EVERYONE KNOWS the Eskimos have dozens, if not hundreds, of words for snow because of their intimate knowledge of their environment. Except that everyone cannot “know” this, because knowledge requires a statement to be true. In fact, the Eskimo snow story is a factoid, a word coined by Norman Mailer for a fun, roughly fact-shaped object that is not, in fact, a fact—in the same way a “spheroid” is not quite a sphere.

The Eskimos (or Inuit, as most prefer to be called) don’t really have hundreds of words for snow because of their fine sense of its variety. Rather, they have a virtually infinite supply of words for everything, because of the nature of their languages. Inuit languages allow lexical roots to be strung together to make long, highly specific words, including some that might make an entire sentence in English. “Snow that has turned grey from being walked on repeatedly”, a noun phrase in English, might be a single word in Inuit. But the number of basic snow-related roots is not much larger than the number of snow words in English.

For many linguists, the Eskimo snow story has become an example of an embarrassing, exoticising fairy tale about an unfamiliar culture, passed round by those who know nothing of it. It is also the paradigmatic example of assuming a kind of mystical connection between language, land and culture—which falls apart under serious scrutiny.

Today, efforts to draw links between language and the environment are more respectful. One linguist has observed that languages with certain rare consonants (called ejectives) are more prevalent at high altitudes, perhaps because those are easier to pronounce in lower air pressure. Another team found that languages which use tones (ie, changes in pitch) in their vowels, to distinguish one word from another, are linked with humid climates. This is purportedly because humidity helps the vocal folds produce the tones. These causal relationships are not always accepted by other scholars.

Recently, though, a large study of colour words around the world has found a clear link between geography and vocabulary. Colour is a classic case of a spectrum. There is no sharp break between, say, blue and teal, and cultures divide the continuum in different ways. Some languages have just two colour-related words, for light and dark. A pair of linguists, Brent Berlin and Paul Kay, wrote in the 1960s that if they have a third, it is almost always for red; a fourth and fifth are usually for green and yellow.

Blue comes only sixth in the Berlin-Kay schema, elementary as it may seem. Besides the sky and sea, though, there are few blue things in nature, which may make the word less necessary; rarely does anyone say “look for a blue plant”, because these are uncommon. Many languages lump together blue and green, a chunk of the spectrum linguists call “grue”.

The new study breaks ground by finding that there is indeed a link between the use of grue words and the environment, specifically sunshine. Populations exposed to lots of sunlight are more likely to talk about “grue”, note Mathilde Josserand, Emma Meeussen, Asifa Majid and Dan Dediu. One possible reason is that long-term exposure to ultraviolet light can cause changes in the retina that make it more difficult to distinguish blue from green.

The researchers tested a host of other theories to account for the presence of a “grue” term, and found a weaker but still interesting link to culture, rather than physiology. They discovered that larger populations were more likely to have a distinct “blue”. Population size, they speculate, is a reasonable proxy for cultural complexity—the kind, for instance, that would lead cultures to develop dyeing techniques, and thus create artificially blue objects.

This is the first study to test so many of these hypotheses to see which hold up best. That is an admirable approach, which reduces the chances of a coincidental finding, the type that pops up all the time when researchers scour databases looking for linked variables. (One such effort found a link between acacia trees and tonal languages, a connection rather difficult to explain.)

The limitation is that the thing being tested (such as whether there is a distinct word for “blue”) must be quite simple, in order to compare widely varying languages. But the strength of this method is that it produces conclusions which, if you drop them into cocktail-party conversation, are more likely to be legitimate. Fun facts are only really so when they are, indeed, facts.