillies were for seasoning, not for outright eating…
Another time my Chinese buddy was introducing me to some good Chinese food (rather than the gringo stuff I’d order from the tourists menu). He liked it spicy. We go in, he orders what sounded to me like Gunpowder Chicken with some chinese words tacked on (that I later found out meant roughly “put on the really hot peppers reserved for folks from {particularly hot location of China}”.
Dish comes. Lots of tiny little red things in it with chicken and vegetable bits. I dig in and shovel. Whoops. Very hot, but livable. (Immediate sweat runs down forehead). THEN he tells me that I’m not supposed to actually eat the little red things, they are cooked with the dish just to flavor the rest of it… What would I do without friends… But we both ate the rest of the dish peppers and all, though I didn’t taste much but peppers.
hareynolds (21:51:15) : Now I realize that canned Jalapenos are literally kids’ stuff;
I canned my own once. Very Very hot. Waited a year. Opened some. Nothing worth noticing. I suspect that you need to do something to protect them from breakdown in canning. Vinegar and low temps? But I can say for certain that straight canning plus time just kills the heat.
The only consistent exceptions to this that I’ve seen are fair-skinned Englishmen.
Sir! I resemble that remark! (Though in fairness, only part English, the rest is an odd mix of Viking, German, Irish and a smidge of French…)
ANY peppers in a meal and I immediately begin to sweat from the top of my head down to my neck. Forehead, temples, you name it. But not one drop from any other part of me. No idea how or why.
I had a pasty English boss about 25 years ago who would break out in a torrential sweat if a drop of Tabasco touched his lips.[…]I’ve never really recovered my respect for the English since then.
Maybe this will help. A buddy and I decided to cook up our own chili recipe. We’d always used dry chili powder, so we decided to learn something about fresh. Not knowing anything the recipe we started from called for a couple of cups of Anaheim peppers (see chart at the top of this page). At the local grocer they had a long line of peppers, but no Anaheim, so we decided to just grab what looked nice. ( I think they were Serranos in retrospect ). So we’re making chili and I’m cutting them up (not knowing anything, left seeds in…). Tossed into pot of chili. Touched upper lip with tip of one finger and had excruciating pain… eyes watering. Washed, washed, milk, washed, washed…
Time comes to taste the chili. WOW hot! Ate a cup or so. We then decided it was just too hot to eat. (but ate a bit more anyway).
We took that gallon of chili and froze it in portions. For the next year or so we would add one cup of it to an entire pot of virgin chili instead of adding any peppers. Worked great! Nice and spicy! I don’t recommend it as a process, though.
Now I don’t know how hot that is ( 1/16 th of 2 cups of serranos with seeds per gallon ) but it’s about how I like it… Pasty English complexion and all…
Grew up with a Mexican kid as best friend. Ate at his house a lot. One time they had visitors over from Mexico who didn’t know me (nor speak English). They didn’t know I understood some fair Spanish… They were talking about how I was probably a wimp when it came to chili and should they trick me into eating some really hot sauce. Mama Celerina (as we all called her) made her own Chili Verde sauce from her own chilies. No idea what kind, but it was a brave person who put 1/4 teaspoon on a taco and lived.
Well, these guys decide to “cowboy up” and put 1/2 teaspoon on their tacos and do the “yum good” act after a small bite. I eyeball them. Take the spoon. Oh So Slowly put on a level teaspoon and inspect it… THEN go back for a second spoon… Chowed down the whole taco. (Now I instantly broke out in my head-sweat, and was in some pain, but declined to let it show).
Never saw a Mexican’s eyes get so wide at as that. They were astonished at this gringo eating them under the table on hot sauce… I sat back smug and waited for them to try it. Sanely, they didn’t! What they didn’t appreciate is that I had Mama Celerina’s chili sauce (in smaller doses!) on an every other day or so basis for a decade+ … I was instantly accepted by them and we had a good time from then on out.
one of the few things i miss from when i was in texas was the pickled jalapeno’s. i shocked my ex father in law, he was so “macho” but he could only eat half, i ate 2. and wasnt phased at all;-).
the best indian food is in rusholm manchester, leeds is good, bradford too but you cant beat the curry mile. I am british, and spicy food needs to be spicy, i always add a pinch of chilli powder to any of my dishes. i joked that my taste buds are dead thats why i can eat such spicy stuff
e.m.Smith did you know that brocolli is a new species. only 100 years old. the white liquid in a dandelion (uk), can get rid of warts and verruca’s if you put it on the spot.
