Red hot and almost zero nutritional value. Why do we bother with chillies?

炙熱得像團火，又沒什么營養(yǎng)價值，但為什么小小的辣椒就把我們迷得神魂顛倒呢？

Dave's Red Hot. Mother Puckers. Green Bandit. Scorned Woman. Pain is Good. Blair's Death. No, they're not rock bands. These names represent just a small selection of the brands of hot sauce available at my local supermarket.

戴夫的紅色激情（Dave's Red Hot），母親的嘴唇（Mother Puckers），綠色強盜（Green Bandit），怨婦（Scorned Woman），痛并快樂著（Pain is Good），布萊爾之死（Blair's Death），這些可不是什么搖滾樂隊的名字，它們是我在本地超市貨架上找到的辣醬品牌，而且還只是一小部分而已。

Humans, apparently, enjoy torturing themselves. Spiciness, after all, is not a flavour, not like sweet or salty or sour. Spicy means pain. The sensation of spiciness is the result of the activation of pain receptors in the tongue. According to psychologist Paul Rozin of the University of Pennsylvania, about a third of the people around the world eat hot peppers every single day. Why? Because they "love the burn". At a symposium on gastro-psychology during this year's Association for Psychological Science convention, Rozin pointed out that humans are the only species – we know about – that specifically seek out what would otherwise be considered negative events.

很顯然，人類是喜歡自虐的動物。辛辣不同于甜味、咸味和酸味，它并不是一種味道。辣是疼痛的代名詞，它是舌頭上痛覺感受器激活的結果。賓夕法尼亞大學的心理學家保羅·羅津（Paul Rozin）就認為，世界上約有三分之一的人每天都在吃辣椒。原因何在？因為他們“喜歡火燒般的感覺”。在今年召開的心理科學大會關于腸胃心理學（gastro-psychology）的專題研討會上，羅津就指出，就目前我們所掌握的知識來看，人類是唯一會去尋求某些消極刺激的物種。

Healthy, sane humans do not stab themselves in the thighs, or bathe their eyes in lemon juice. So why do we so love to assault one of the most sensitive organs in the human body, the tongue, with what amounts to chemical warfare? Chillies are unique among foods that we should otherwise not enjoy. For example, humans also have natural aversions to the bitterness of coffee or the harshness of tobacco, but those substances have some addictive qualities, which might make them desirable. Capsaicin, the compound that provides the mouth-watering punch of chillies, does not seem to have any addictive qualities whatsoever. And yet the preference for capsaicin is almost universal; nearly every culture has incorporated it into their cuisine in some way, for milllennia.

任何心智健全的正常人都不會拿刀插自己的大腿，也不會用檸檬汁去噴自己的眼睛，但為什么我們卻喜歡在自己最敏感的器官——舌頭上大打化學戰(zhàn)爭呢？辣椒是一種人類本無法享用的獨特食物。例如，人類對苦澀的咖啡或嗆人的煙草存在天生的反感，但就是這些物質會讓人有成癮性，成癮之后這些原本入不得口的東西會變得怡人起來。而賜予辣椒令人垂涎魔力的辣椒素卻不具備這樣的成癮功能。然而，對辣椒素的偏愛之情依然無處不在；數(shù)千年以來，幾乎每個民族的烹飪文化中都融入了這種辛辣的氣息。

Rozin writes:

羅津寫到：

"There are records suggesting use of chilli pepper dating back to 7000BC in Mesoamerica; they were domesticated some thousands of years after this. These fiery foods made their debut in the Old World when they were brought back by Columbus and other early explorers. In spite of their initial unpalatability, they became accepted as a basic part of the diet in many parts of the world: west and east Africa, India, south-east Asia, parts of China, Indonesia, Korea, and other smaller geographic regions, such as Hungary."

