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It’s a warm summer afternoon in New York City, and Bob and Mike Bryan are hitting the fuzzy covers off tennis balls, their looping forehands and backhands mirror images of one another. The identical twins are warming up for the U.S. Open on one of the trademark blue courts in the Billie Jean King National Tennis Center. Playing singles against each other, Bob hits a soft volley. Mike returns it with a hard shot at Bob’s head and calls out, “Velveeta.” Cheesy shot.

The Bryans take their customary position beside each other and face their coach David Macpherson and practice partner Georgy Chekhov. Although Bob is two inches taller and a leftie, the lanky, brown-eyed Bryans appear to be clones of one another. They glide across the court, perfectly in sync. A low ball sent down the middle does nothing to stymie them. Bob knows instinctively that Mike’s got it. Mike rifles a shot down the center.

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Practice ends and the twins walk in stride toward the stands, where they sign autographs. Chekhov, marveling at the brothers’ skill, says to me, “They just feel each other out there. It’s at the DNA level.”

That’s something that fans, tennis commentators, and competitors have been saying about the Bryans for over a decade. The Camarillo, California-born 35-year-olds have been the number one team for nine of the last 11 years. In 2012 to 2013, they won four consecutive Grand Slam Tournaments and the Olympic gold, an unprecedented feat that led to a new record, the so-called “Golden Bryan Slam.” It’s impossible not to ask: Do these guys posses some sort of Twin ESP?

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The short answer, alas, is no. The long answer is, well, sort of. Over the past four decades psychologists, linguists, and neuroscientists have developed a better understanding of the ways that twins like the Bryans communicate with each other. They have come up with the term “cryptophasia” to describe a secret language that twins share as kids. While scientists question whether cryptophasia constitutes a discrete language, they agree it offers a provocative look into the birth and development of language itself. Who knows? It might even offer a key into the secret of the best doubles players in tennis history.

Like most identical twins, Mike and Bob played in their own world from the time they were toddlers. Only in their case, their world was tennis. “They started playing right in the crib,” their father Wayne says. He and the Bryans’ mother Kathy, who co-owned a tennis club in the 1980s and ’90s, put balls and racquets in their crib and had them hitting helium balloons across the living room sofa as soon as they could walk. “There were gradual undulations along the way, but their progress was pretty darn identical,” Wayne says. At age 6, they won a tournament for 10-year-olds, and pretty much every kid tournament in California and the nation after that, trading the number one spot whenever they played singles.

But their personal lives didn’t blossom as smoothly as their tennis skills. When the twins were young, teachers worried about them spending too much time together. “Some doctor told my mom, ‘You gotta separate twins at a young age so they develop their own identities,’ ” Mike says. “So my mom put us in different rooms.” The Bryans sobbed so uncontrollably that their parents relented and let them sleep in the same room, often in the same bed. They stopped crying.

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They also developed a language all their own, which lasted until they were 6 years old. “They didn’t have long sentences, just little phrases, ‘mamam inim,’ that sort of thing,” says Wayne. Neither Bob nor Mike nor their father could dig exact phrases out of their memory banks. “They knew what they were saying but none of us did,” recalls Wayne.

Cryptophasia offers a provocative look into the birth and development of language itself. 

Nearly 40 percent of identical twins develop a secret language as kids. Cryptophasia comes from the Greek kryptós, meaning hidden, and phánai, to speak. It also goes by “idioglossia,” “secret language,” “Eigensprache,” “twin talk,” and “autonomous language.”

Examples are numerous. Kristy McGowan, an author and knitwear designer in Brooklyn, says she spoke a secret language with her fraternal twin sister, tidbits of which their father was able to record. “We had full conversations,” she says. “Even today, my sister will send me a picture of her dog, napping on his back, feet in the air, and the subject will be ‘illet.’ Illet means the end, no more, there’s no coming back.”

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The most famous example of cryptophasia is identical twins Ginny and Grace Kennedy from California. A documentary and many articles, including two 1970s features in Time magazine, captured the private lingo of the twins who called each other Poto and Cabengo:

         “Pinit, putahtraletungay” (Finish, potato salad hungry)

         “Nis, Poto?” (This, Poto?)

         “Liba Cabingoat, it” (Dear Cabengo, eat)

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         “la moa, Poto?” (Here more, Poto?)

         “Ya” (Yeah)

“What you find is that the words are approximations of adult language,” says Peter Bakker, professor of linguistics at Aarhus University in Denmark, author of what remains the deepest and widest study of cryptophasia, “Autonomous Languages,” published in Italian twins research journal Acta geneticae medicae et gemellologiae in 1987.

The morphology of cryptophasia appears to be straightforward, no matter whether the twins live in Russia, Germany, or Britain. “In none of the languages can any marking of tense-mood-aspect auxiliaries or verb particles be found,” he writes. In other words, “endings are always dropped,” Bakker says. “Goes becomes go, for example.”

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The sentence level offers perhaps the most unique deviation. “What happens in these languages is that the syntax is completely unlike the parents,” says Bakker. Nothing is fixed. Nouns can precede verbs and vice versa according to no set rules. If there’s a pattern, it’s only that the most important or salient elements in a sentence often come first. “Olol, mama haja wausch olo hapn,” goes an example of cryptophasia from Germany. It transliterates to “Rudi, Mommy good meat Rudi food,” meaning Rudi, mommy wants to give you good meat to eat.

