The Celestial Navigator

In the pecking order of God’s creatures, the dung beetle is typically characterized as “lowly,” and we don’t have to guess why. The dung beetle is most often observed walking backward with its nose to ground, rolling a ball of excrement that it has fashioned from a steaming pile of poop found in a cow pasture somewhere. Freshness apparently counts in this line of work, so the dung beetle hurries off with its prized load, traveling in a straight line. Scientists have naturally wondered how the dung beetle manages to navigate a straight course walking backward with its nose to the ground, maneuvering a ball that is often many times its own size. It turns out the lowly dung beetle ranks right up there with humans and a few other creatures in its ability to steer by the stars.

Scientists have long known that dung beetles orient themselves by the sun and moon, depending on the species and the time of day. But what happens on a moonless night? It turns out they can also make course adjustments using the Milky Way. Their eyesight is too poor to make out individual stars, but they can detect our galaxy’s ribbon of light across the night sky, at least in the Southern Hemisphere, where the Milky Way is most visible. The dung beetle’s navigation skills have been tested in the field and in a planetarium under controlled conditions.

Granted, dung beetles don’t possess the same stargazing prowess as migratory birds, which can travel thousands of miles at night by orienting themselves to constellations. Still, their abilities are impressive for creatures with a brain the size of a grain of rice. How do they do it? For evolutionary biologists, the dung beetle’s capacity to chart a course using the stars is a textbook case of natural selection in action. Competition is fierce for animal droppings, with thousands of dung beetles sometimes converging on the site of a fresh pile. It turns out dung is not only the staple of their diet but also the key to reproductive success. Males that can roll up a sizable specimen and make a quick getaway have an edge in attracting willing females, who lay their eggs in the dung balls. Of course, that doesn’t explain how dung beetles figured out how to steer a straight course by the stars in the first place – something that most humans would be hard-pressed to do. Evolutionists would say such abilities arise randomly and get passed on because they offer a selective advantage. Creationists would look at the same facts and see clear evidence of intelligent design.

Whether by accident or by design, dung beetles are noteworthy for more than their unappetizing diet and breeding habits. They are nature’s sanitation engineers, tidying up after the rest of the animal kingdom and replenishing the soil by burying waste in the ground. As you might imagine, this is no small task, and there are some 6,000 species of dung beetles hard at work on every continent but Antarctica. Many specialize in the droppings of particular animals and cannot be coaxed into altering their diet, as Australians discovered to their dismay after importing livestock that was not to the liking of the local dung beetle population. Manure began piling up in cow pastures and horse paddocks around the country until farmers introduced dung beetles from elsewhere that were willing to recycle waste that did not come from kangaroos or wallabies.

Dung beetles did not always rank next to the bottom of nature’s pecking order. Scarabs, as they are also called, were regarded as sacred in ancient Egypt. They were associated with Khepri, the god of the rising sun, who was often depicted as a scarab or as a man with a scarab’s head. Egyptians thought Khepri was reborn each morning, emerging from the earth and pushing the sun across the sky like a scarab rolling its ball of dung. Representations of the scarab were worn as amulets to ward off evil or to bring good luck, as common among ancient Egyptians as crucifixes are today in other places. We do not normally think of the lowly dung beetle as combining elements of heaven and earth, and yet where else can you find a creature that keeps its nose to the ground but never loses sight of the stars?

Marie Dacke, et. al., “Dung Beetles Use the Milky Way for Orientation,” Current Biology (January 23, 2013)

© Copyright 2004-2019 by Eric Rennie
All Rights Reserved