GENEVA – They have many names. Cattle tath, otter spraints, caterpillar frass, deer fewmets, seafowl guano. They come in countless shapes and sizes – some are even perfectly cubic. And they serve no shortage of different purposes: they can be wielded as weapons, eaten as snacks, or used to strengthen social ties. "Once you've overcome the initial gag-reflex, you'll see there's a whole new world swarming with life," says Geneva Natural History Museum curator Manuel Ruedi, who has just inaugurated an exhibition called KK.ZOO. That's "KK" as in "caca," i.e. poop.

Feces, in their most basic sense, are waste. But they're also much more. Such is the museum's creed. Some birds, like blackbirds and thrushes for instance, use their droppings -- made ​​particularly sticky because of their mistletoe consumption -- to bombard enemies that might get too close to their nests. Without knowing it, others spread the seeds of the fruits they eat via their excrement. The seeds then benefit from the natural fertilizer in which they were expelled. The cycle thus ensures that the birds' offspring have enough to eat.

For some animals, droppings also act as a genuine social network: They use feces to signify their presence, mark their territory, or look for a sexual partner. "Guanacos, llamas or camels, for example, have shared latrines," says Manuel Ruedi. "Animals belonging to the same group all poop on the same heap. By sniffing it, they can tell who's been there and when, and gather all sorts of other information." They can gather, in other words, key tidbits about the health, sexual state (in heat or not), or even emotional state of their congeners. "If one group member was attacked by a puma, there will be stress hormones in their urine," says the curator.

"Just bend down and breathe"

And even though they have a less developed sense of smell than other animals, humans — hunters and naturalists, at any rate — are also capable of reading into feces. "In the wild, we come across what animals leave behind more often than we see animals themselves. But turds tell stories," based on their size, shape, color and even smell. "Just bend down and breathe," Ruedi advises. Marten droppings, for example, have a more musky scent than do weasel feces. The river otter's spraint has a sweet smell. "It's not necessarily unpleasant," the curator says — although he adds that the waste of certain carnivores smells very bad indeed.

Manuel Ruedi started gathering this particular kind of knowledge when he was a child. "But actually, if you are in the Rocky Mountains in Canada, where there are grizzly bears and wolves, you can learn very quickly that a steaming turd means that its author is still around ... Your hunter-gatherer instincts immediately kick in."

Sometimes, naturalists end up being experts in forensic science. A sheep was killed. On the crime scene, there are several different kinds of droppings. A wolf, a dog and a fox are among the suspects. Determining which predator is the killer is a task regularly assigned to the University of Lausanne's Laboratory for Conservation Biology. In its KK.ZOO exhibition, the museum dedicates a section to just these kinds of investigations.

Making things even more complicated is that fact that a single animal can produce various kinds of droppings. Wolves, for example, tend to feed first on an animal's muscles, then the skin, next the hair, and finally the bones. As a result, they can leave four very different varieties of feces – the last, not surprisingly, is white.

Predators beware. Your droppings can betray you long after you have finished your meal. Actually, some feces don't decay at all. The exhibit contains a fossilized 200-million-year-old shark excrement. KK.ZOO also features a replica of a "coprolite": 65-million-year-old Tyrannosaurus poop. An analysis of the fossil revealed that the T-Rex had just eaten a triceratops. No doubt he didn't expect his meal to leave such a mark in history.

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Photo - Muséum Genève