While thinking about what causes people to treat money differently, behavioural economist M. Keith Chen hit on a fascinating idea. “Why is it that countries with seemingly similar economies and institutions can display radically different savings behaviour?” he asked in a 2012 TED talk. Chen’s idea was that the languages we speak alter the way we think about the future, making us more or less inclined to behave with the future in mind.

The idea that languages can shape the mind, and therefore culture, is an idea with a long tradition. It’s still a subject of debate, with evidence supporting the idea ranging from extremely shaky to somewhat reasonable. Chen’s interest was in how different languages express ideas about the future. For example, English uses auxiliary verbs to mark future tense, like “It will rain tomorrow.” In German, the verb stays the same in both the present and future tenses: “Morgen regnet es,” translates directly to “It rains tomorrow.”

In a paper published in 2013, Chen reports that speakers of languages with no separate future tense markings showed more forward-thinking behaviour. That is, they were more inclined to save money, avoid smoking, avoid obesity, and practice safe sex than speakers of languages that have entirely different markings for future and present tense. The explanation he offers is that mentally connecting the present and future (like German speakers do) makes people more inclined to behave with the future in mind.

The relationship between language and other features can sometimes be nothing short of astonishing. A 2007 paper found that speakers of languages with more sonorous speech sounds—sounds that are louder and carry more easily, like “aaaaa” compared to “t”—also have more premarital and extramarital sex. “Could opening the mouth wide to make sonorous sounds be partially explainable as an effect of sexual permissiveness?” the authors ask.

Is this starting to sound fishy? There’s good reason to think it should. Data can often produce striking patterns because of the way different features are related to one another—but in reality, these patterns simply aren’t related in the ways suggested by the researchers who find them. The features are correlated: as extramarital sex goes up, so does sonority, but the correlation is spurious—meaningless.

Why, then, do we keep bothering with correlations?

Kick-starting science

Despite the constantly looming threat of the spurious result, correlational studies can actually be an incredibly useful technique, say Seán Roberts and James Winters, two researchers who study the evolution of human culture. They’ve embarked on a campaign to address the tricky problem of correlational research in the field, working to identify what makes a correlation robust and what methods are best to use.

One area of huge potential for correlational research is as feasibility studies, said Roberts: strong evidence of a correlation can help other researchers know where to look. Finding a correlation “isn’t necessarily proof of a theory, but it’s encouraging,” Roberts told Ars in a phone interview. “It means it’s now worth actually investing in collecting the real data, which is expensive and takes time.”

Another slightly more controversial role for correlations is hypothesis generation. Seeing patterns in data can spark a new idea that a researcher might otherwise not have thought about. Take, for instance, the unexpected pattern in genetic data that uncovered a controversial connection between genetics and language.

Tonal genes? The genes examined by Dediu and Ladd were Microcephalin and ASPM, both of which seem to be involved in brain development. Certain mutations on these genes can cause serious problems with foetal brain development, but other variations have been found to have no effect on intelligence, brain size, or schizophrenia. The genes examined by Dediu and Ladd were Microcephalin and ASPM, both of which seem to be involved in brain development. Certain mutations on these genes can cause serious problems with foetal brain development, but other variations have been found to have no effect on intelligence, brain size, or schizophrenia. An allele (variant) of the Microcephalin gene, called MCPH-D, seems to have spread throughout Asia, Europe, the Americas, Oceania, and North and East Africa since its appearance around 37,000 years ago. The ASPM allele, ASPM-D, has spread to North Africa, Europe, and Central and Western Asia since it emerged approximately 5,800 years ago. Populations that have high frequencies of both new alleles of these genes have very low frequencies of tone languages. Meanwhile, populations that have the old alleles of the genes have very high frequencies of tone languages. Populations that have the new allele of MCPH but the old allele of ASPM are somewhere in between.

In 2005, Bob Ladd came across a map in New Scientist magazine. The map showed the global distribution of people with two distinct genetic variants. That’s funny, he thought: the pattern looked familiar.

Ladd, a linguist who studies the sounds used in speech, had been thinking for a long time about tone languages. These are languages that use pitch not just for emphasis or emotion, but to distinguish between words. Mandarin Chinese, for example, uses high, low, rising, and falling tones to change the meaning of a word. Ladd was interested in why some languages have tone while others don’t.

The map in New Scientist matched the distribution of tone languages around the world. “I had been thinking about what kind of difference could involve using tone in the lexicon, and I thought, if there’s a genetic difference, then it’s about brain structure,” Ladd told us.

Dan Dediu, a PhD student in the same department, was pursuing the idea that genetic diversity could influence linguistic diversity. Most linguists would disagree with this hypothesis. All babies can learn all languages equally well, so linguistics has long argued that there’s no reason to think that different genes lead to different languages.

But, argued Dediu, there are small individual differences in people’s language ability, such as how fast they learn a second language. This variation could be caused by small genetic differences that make certain kinds of language structures easier to learn for some people than others. What if, over time, small biases in a population could accumulate, making that population more likely to speak a tone language? Dediu and Ladd decided to work together.

When they looked into the data, the relationship actually seemed to be there: populations with a particular genetic pattern were also more likely to speak a tone language. More specifically, populations with the newer variants of the two genes in question had fewer tone languages, while populations with the older variants had more. (See sidebar for more details.)

But the research was only correlational—it couldn’t prove that the genes caused the bias towards tone languages, and it wasn’t even clear exactly what difference these genes made to the brain.

Nonetheless, it was a starting point. The study provided some degree of evidence for Dediu’s hypothesis that small genetic biases could influence the form a language takes, and it provided a launching pad for future research.

Listing image by flickr user: su neko