The paper on chilli archaeology that I described a couple of days ago included two recent references that caught my eye, both by Joshua J. Tewksbury at the University of Washington, Douglas J. Levey of the University of Florida, and various colleagues. They add to our understanding of why it is that chillis evolved to accumulate the chemical, capsaicin, that makes their fruits pungent.
In one of those reports, published in November of last year, Levey, Tewksbury and colleagues tested the theory that capsaicin selectively repels rodents and other grain-eating mammals, which would chew up the chilli's seeds along with the surrounding fruit, while having no deterrent effect on birds, which have no teeth, swallow the fruits whole and defecate the seeds intact. They monitored wild chilli plants in Bolivia and in Arizona with video cameras, and found that only birds ate the fruits, as the theory predicts. Interesting sidelights: in past studies, lab rats frequently fed hot chillis have developed a strong liking for them, just as many humans do. And the wild species that were monitored, Capsicum chacoense and Capsicum annuum, bear fruits with a significant oil content, unlike our domesticated varieties. Oily chillis could be an interesting new ingredient.
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Levey, D.J. et al. A field test of the directed deterrence hypothesis in two species of wild chili. Oecologia 2006, 150: 61-68.
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