Themes of Parasitology: San Bushmen

Why We Like It Spicy

A spicy food lover? Are your taste-buds just

attracted to the flavor or is it something else? Paul W. Sherman and his colleagues have taken an evolutionary approach to the reasoning behind various groups’ love for spices. To clarify, “spice” is a culinary term that refers to a variety of dried shrubs, vines, trees, aromatic lichens, roots, flowers, seeds, and herbaceous plant roots [1]. Each spice contains a variety of “secondary compounds” or phytochemicals which have evolved in plants to aid in protection against insects and other life forms that may prey on the plant [1]. Sherman’s theory states that depending on their climate, humans have evolutionary acquired the desire for spices not only for their flavor, but for their antimicrobial activity and ability to combat food-borne illnesses. Stemming from this hypothesis are multiple predictions: 1) spices should exhibit potent antimicrobial properties 2) geographic regions with the warmest climates should show the greatest use of spices, as these regions are threatened more by food spoilage and 3) recipes from hot climates should impede a larger proportion of bacteria than recipes from cold climates [1].

What’s the big deal? Antimicrobial properties!

Thirty spices were tested and all were found to kill or inhibit at least 25% of the different bacteria they were tested on, while half of the spices were found to kill or inhibit at least 75% of the bacteria [1]. The most potent spices revealed to be garlic, onion, allspice, and oregano as they inhibited or exterminated every bacterial species tested [1]. This is a comforting statistic as it is more likely for bacteria to be the cause of a food-borne illness outbreak than yeast or fungi and the tested bacteria are found worldwide [1].

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Don’t believe in the power of spices yet? Perhaps the San people will help change your mind.

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The San Bushmen are a group of nomadic hunters/gatherers in the Kalahri desert in southern Africa whose diet consists of only spicy foods (mainly plants), yet exhibit great health [2].

So, should Icelandic people be rushing to the local supermarket and gathering spices? No, they need not worry. Sherman states there’s no need for them to use spices as a meat left outside overnight would freeze, slowing the accumulation of bacteria [3].

Looking All Over the World

Sherman and Billings looked at “traditional” meat-based recipes worldwide and tabulated what countries used what amount of spices per recipe in order to determine if there was a pattern in spice use [1]. These results were hard to analyze. In another approach, they focused on the annual temperature of geographic regions. Their assumption was that a country’s annual temperature should be proportional to its meal spoilage rate. Thus, their prediction was countries with higher annual temperatures should use more spices in their recipes. Their prediction proved to be true. Results of countries showed as the average annual temperature increased, the number of spices used significantly increased, especially in spices that are highly effective in inhibiting bacterial species [1].

Variation in Food Poisoning Rates

In their research, Sherman and Billings compared the number of food-borne illness cases between Korea (whose recipes traditionally contain spices) and Japan (whose recipes traditionally don’t contain spices). Results showed between 1971 and 1990, food poisoning affected 29.2 out of every 100,000 Japanese people and 3.0 people out of every 100,000 Koreans [1]. Although there are additional factors to consider as to the reasoning behind the statistic, this result largely supports the theory that spices reduce food-borne illnesses.

Let's Cover All Bases

Sherman and Billings also explored other possible explanations for regional spice use. This included the ability of spices to hide a putrid flavor or odor.

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But if this was the case, then evolution would lean towards us eating foods infested with disease-causing microorganisms [4]. Thus, the first alternative explanation was debunked. The other alternative explanation was spices have uses besides fighting microbes, such as aiding in digesting, regulating metabolism and delaying diabetes and heart disease [1]. Although some spices exhibit these beneficial effects, a good amount does not, so this cannot be the primary explanation behind regional variance in spice use [1].

Let's Wrap it Up

With all of this evidence, it is difficult to ignore the impact of spices, as well as Sherman's reasoning behind regional variation of spice use. So think twice before you eat a meal with little to no spice. If you’re not going to do it for your taste buds, at least do it for your intestinal tract.