“相關記錄表明，辣椒的使用可以追溯到公元前7000年的中美洲地區(qū)（Mesoamerica）；之后辣椒被馴化了數(shù)千年的時間。哥倫布和其他探險家們又將這種熾烈的食物帶回舊大陸。在度過了開始的不適應期以后，辣椒漸漸被世界各地的人們所接受，在西非和東非、印度、東南亞、中國大部分地區(qū)、印度尼西亞、韓國以及匈牙利這樣的微型地理區(qū)域，它都被視為飲食的基本組成部分。”

Most young children, even from cultures known for their spicy recipes, are averse to capsaicin. So maybe, then, instead of actually liking the pain, we're merely desensitising ourselves: what used to be really painful is now just sort of painful.

很多小孩子——甚至是來自以吃辣而聞名的國度——卻拒絕接受辣椒素。因此有可能我們不是真正喜歡辣椒帶來的痛苦，我們只是讓自己的感覺遲鈍了：曾經(jīng)的痛苦不堪現(xiàn)在變成了若有若無。

Since capsaicin is a member of the vanilloid family of molecules, it binds to a receptor on the tongue called the vanilloid receptor subtype 1. Upon binding to the VR1 receptor, the sensation produced by the capsaicin molecule is the same sensation that heat would cause, which explains capsaicin's burn. When scientists discovered that the VR1 receptor was a member of the larger family of TRP ion channels, the VR1 receptor was renamed TRPV1. TRP receptors are known to be sensitive to changes in temperature and are likely responsible for temperature sensation. When chilli peppers are the source of the capsaicin, there isn't any actual tissue damage; but because it binds to the TRPV1 receptor, the brain is tricked into believing that the tongue truly is on fire.

辣椒素是香草酸（vanilloid）分子家族的成員之一，它會與舌頭上香草酸受體1亞型(vanilloid receptor subtype 1)結合。結合以后，辣椒素分子給人帶來的感覺與熱刺激完全相同，這也解釋了為什么辣椒素會讓人有灼熱感。科學家們發(fā)現(xiàn)VR1受體是瞬時受體電位通道（TRP ion channels）家族的一員，于是VR1受體又被命名為TRPV1。眾所周知，TRP受體對溫度變化敏感，負責感受溫度。辣椒中的辣椒素被攝入人體以后并不會產(chǎn)生實際的組織傷害；但因為和TRPV1受體結合，大腦便錯誤的認為舌頭著火了。

In 1980, Rozin and a colleague, Deborah Schiller, reported a study in which they compared the pepper preferences of Mexicans and Americans. Mexicans generally eat chillies several times per day, while Americans only eat chillies a few times a week. If desensitisation could explain our preference for oral pain, then Mexicans should show higher tolerance for capsaicin than Americans, and Americans should more easily detect capsaicin, even in small amounts, than Mexicans.

1980年，羅津和同事黛博拉·席勒（Deborah Schiller）完成了一項關于墨西哥人和美國人辣椒偏好性的研究。墨西哥人通常在一天之內(nèi)吃好幾次辣椒，而美國人在一周以內(nèi)才會品嘗幾次。如果脫敏作用能夠解釋我們對辣味的偏愛，那么墨西哥人應該比美國人表現(xiàn)出更高的辣椒素耐受性，而美國人對辣椒素的敏感性應該比墨西哥人更高。

The data only weakly supported these predictions: the differences were seen, but were not statistically significant. Another prediction made by the desensitisation hypothesis is that individual tolerance should increase with exposure, and therefore with age. Rozin and Schiller found no correlation between age and tolerance though. Experiments conducted to try to induce a preference for capsaicin in rats, using traditional reinforcement techniques, proved futile.

但研究得出的數(shù)據(jù)無法支持上述預測：差異的確存在，只是缺少統(tǒng)計顯著性。脫敏假設還帶來了另一項預測，即個人耐受性會隨著暴露次數(shù)（與年齡正相關）的增加而增加。但羅津和席勒發(fā)現(xiàn)年齡和辣椒素耐受性之間并無相關性。他們還嘗試利用傳統(tǒng)的強化技術來誘導老鼠對辣椒素產(chǎn)生興趣，但都以失敗而告終。

In the late 1970s, Frito-Lay tried to market a brand of corn chips in Mexico that had the flavour of chilli peppers, but without any capsaicin. As would be expected in a culture that actually enjoys the burn, the product was a failure. Likewise, bell peppers, which have some pepper flavour but no capsaicin, are not at all popular in Mexico.

