The sounds of alarming sirens are very similar to a wolf howl. Czech and German researchers came to this conclusion, comparing the voices of these animals with the alarm signals that are used in the Czech Republic, Afghanistan, and the United States. As noted in an article for Acta Biotheoretica, this similarity is hardly realizable. Most likely, the creators of sirens tried to solve the same problem that wolves faced in the course of evolution: to create a recognizable signal that will be heard from afar. And the fear that people feel before the wolf howl further increases the effectiveness of sirens.
Over millions of years of evolution, human ancestors have acquired a special sensitivity to signals that may indicate a threat to health and life. Thanks to her, people are still afraid of snake hiss and aversion to the smell of rot. Reactions to some stimuli are so deeply ingrained that humans have found new uses for them: just remember the yellow-black warning signs that go back to the coloration of wasps and bees.
A team led by Lucie Němcová of the Czech Agricultural University has suggested that another popular warning signal may have ancient evolutionary roots. We are talking about sirens, which were first used in the middle of the 19th century, and became widespread in the middle of the 20th century.
According to the idea of the researchers, the sounds of sirens seem especially disturbing to people, since they resemble the howl of ordinary wolves ( Canis lupus ). Although today the number of wolves in most of the range has decreased and they rarely pose a real danger to humans, the inhabitants of Eurasia and North America have long coexisted with these large predators and are used to perceiving them as a threat.
To test their hypothesis, the researchers assembled a database of 104 records of a wolf howling. Having selected 59 of the highest quality ones, the authors compared them with the sounds of alarm sirens used in the Czech Republic, the USA, and Afghanistan, as well as the signals emitted by Czech ambulances.
Comparison of the spectrograms showed that on most segments the frequency of the wolf howl and the sounds of various sirens are almost the same. According to the authors, the similarities are too great to be accidental. However, the creators of warning systems hardly deliberately tried to copy the voices of predators. Rather, there has been a convergence between living organisms and technology.
Trying to create a recognizable signal that can be transmitted over long distances, engineers came up with a solution that evolution had worked out long before them. And the tendency of people to regard wolf howls as a signal of danger further increased the effectiveness of sirens. Interestingly, wolves also seem to perceive the similarity of these signals with the voices of their relatives: it is often reported that the sound of a siren can provoke a wolf (as well as dog) howl in response.
In conclusion, the authors suggest paying attention to other sounds made by dangerous animals, for example, the hissing of snakes or the buzzing of hornets. Perhaps they can also be used to create effective warning signals.