email a friend iconprinter friendly iconMimicry
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Of course, even the most cunning of nature's caricatures have no narrative mastermind behind them. Mimicry exemplifies evolution by natural selection, the relentless struggle in which parents spawn a diversity of offspring that chance and nature's cruel eye for weakness shear almost clean away. If your slight resemblance to bird dung gives you enough of an edge that you survive to breed, your progeny may inherit your lucky guano cast. Maybe one will even top you as a droppings imposter, and within a few hundred generations the trait will have spread through the whole population and be the gold standard for your kind.

Mimicry also reveals just how messy evolution can be, how ad hoc and make-do. For example, Ximena Nelson and Robert Jackson report in the Proceedings of the Royal Society on the dilemma of the male Myrmarachne, a jumping spider. Like a number of the world's jumping spiders, these arachnids have evolved to look like ants, a strategy that plays into the antipathy many predators have for the aggressive, noxiously armed, and ecologically dominant social insects. But the male spiders have a problem with the basic strategy, for mating rituals demand that they sport elongated mouthparts, which could detract from the overall antlike effect. Evolution has hammered out a compromise: Whereas the female spiders look like ordinary ants, the males with their enlarged fangs have come to resemble ants carrying bundles in their mandibles, as worker ants sometimes do. Ingenious, yes, but not perfect. It turns out that although the male jumping spiders are as effective as their female counterparts at deterring the generally ant-phobic among hunters, the males alone fall prey to predators that target ants least likely to fight back—those encumbered with bundles.

Scientists are particularly intrigued by imperfect mimicry, where one organism only vaguely resembles another. In some cases, the crude form may indicate a lineage newly embarked on the mimicry path, when evolution has only begun to hone the simulation. In other instances, the disjunction is a result of the mimicked species pulling away from its unwanted copycats. If the warning colorations that you have evolved to advertise your hard-won unpalatability are mimicked by too many edible free riders, your brand name will be cheapened and lose its protective value.

Mimicry can also be a great way to preen, or learn, or make a new friend. Among songbirds and humpback whales, competing males seem to imitate each other's songs. And some dolphins duplicate each other's flying leaps. Parrots are masters at parroting, and ape is what the great apes do, which is why orangutans can learn to cook pancakes and chimpanzees to hunt with tools, and we compare each other to a summer's day and mirror each other's joy with a smile. 

Natalie Angier is a Pulitzer Prize–winning science writer. German-born Christian Ziegler has won several international awards for nature photography.
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