Cryptophasia arises in twins of normal intelligence and generally starts if a pre-formed model language such as English is largely absent, either because of parental neglect or simply because the twins spend so much time together. Between 1 year and 18 months, when children would typically learn a native language, the twins learn from each other instead. One twin makes a mistake, the other repeats it, and the standardization or so-called fossilization of these mistakes hurries along because both children are at the same stage in their language development and are equally eager and prepared to embrace the mistakes. Some words might be onomatopoeic. Others might be purely invented. The majority are perturbations of the ambient language, like the English the twins might hear when their parents are around. Eventually these misinterpretations stop being mistakes and become a common element of twins’ grammar and vocabulary.

“Other teams have unique terminology,” says David Macpherson, the Bryans’ coach. “But they have another language.”

Some language scholars have wondered whether cryptophasia offers a window into the birth of language. Because identical twins share the same genes, cocooned in their own world, cryptophasia cracks open the long-running debate over whether human language springs from innate neurological mechanisms or is shaped by the environment in a more tabula rasa brain.

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Unfortunately, linguists haven’t made a ton of progress. “No one knows to what extent, if at all, the development of individual children’s linguistic abilities recapitulates the evolution of language in the human race,” writes linguist Guy Deutscher in The Unfolding of Language. Bakker is willing to dream a little. Cryptophasia “may shed light on the origin of language in that the words are quite crude,” he says. “Maybe when language developed it had some structure like this.”

James R. Hurford, an emeritus professor of general linguistics at the University of Edinburgh, and author of The Origins of Grammar: Language in the Light of Evolution, says he is intrigued by cryptophasia. “The best kind of evidence for what early language might have been like is where the kids depart from the adult model,” he says. Cryptophasia, with its “short sentences, probably with typically just one noun phrase, no inflectional affixes, and simplified syllable structure,” could represent words that “come naturally to humans in situations where they have to make up the code for themselves, without inheriting it culturally from a previous generation.”

Jennifer Ganger, professor of psychology and head of the Twin Lab at the University of Pittsburgh, worked for nearly a decade on a study of twins that wasn’t directly about cryptophasia, but did try to determine the heritability of language skills. She compared fraternal and identical twins, looking for similarities and differences between when they created words, and when they put words together in combination, asking parents to keep a daily log. Her take-away was the environment was more important in determining when twins learned their first words, and genetics were more important in determining how and when twins linked those words according to a coherent grammar. “Even though I do think there’s this innate grammar system that we depend on and are born with, we need other people to develop it,” she says.

In that way, cryptophasia provides a glimpse at the evolution of language. Its rudimentary words give way to a wider language shaped by the world outside. It’s a pattern reflected in cryptophasic twins themselves. In most cases, their private language begins to disappear when the twins enter school, interact with other kids, and immerse themselves in the more powerful lingua franca. Such was the case with the Bryans, who fully embraced English at the urging of professionals sometime around kindergarten. “We stopped speaking our alien language when we went to speech therapy, when we learned English,” says Mike.

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While cryptophasia may vanish with childhood, the Bryans raise the intriguing possibility that it blossoms into a new alien language in adulthood. (They have yet to be studied in any place other than tennis labs.) “Other teams have unique terminology,” says Macpherson, the Bryans’ coach. “But they have another language.”

Beginning in their teen years, Mike and Bob minted their own words for various shots and strategies. They offer a select glossary:

          “Chuckie”: serve the deuce court, poach the return of serve.

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          “Nestie”: hit a high-bouncing serve out wide, guard the double’s alley.

          “Linnie”: hit the return down the line.

          “Burgie”: slice the serve wide.

“Most teams strategize between points and are talking for sometimes up to 25 seconds,” Mike says. “That breaks up our flow.” To keep their rhythm, “We use code words. We’ve played so many matches together that we say one word and it speaks volumes.”

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In the competitive world of sports, having a shared language bestowed by common genes, certainly has advantages. It grants twins the ability to read each other’s non-verbal signals and act on them. “Coordinated performances is a phenomenon that we see unmistakably in twins,” says Nancy Segal, professor of psychology at Cal State Fullerton and author of Entwined Lives and Born Together, Reared Apart. You can see the mind-meld in twin boxers like Oscar and Javier Molina sparring against each other, twin sprinters like Jonathan and Kevin Borlée racing each other, twin skiers like the Mahre brothers bashing gates side by side. Segal recalls one pair of twins, professional basketball players Brook and Robin Lopez,1 feeling that they always just had a sense of what would come next. Similarly, Bob and Mike say they instantly know where the other will hit even before he hits, based on his strategy, his body language, even his mood.

“Doubles is all about movement,” Mike says. “It’s like you have a rope around your waist. You’re always plugging holes. If Bob’s nervous, I know what to say to him, when I should be positive, or not say anything at all. What gives us an advantage over most teams is having that kind of unspoken communication.”

Bob adds, “One of the reasons that doubles takes so long to master is because it’s such a complex sport. Because we’re twins, and we’ve been around each other so much, we don’t have to work on those sort of intangibles. We have our unspoken language. In some teams, you can see a clear-cut leader. With us, we play the best as equals, when we’re not telling each other what to do, when we’re not speaking too much, when we’re using our twin telepathy of sorts.”

Having a genetic advantage, however, is sometimes no match for Mother Nature, or, as Bob says, “Mother Tennis.” In August, after winning four straight Grand Slam Tournaments, the Bryans lost in the semi-finals at the U.S. Open. The twins, though, with an overwhelming won-loss record in 2013, will finish the year ranked number one, their fifth consecutive season at the top of the doubles tennis world.

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Eric Hansen is a contributing editor at Outside magazine. His feature about searching for the rare Himalayan fungus Cordyceps sinensis won the Lowell Thomas Award for Best Foreign Travel Article of 2012.

Photo by Adrian Dennis/AFP/Getty Images

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