Even the would-be weightlifting champions of the Paris Olympics would find it hard to compete with such a mighty insect: The dung beetle, like Sisyphus, manages to push and carry balls of excrement which can weigh up to seven times its own weight, without losing heart. The species, named – you guessed it – Sisyphus schaefferi, is the subject of an intriguing study published on January 17 in the journal Proceedings of the Royal Society B. A team of Swedish and South African researchers, led by biologist Claudia Tocco (Lund University), deciphered how male and female dung beetles cooperate to bring their precious treasure to safety.

Once hidden, this ball of dung will be used to feed and protect the eggs laid in it. Yet, contrary to what had been believed since French entomology pioneer Jean-Henri Fabre (1823-1915) first described the beetles' spectacular combined efforts, although they do indeed work in pairs, it's not the female who pulls the ball and the male who pushes it.

What piqued Tocco's curiosity was the unique way in which these pairs of beetles cooperate. Unlike ants, for example, which can team up to carry food heavier than themselves back to their nest, "the Sisyphus pair rather roll their ball towards an unknown destination until they encounter suitable terrain in which to bury it," said the biologists.

Although ants may dash about in different directions, that does not prevent them from reaching their goal, since they all share the same predefined objective. Dung beetles do not have any predetermined objective, so they can't afford to be so disorganized in their dung-rolling choreography. Therefore, their movements are perfectly coordinated – even though they cannot see each other, as each is hidden from view behind the ball.

Thus, in their distribution of roles, the male is perched on his hind legs at the front: He walks backward, rolling the ball of ruminant excrement with his front legs. On the other side, the female leans on her front legs with her head down, and pushes the odorous sphere with her hind legs. Despite these awkward positions, the pair keep to a perfectly straight path, despite the many obstacles they often have to overcome in the South African forest.

While there may be competition between beetles on the dung heap from which they construct their ball of excrement, each couple then heads off in a different direction. This straight path thus avoids competition for food and nesting sites.

Through their experiments, the researchers found that, on flat ground, the couples were no faster than males working alone. When confronted with obstacles, however, they were able to pull ahead. For example, at the foot of a vertical wall placed in their path – ranging from 2.6 to 9.1 centimeters in height – it was the combined efforts of the male, who had started to climb, and the female, who helped the ball get off the ground, that made all the difference.

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