Odder than odd!

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In the dark days of winter…

We need a pick-me-up. Let’s take a guided tour of some amazing — and actually important — science results from the year just passed. What is the unseen levy of leaning? Who lives in your belly button? What are the culinary quirks of dung beetles?

Dung beetle says: It’s dang delicious!

It’s work that somebody had to do: Scientists at the University of Nebraska explored the culinary preferences of dung-eating beetles — the janitorial janissaries of the arthropod army.

ENLARGE

Two broad, flat beetles roll a ball of dung across sandy soil.

Photo: John Friel
Two dung beetles roll a ball of dung in Odzala National Park, Republic of Congo. Dung beetles distribute dung (and therefore nutrients), serving as a first step in nature’s comprehensive recycling system.

We care (at least, somebody cares!) because when exotic animals (such as the ostriches, antelopes and emus at game farms) enter an ecosystem, the local cleanup crew may lay down their plungers.

You don’t need a Ph.D. in plumbing to understand that a fecund fountain of feces makes a mess of that ol’ home on the range. In Australia in the 1700s, native dung beetles turned up their probosci at the manure left by cattle imported by European settlers, leading to an outbreak of flies and parasites.

Using dung and carrion as bait, the Cornhusker scientists captured more than 9,000 beetles in 15 species over two years. They found that omnivore offal attracted the most beetles.

Why? Omnivore dung, including the human product, rates a “10” on the stink-o-meter. And that brings on legions of these gentle janitors.

The only sad note: Chimpanzees edged humans by a nose as durn-delectable delicacies for the dung dragons.

Separation anxiety, placental edition

Just like everything else alive, bacteria need a niche. One long-ignored condo forms when the placenta is severed just after birth.

ENLARGE

Dense cluster of yellow dots against brown background on agar plate.

Staphylococcus bacteria can cause serious disease, but Staphylococcus epidermidis (shown here) is usually a first line of defense against skin disease. When oxygen is scarce (like deep in your belly button!), S. epidermidis switches to fermenting sugars. Ecch: are you brewing “navel wine”?

You read that right. We are blathering about the belly button, which has become a bountiful bacterial bestiary.

A citizen-science project called Your Wild Life has been using giga-speed sequencing of the genetic code to examine microbes retrieved from human belly buttons.

The first 60 button-loads held 29 to 107 types of bacteria apiece — for an average of 67 per button.

The findings support an axiom of tropical ecology – that the most common species usually have the largest number of individuals:

Six types of bacteria (0.3 percent of the strains discovered) lived on more than 80 percent of the buttons;

These six strains accounted for one-third of the microbes found in the project.

ENLARGE

Pint glass full with dark beer, topped by white foam.

The Why Files
Barkeeps take note: Patrons will likely under-estimate the percentage of alcohol in this fine beer while leaning to the left.

In tropical forests, the dominant species, or “oligarchs,” tend to occur in large numbers, and the authors found that same deal beneath the belt buckle: “Thus the hypothesis that ‘oligarchs’ dominate diverse assemblages appears to be supported by human-associated bacteria.”

Want to advance the cause of science? Your Wildlife is set to dig into the human armpit. We’re just sayin’…

Which way do you lean?

Scientists have found a novel way to put a thumb on the scale: asking people to estimate size, weight, even the percentage of alcohol, while standing on a Wii balance board. Even when the angle is imperceptible, undergraduate subjects make smaller estimates while leaning leftward.

In a game, subjects were asked to estimate a quantity about dozens of objects. The estimates were systematically lower when the person was leaning slightly to the left — even when the left leg was bearing only 52 percent of their weight.

The results support the idea that we mentally envision numbers as lined up with the smallest ones on the left. Oddly, the bias was so strong that it worked even though the people did not know they were leaning!1

ENLARGE

Ball of bees wrap around invisible hornets.

Yokohama, Honshu Island, Japan, Takahashi
Japanese honeybees (Apis cerana japonica) form a “bee ball” that engulfs and heats two hornets (Vespa simillima xanthoptera).

Who will be the hottest bee?

Imagine, for a moment, being a honeybee. You have an enviable defense down south, in your organic, butt-mounted stun-gun. But some enemies have evolved a hard, stinger-proof shell that prevents your chemical artillery from injecting its toxin.

If such an insect, say a giant hornet, is attacking your hive to eat your larvae and pupae, how do you protect the all-important next generation?

You could cook your enemy — if you are lucky enough to be a Japanese honeybee. These bees form a ball around a hornet with about 500 of their sisters, then vibrate their wings (which is how honeybees warm their hive over the winter). When the temperature reaches 47°C, the hornet will croak.

Sisterhood is powerful, as they used to say.

Researchers have just found that Japanese honeybees use a temperature-monitoring gene to shut down the oven before the bees commit suicide.

In other words, evolution is working to protect the bees from being harmed by a defense perfected through evolution.

ENLARGE

A map of London and environs resembles a snarl of spaghetti.

The center of this mess includes “the Knowledge” that London cab drivers must master before receiving a license.

Hack Hack: The brain of a cabbie

Physical work makes a muscle bigger. Does mental work do ditto for a brain? It’s a common-sense idea, but gnarly to prove. Now we get a positive response from a five-year study of London cab drivers.

ENLARGE

Chicken, tawny brown with white speckles, faces right, with wild crest of feathers atop head.

This Buff Laced Polish cock apparently knows a pretty female (human) face when he sees one. How come people (or at least, college students) look for the same type of pretty face as chickens?

Several years ago, Eleanor Maguire of University College London poked the skulls of experienced cabbies with an MRI and found an enlargement in the back of the hippocampus, a structure involved in memory.

But was the bulge cause or the effect? Did only people with a huge hippo’ pass the rigorous cabby exam, or did the need to memorize a meandering maze enlarge the hippocampus?

We didn’t know it either, but in order to get a license, London cab drivers must spend years “cabby cramming,” learning roughly 25,000 roads and up to 20,000 locations.

So Maguire measured, the brains of 79 applicants when they began training, and years later found enlargement in the hippocampus among 39 who passed the cabby test, but not among a control group, or those who flunked the test.

No free lunch department: those who passed the test were less able than the others to link objects and locations, likely because the front of the hippocampus was smaller than the controls.

Chicks pick pretty people pix!

It’s the standard explanation for mating choice: people seek attractive mates because evolution has driven them to unconsciously link physical beauty with health and reproductive capacity.

We didn’t guess birds would have the same preferences as college students — although we’d admit that certain college students seem on the intellectual level of fancy fowl…

In a study, the people chose the nicest face using a keyboard. Chickens chose by pecking at the screen.

The researchers concluded that the preference for attractive faces is hard-wired into vertebrate nervous system and does not reflect adaptations unique to particular species.

Probably. “We cannot of course be sure that chickens and humans processed the face images in exactly the same way,” the researchers revealed. “This leaves open the possibility that, while chickens use some general mechanism, humans possess instead a specially evolved mechanism for processing faces.”

At least the study explains why, every time we see a pretty face, we feel a compulsion to peck at the computer screen!

— David J. Tenenbaum

Terry Devitt, editor; Emily Eggleston, project assistant; S.V. Medaris, designer/illustrator; David J. Tenenbaum, feature writer; Amy Toburen, content development executive

Bibliography

  1. Leaning to the Left Makes the Eiffel Tower Seem Smaller: Anita Eerland et al, Psychological Science OnlineFirst, November 28, 2011, doi:10.1177/0956797611420731