A world of phonies

Animal behaviour
Last Updated : 20 September 2010, 11:00 IST
Last Updated : 20 September 2010, 11:00 IST

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One bright October morning, Fabiano Calleia, a researcher with the Federal University of Amazonas, was out in the lowland rainforest of Manaus, Brazil, tracking his usual group of eight pied tamarins as the small, dark monkeys with their dapper white shrugs grazed on the fruits of a fig tree. Suddenly the breakfast calm was shattered by the distinctive sound of a baby tamarin’s cry – a series of short, sharp whistles, like a boiling teapot doing Morse code.

A male tamarin clambered up and down the tree, vainly trying to locate the sound’s source. The calling continued. More monkeys became riled. And then Calleia saw, to his astonishment, that the cries were not coming from a tamarin pup, but rather from a margay, an ocelotlike cat with large eyes, large paws and a large appetite for monkey meat. The margay was slinking through some nearby vines, simulating simian sounds nonstop as it headed the tamarins’ way. The spotted cat leaped, a sentinel monkey screamed and the entire troop escaped unharmed. On returning to camp, Calleia related the event to Fabio Rohe, the programme manager for the Wildlife Conservation Society’s Amazon programme, who immediately thought of what the local inhabitants had told him: that margays and other jungle cats will sometimes hunt by mimicking the vocalisations of their prey.

“I said, this is comparable to monkeys using tools! Let’s write something,” Rohe recalled in an e-mail interview. “And we started writing in a few days!” The scientists published their description of the first official “field observation of margay mimicking behaviour” in the journal Neotropical Primates last year, but only now is it circulating among field researchers more widely. The report is just one of a host of recent discoveries of priceless phonies, cases of mimicry from unexpected quarters that, really, by now we should have learned to expect.

Survival strategy

Imitation can be the sincerest form of flattery, the severest form of battery or the weirdest survival strategy, and if you think there’s nothing new under the sun, you’re right, but so what: Playing copycat turns out to be nature’s perpetual novelty machine.

Scientists recently discovered that in some ant species, the queen is a consummate percussionist, equipped with a tiny, uniquely ridged organ for stridulating out royal fanfares that help keep her workers in line. Who knew that the queen was such a squeezebox? Her freeloaders sure did. The scientists also discovered parasitic butterfly larvae in the colony that use their abdominal muscles or other body parts to precisely imitate the queen’s stridulations, an act of musical piracy that induces worker ants to flutter and fuss and regurgitate food right into the parasites’ mouths.

Within-species mimicry

Baby German cockroaches of both sexes have been found to mimic the smell and feel of adult female cockroaches, the better to dupe adult males into spreading their wings and exposing the hidden pantries beneath – pools of beery maltose sugar, proteins and fats. The males synthesise the expensive secretions as a courtship gift to woo mates, but cockroach nymphs, with their unslakable sweet mandible, have evolved the chemical and textural means to vamp.

Within-species mimicry is generally rare in nature, said Coby Schal, a professor of entomology at North Carolina State University, who recently reported with his colleagues in Animal Behaviour on the gambit they dubbed jail baiting. Then again, he added, “humans have provided cockroaches with the sort of artificial ecologies that generate really unusual behaviours.” An unpredictable food supply, scant access to soil and the essential nitrogen it holds.

The most remarkable case of mimicry to come to light lately is that of the mimic octopus of Indonesia, with so many shape-shifting, shade-changing tricks at its disposal even eight sleeves cannot hold them.

A report published in the Biological Journal of the Linnean Society presents the evolutionary backstory to Thaumoctopus mimicus, a marine mollusk that was discovered and described only in the last dozen years. Like most octopuses, T mimicus can use its nervous system to instantly change colours into a perfect wallpaper blend. Unlike most other octopuses, the mimic will sometimes choose to make itself more conspicuous to potential predators, rather than less. If it must venture out to forage in dangerous open waters, it assumes a menacing disguise appropriate to context. Before swimming above the seafloor, the octopus gives a shudder, and presto, its flesh becomes boldly striped, its arms and body resolve into a leafy, spiny form: It’s a toxic lionfish.

For skating along the sea bottom, the octopus turns its skin bumpy and beige, compresses its body, pulls its limbs to its side: It’s a toxic flatfish, undulating its fins, staring you down with its top-sided eyes. “When it’s being pestered by a damselfish, it will turn one of its arms into a sea snake, with the contrasting banding pattern of a sea snake, and with the tip of the arm thickened to look like the snake’s head,” said Healy Hamilton, a biodiversity and informatics expert at the California Academy of Sciences and an author on the report.  

We like mimicry too

We humans also like our mimicry in small, imperfect doses. Psychologists are coming to appreciate the profound importance of nonconscious mimicry in making us feel loved and appreciated, or simply smoothing the edges of our everyday affairs.

Without realising it, when we’re conversing with friends, we match our tone of voice and speech rhythms to theirs, adopt similar body posture and even imitate their tics. Studies have shown that, when students are instructed to work cooperatively with somebody who engages in either repeated hair touching or foot shaking, the students soon start fiddling with their hair or waggling a foot.

Waiters who repeat their customers’ orders word for word, or who subtly mimic a customer’s body language, earn higher tips than do waiters who paraphrase the order or forgo the gestural mirroring. Rick van Baaren’s laboratory at Radboud University in the Netherlands recently determined that, in subjects who were forced to socialise with somebody who had been instructed to avoid all forms of verbal and behavioral mimicry, cortisol levels shot up, and it took repeated normal, mimetic exchanges to bring their stress hormones back down.“I think the negative effect of not being imitated is even stronger than the positive effect of being imitated,” said van Baaren. That is, unless you’re a margay trying to make a monkey out of me.

Published 20 September 2010, 11:00 IST

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