A Bar-Ilan University study conducted on the population of rock hyraxes in the Ein Gedi Nature Reserve offers new insight into sex differences and evolutionary language development.The population had been carefully monitored since 1999 as part of a study led by Prof. Eli Geffen of Tel Aviv University, as well as Dr. Amiyaal Ilany and Prof. Lee Koren of Bar-Ilan’s Mina and Everard Goodman Faculty of Life Sciences. Communication is something all social animals practice, humans included. This is essential to maintain any semblance of social structure, and groups with mates require communication to take place on a constant basis. Therefore, the more complex the social structure, the more complex the communication structure.This is further elaborated upon by the scientific principle known as the Law of Brevity. Popularized in the 1930s by George Kingsley Zipf, the Law of Brevity explains that there is a negative correlation between a word’s length and the frequency with which it is used.In other words, the shorter the word, the more it’s used.But is this principle true for animals as well as humans? Many would argue no, because animals usually need to communicate from farther distances than humans do, which often necessitates longer and louder calls.It is with this in mind that the researchers studied the rock hyrax, also known in the Bible as coney. The small mammal, most closely related to the elephant, typically lives in groups of 30, including multiple females and children with just one male. Bachelor males, by contrast, live solitary lives and are usually only social during mating season.The hypothesis was that shorter calls, not longer, would be more frequent.To test this hypothesis, the researchers fitted 19 males and females with audio recorders and recorded their communications over the course of a week, subsequently creating a repertoire of their calls.The results found shocking differences with the Law of Brevity based on sex. Females use longer calls far more often, but typically did so softly. The males, however, have far more limited communication opportunities, and as a result are shorter but louder. This difference in amplitude is due to the need to reach others from a farther distance.“This raises the question of why human language isn’t optimized by amplitude,” said Ilany.“Could it be because the development of artificial signaling means for long-range communication made high amplitude calls less needed? Perhaps the high pressure for increased informational content in the emerging human languages capped the amplitude of the vocal signals, as loud calls have less capacity for informational content. Both scenarios could lead to duration-based optimization that is now widespread,” he wondered.The study was published in the journal Evolution Letters, and shows that differing necessities in gender and life can influence using different voices for different reasons.This, the study says, can provide clues for how humans began to develop their especially complex forms of communication.