Well I don’t think they are hot; maybe picante, but certainly not hot.
I’m told there is some sort of international scale of pepper “hotness” going up to a number like 280 (units ?)
Apparently nothing above about 30 is edible; at least not before losing your throat and tongue.
But the pursuit of such spices led to the creation of an Empire, and the addition of anew word to the dictionary; “Posh”.
It seems that when sailing out to India (tiger hunting old chap; and maybe some pig sticking), those ancient ships weren’t air conditioned, and if you were unfortunate to have a cabin on the south side of the ship; well it got pretty rancid inside there.
So if you were among the genteel,a nd the cognoscenti at the same time; you booked your passage to India to avoid a cabin on the south side.
So you booked your passage, “Port Out, Starboard Home”, or simply POSH.
And there you have it; enjoy the tigers old chap; and don’t drink the water!
Capsaicin is liposoluble, that means it is soluble in fat and is not soluble in water. This is why it is better to eat or drink something containing fat (like milk) to bring down the heat. Water does not do anything to remove the capsaicin from the receptors.
Basil (04:49:56) :
If you get hot pepper from your fingers in your eye – agony! – rub the eye with hair. Your own, if you have long locks, or someone else’s. It works – can anyone explain why? I was given this tip by a Mexican friend & pepper afficionado.
I would expect that the Capsaicin is absorbed into the oils on the hair.
Just had the windows rattle, pause, rattle… maybe a small earthquake somewhere? I’m off to check the USGS…
OT: Quakes. The last little shake doesn’t show up. Either not a quake or not enough time yet. But this map:
http://earthquake.usgs.gov/eqcenter/recenteqsus/Maps/US10/32.42.-125.-115.php
is not encouraging. Looks like the Hayward / Calaveras fault system is showing activity. I hope it’s not pre-shocks for The Big One. That system has a history of “letting go’ a few years offset from the San Andreas, and the San Andreas let go just a few years ago (partial) in the Loma Prieta quake…
If the Hayward / Calaveras lets loose, it will be a mess. One of the faults runs right through Berkeley (splits the stadium, I think) and under or near many regional medical centers…
I really really hope there is nothing to the angular momentum spin orbit coupling to quakes hypothesis… Sun going dim and quakes at the same time would not make my day…
As that guy what capsaicin does to the eyes… http://www.nationalpost.com/news/story.html?id=1351216
mercurior (11:43:09) :
e.m.Smith did you know that brocolli is a new species. only 100 years old. the white liquid in a dandelion (uk), can get rid of warts and verruca’s if you put it on the spot.
Knew about small warts, didn’t know it would work on the big deep ones.
Didn’t know about brocolli .. did know that Brussels Sprouts were very “new”. The whole cruciferous lot, turnips, cabbages and kale family has really odd genetics.
It’s been traced back to 3 parent stocks and depending on which of the three root species crossed with what you get various turnips, mustards, cabbages, etc… And that is why the rutabaga is not a turnip. It’s one of the strange hybrids. I used to have a nice chart of this but can’t find the link now. At any rate, you get double and redoubles of the genes in some of the crosses … and whole new “species” that are also sloppy with their genes.
They have a rather cavalier attitude about sharing genes across “species” and that it why it’s incredibly pig ignorant to have created “round up ready” rape seed (canola):
http://www.defra.gov.uk/environment/gm/regulation/pgs/tab3.htm
http://www.gmo-safety.eu/en/safety_science/188.docu.html
The cruciferous vegetables are healthy and have some anti-cancer properties:
http://lpi.oregonstate.edu/infocenter/foods/cruciferous/
So eat your: broccoli, cabbage, kale, cauliflower, turnips, rutabaga, mustard, choy, Napa cabbage (really more a ‘turnip’ genetically! ), radishes, collards, brussels sprouts, etc. today
(with peppers, please! It’s all for you health after all… gee, cancer prevention AND fungicide all in one! )
“The Bhut Jolokia (A.K.A. Naga Jolokia) was officially measured at over one million Scoville Heat Units (SHU) in 2006 and replaces the Red Savina Habanero (557,000 SHU, measured in 1994) as the current record holder.”
http://www.southdevonchillifarm.co.uk/shop/index.php?target=products&product_id=129
I’ve grown them, and they are FIRE on a stick!!