上世紀70年代后期，菲多利食品公司（Frito-Lay）嘗試在墨西哥市場銷售一款具有辣椒風味但不含辣椒素的玉米片品牌。不出所料，在這個嗜辣國度，這款產(chǎn)品根本不行銷。另外，同樣具有辣椒風味但不含辣椒素的柿子椒在墨西哥也一點不受歡迎。

While most scientists still do not quite have a handle on the human preference for spicy foods, the best explanation comes from a mechanism called "hedonic reversal", or "benign masochism". Something happens, in millions of humans each year, which changes a negative evaluation into a positive evaluation, like flipping a light switch.

當大多數(shù)科學家對于人類喜愛辛辣食物的原因感到一籌莫展時，心理學領域的“享樂逆轉（hedonic reversal）”或被稱為“良性自虐（benign masochism）”機制卻對此作出了最好的解釋。這種情況在大多數(shù)人身上都會經(jīng)常發(fā)生，其后果是導致原先的負面評價轉變成為正面評價，就像電燈開關從一頭跳到另一頭。

Rozin writes: "If the oral receptors are sending the same message to the brain in the chilli liker and the chilli hater, then the chilli liker must have come to like the very same sensation that the chilli hater, the infant, and nonhuman animals find aversive. One gets to like the burn." Only humans seem to be able to derive pleasure from the negative sensation itself. Animals have been trained to endure self-harm, but only within the context of positive reinforcement.

羅津寫到：“如果嗜辣者和憎辣者在接觸辣椒以后，其口腔受體向大腦傳遞的訊息是相同的，久而久之，嗜辣者會漸漸喜歡上這種令憎辣者如嬰兒或非人動物感到厭惡的感覺，即那種火燒般的感覺。”只有人類會從負面感受中獲取快感。雖然動物在被訓練過以后能夠承受自傷行為，但這種承受能力也只能體現(xiàn)在正強化的環(huán)境中。

Perhaps we seek out the painful experience of snacking on chillies while consciously maintaining awareness that there is no real danger to ourselves. After all, people seem to enjoy – and actively seek out – many other sensations that are otherwise undesirable but are ostensibly safe: the sensation of falling provided by rollercoasters or skydiving, the feelings of fear and anxiety while watching horror movies, the physical pain experienced upon jumping into icy water, or even the feelings of sadness that come while watching a tear-jerker. Perhaps it is this cognitive mismatch itself that provides the thrill: like strapping into a rollercoaster or popping Hostel into your DVD player over and over again, the burn of capsaicin only seems to be threatening.

也許我們從吃辣椒中獲取痛苦體驗的同時，也清醒的意識到這種刺激對我們自身不會有真正的危險。畢竟，人們似乎很享受——甚至會主動獲取——一些并不愉悅但明顯安全的感覺，如坐過山車或高空跳傘產(chǎn)生的墜落感，看恐怖電影帶來的恐懼和焦慮感，跳入冰水經(jīng)歷的生理疼痛，或觀看苦情劇時伴隨的悲傷感。也許正是這種認知上的無法調和提供了興奮的真正來源，綁在過山車中起起伏伏，一遍又一遍的將恐怖片放入影碟機中，讓舌頭感受辣椒素的熱情火焰，這些行為都是看上去充滿了危險。

Want a thrill? Go out and buy yourself a bottle of One Fuckin' Drop At A Time Hot Sauce. It comes with an eye-dropper for portion control. Benign masochism, indeed.

想刺激一下？出門去超市買上一瓶“一次一滴多滴辣死不負責牌辣醬（One Fuckin' Drop At A Time Hot Sauce）”，附贈滴管以控制取量，這樣才能達到良性自虐的效果。

Jason Goldman is a developmental psychologist and blogs at The Thoughtful Animal