The Curious Task of Preserving Darwin's Beans and Butterflies

EMMA NICHOLS NEVER EXPECTED THE beans to squeak. There were 392 of them in total, each concealed within brittle paper packets containing anywhere from one to 42 legumes of varying sizes and provenances. No one had paid much attention to them for more than a century, but now the beans needed to be sorted, counted, and preserved for posterity in the digital realm.

“I devised a method of cleaning them using a polyurethane sponge between some tweezers,” says Nichols, a Book and Paper Conservator at the Cambridge University Library. Beans, it turns out, have a tendency to go flying if not carefully held, so she fashioned a makeshift silicone-tipped shaper. Essentially a brush handle equipped with tiny silicon hairs for grip, the tool kept her tiny subjects locked in place while she primped and polished. “Much to the amusement of my colleagues, [the beans] made little squeaky noises.”

Squeaky beans may have inspired a few fits of giggles, but the task of conserving organic material for digitization is serious, occasionally even dangerous work. Nichols is part of the Darwin Correspondence Project, a massive undertaking to digitize thousands of Charles Darwin’s private letters. By 2022, the team aims to release a complete archive of the late botanist’s work to the public.

“The [Darwin] Correspondence Project has been busy making text of the letters publicly available to the public for quite some time,” says Alison Pearn, Head of the Darwin Correspondence Project. “For us, digitization is an essential part of preservation and of making it accessible to as wide an audience as possible.”

Darwin penned more than 15,000 letters to scientists, academics, and, critically, amateur gardeners that influenced his findings in On the Origin of Species. The vast majority of these are available only upon request, usually to academics or researchers. More than 8,000 of them reside in the Cambridge University Library, where they’re kept under tightly regulated conditions in order to slow their decay.

“[The letters] were hugely important, not only in terms of how he got information, but also because of the specimens,” Pearn says. Beans, butterfly wings, and other botanical samples that accompanied these letters provided Darwin with an enormous trove of data. “He couldn’t have published what he published without the correspondence that he conducted with around 2,000 people all over the world. In some cases, we only have one letter, but in some cases it’s conversations, some of which went on for decades.”

Among these samples, those humble legumes played a particularly key role. “In the case of the beans, it’s a really nice example of how Darwin worked,” Pearn explains. “He was interested in cross-fertilization, the mechanisms of which were not understood.” Darwin knew he couldn’t get all the information he needed without help. In 1857, he published a short article in the Gardener’s Chronicle, a weekly illustrated journal for horticulture enthusiasts, entitled “Bees and fertilisation of kidney beans.” He concluded by asking if readers could send him information about their experience.