Chasing Bookworms: What Missing Art Can Tell You About Insects


"The Rich Man" by Cornelis Anthonisz (1541), courtesy Rijksmuseum, Amsterdam.

Between the 15th and 19th centuries, Europeans illustrated their books mainly with woodcuts. A woodcutter would etch a block of wood with an image so that when the block was dipped in ink and then stamped on a page, the areas that were cut away would leave just the white paper, and the remaining raised parts would pick up the ink and create black lines. (Here’s Albrecht Dürer’s Samson Rending the Lion as woodblock and ink-on-paper).

Those carved-out parts of the blocks and the white spaces on the paper were just as important to the art as the untouched wood and lines of ink. Empty spaces can say a lot. That’s why Blair Hedges, an evolutionary biologist at Pennsylvania State University, is so interested in certain holes that appear in many of these old books.

Bugging Out

These aren’t holes in the plots, but the artwork. Called wormholes, they’re actually the handiwork of beetles which came from eggs laid in trees and then emerged from the wood as adults, sometimes after the trees were turned into lumber—and sometimes even after a piece of wood had been carved with an image for printing. Hiring an illustrator to remake blocks affected by the bugs was expensive, so printers often went ahead and used them anyway, and many woodcut illustrations in older books are pockmarked with small circles that interrupt the ink lines. You can see some in the image above.

To biologists, those circles are trace fossils. Like a tooth mark or a footprint, they provide evidence that an animal was in a given place at one time. In this case, they pinpoint where a beetle once burst forth into the world. Hedges has used wormhole fossils from old books, maps, and art prints to study the distribution of certain wood-boring beetles over the hundreds of years when woodcuts were at the height of their use.

For a recently published study, he examined some 3000 wormholes in woodcut illustrations made between 1462 and 1899. He found that the wormholes in illustrations printed in northern Europe were round and, on average, 1.4 millimeters across. The wormholes from southern Europe were about twice as large, averaging 2.3 mm across. Many southern holes were also pill-shaped, or had “tracks” instead of being a a circle, shaped by the beetle exiting its nursery in a diagonal path instead of digging straight up and out (shown below).

Woodcut (1606) by Giovanni Battista Ramusio, courtesy Library of Congress

Going by the size and shape of the holes and what’s known about beetles’ wood preferences (some, for example, only lay their eggs in damp, rotting wood, which is not something that would be used in printing), Hedges was able to pin the holes in the illustrations on two species. He thinks the common furniture beetle (Anobium punctatum) is the likely culprit for the northern European works, and the Mediterranean furniture beetle (Oligomerus ptilinoides) for the southern ones.

Drawing the Line

The woodcut holes suggest a clear geographic divide between the beetles. Through hundreds of years of European literature and art, the two species’ ranges appear to have butted up against one another, but never overlapped.

This stark division is shocking because, today, both beetles are widely distributed through western, central, and southern Europe. There’s a lot of overlap in their ranges, and no one knew until now how their distribution was in the past, or if or how it had changed.

By looking at where and when the books were printed, Hedges was able to plot the historical dividing line between the two beetles (shown in the map below with each species’ current European range). Characteristics of its shape—like the curve south as it approaches France’s humid west coast—and the northern beetle’s sensitivity to certain environmental factors—like a combination of low humidity and high temperature—suggested to Hedges that the boundary between the two species was partly a matter of climate. As the climate changed over the centuries, though, the border might have held because both beetles prefer the same kind of wood, and they were avoiding competition with each other for it.

Broadening their Horizons

Top: historic range of two wood-boring beetles. Bottom L: modern range of the common furniture beetle. Bottom R: modern range of the Mediterranean furniture beetle. Hedges, 2012

The beetles expanded their range in the late 19th and early 20th centuries, which means that people are one reason for the fall of the dividing line, Hedges says. The beetles' expansion came during a time when increasing global trade, travel, and commerce moved infested wood around Europe and to other continents, and modern homes with carefully controlled climates might have allowed the bugs to acclimate to new areas and eventually colonize them.

And all that comes from some blank spaces in old drawings.

While the books told Hedges a lot about the beetles, he says that the beetles can teach us something about books. In situations where a book’s point of origin is unclear, he says, historians could now use the known historical range of these two beetles to determine whether a book was from northern or southern Europe, just by examining and measuring what the insects left behind.

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Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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Uncombable Hair Syndrome Is a Real—and Very Rare—Genetic Condition
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Everyone has bad hair days from time to time, but for roughly 100 people around the world, unmanageable hair is an actual medical condition.

Uncombable hair syndrome, also known as spun glass hair syndrome, is a rare condition caused by a genetic mutation that affects the formation and shape of hair shafts, BuzzFeed reports. People with the condition tend to have dry, unruly hair that can't be combed flat. It grows slower than normal and is typically silver, blond, or straw-colored. For some people, the symptoms disappear with age.

A diagram of a hair follicle
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Although there have been only about 100 documented cases worldwide, one of the world's leading researchers on the condition, Regina Betz, of Germany's University of Bonn, believes there could be thousands of others who have it but have not been diagnosed. Some have speculated that Einstein had the condition, but without a genetic test, it's impossible to know for sure.

An 18-month-old American girl named Taylor McGowan is one of the few people with this syndrome. Her parents sent blood samples to Betz to see if they were carriers of the gene mutation, and the results came back positive for variations of PADI3, one of three genes responsible for the syndrome. According to IFL Science, the condition is recessive, meaning that it "only presents when individuals receive mutant gene copies from both parents." Hence it's so uncommon.

Taylor's parents have embraced their daughter's unique 'do, creating a Facebook page called Baby Einstein 2.0 to share Taylor's story and educate others about the condition.

"It's what makes her look ever so special, just like Albert Einstein," Taylor's mom, Cara, says in a video uploaded to YouTube by SWNS TV. "We wanted to share her story with the world in hopes of spreading awareness."

[h/t BuzzFeed]

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