All Human Languages Mysteriously Obey Zipf’s Law Of Abbreviation. It Applies To Bird Songs Too.

What is Zipf’s law of abbreviation?

Developed by American linguist George Kingsley Zipf in the 1930s, Zipf’s law of abbreviation states that the more frequently a word is used, the shorter that word tends to be, and vice versa. 

Rarely used words tend to be long, while frequently used words are short. For instance, the most common words in English are: the, be, to, of, and, a; all of which are very short. Some of the longest words – let’s say pneumonoultramicroscopicsilicovolcanoconiosis or antidisestablishmentarianism – don’t generally come up in conversation that often (unless you’re very odd). 

When long words do show up often, we tend to shorten them. Television becomes TV, refrigerator becomes fridge, and influenza becomes flu. 

This doesn’t just apply to the English language. Linguists have demonstrated that Zipf’s law of abbreviation also exists in Chinese, Croatian, Czech, Dutch, English, French, German, Greek, Hungarian, Indonesian, Italian, Polish, Portuguese, Romanian, Russian, Slovenian, Slovak, Spanish, Sundanese, Swedish, and more. 

Do birds also follow Zipf’s law of abbreviation?

Now, biologists at the University of Manchester in the UK and Chester Zoo have found evidence that birds also appear to follow Zipf’s law of abbreviation: the most frequently used chirps and tweets tend to be shorter, and vice versa. 

“We know that birds and humans share similarities in the genes and brain structures involved in learning to communicate but this is the first time we’ve been able to detect a consistent pattern of ZLA [Zipf’s law of abbreviation] across multiple bird species,” Dr Tucker Gilman, lead author and Senior Lecturer at The University of Manchester, said in a statement.

The team used a new open-source computational tool called ZLAvian that analyzes bird songs, focusing on how the length of a note relates to how often each bird uses it. This statistical tool measures how strongly note lengths and note frequencies match for each bird, then combines those results across all birds to produce a population-level score.

In total, they analysed more than 600 songs from 11 bird populations across seven different species. While individual populations didn’t always show clear signs of Zipf’s law of abbreviation, a stronger pattern emerged when the data was combined, showing more frequently used birdsong phrases were significantly shorter.

“Studying ZLA in birdsong is far more complex than in human language. Birds often have very few note types, individuals even within the same species can vary widely in their repertoires, and classifying notes is tricky too,” added co-author Dr Rebecca Lewis, Conservation Scientist at Chester Zoo.

“Our research has taught that it’s important to look across a wide range of species when looking for language patterns and we hope ZLAvian will make it easier for other researchers to explore these patterns in more birds but also other animals in the future.”

Scientists believe that many different animals follow this linguistic rule. It’s been documented in the songs of humpback whales, as well as the vocalizations of African penguins.

Zipf’s law reveals fascinating things

Ultimately, Zipf’s law of abbreviation allows communication to become more efficient. It’s very similar to the “principle of least effort”, the idea that systems will naturally develop to choose the path that requires the least amount of energy to achieve a goal. Its presence in non-human animals highlights that it’s not a conscious choice or a quirk of human culture, but a fundamental rule shaping how many systems work.

Zipf’s work went even deeper and got more mysterious. He also found that the most frequently used word in a language – in English, “the” – appears about twice as often as the second most common word, three times as often as the third, four times as often as the fourth, and so on. This separate but related pattern is known simply as Zipf’s law (as opposed to Zipf’s law of abbreviation), and it shows that languages are shaped not only by brevity, but also by a surprisingly consistent mathematical order.

The new study is published in the journal PLOS Computational Biology.