Rattlesnake Rattles Use Acoustic Trick To Fool Human Ears

Rattlesnake Rattle

Rattlesnakes increase their rattling rate as potential threats approach, and this abrupt switch to a high-frequency mode makes listeners, including humans, think they’re closer than they actually are, researchers report August 19th in the journal Current Biology.

“Our data show that the acoustic display of rattlesnakes, which has been interpreted for decades as a simple acoustic warning signal about the presence of the snake, is in fact a far more intricate interspecies communication signal,” says senior author Boris Chagnaud at Karl-Franzens-University Graz. “The sudden switch to the high-frequency mode acts as a smart signal fooling the listener about its actual distance to the sound source. The misinterpretation of distance by the listener thereby creates a distance safety margin.”

Rattlesnakes vigorously shake their tails to warn other animals of their presence. Past studies have shown that rattling varies in frequency, but little is known about the behavioral relevance of this phenomenon or what message it sends to listeners. A clue to this mystery came during a visit to an animal facility, where Chagnaud noticed that rattling increased in frequency when he approached rattlesnakes but decreased when he walked away.

Western Diamondback Rattlesnake

This photo shows a Western diamondback rattlesnake ready to rattle. Credit: Tobias Kohl

Based on this simple observation, Chagnaud and his team conducted experiments in which objects appeared to move toward rattlesnakes. One object they used was a human-like torso, and another was a looming black disk that seemed to move closer by increasing in size. As the potential threats approached, the rattling rate increased to approximately 40 Hz and then abruptly switched to an even higher frequency range, between 60 and 100 Hz.

Additional results showed that rattlesnakes adapt their rattling rate in response to the approach velocity of an object rather than its size. “In real life, rattlesnakes make use of additional vibrational and infrared signals to detect approaching mammals, so we would expect the rattling responses to be even more robust,” Chagnaud says.

To test how this change in rattling rate is perceived by others, the researchers designed a virtual reality environment in which 11 participants were moved through a grassland toward a hidden snake. Its rattling rate increased as the humans approached and suddenly jumped to 70 Hz at a virtual distance of 4 meters. The listeners were asked to indicate when the sound source appeared to be 1 meter away. The sudden increase in rattling frequency caused the participants to underestimate their distance to the virtual snake.

“Snakes do not just rattle to advertise their presence, but they evolved an innovative solution: a sonic distance warning device similar to the one included in cars while driving backwards,” Chagnaud says. “Evolution is a random process, and what we might interpret from today’s perspective as elegant design is in fact the outcome of thousands of trials of snakes encountering large mammals. The snake rattling co-evolved with mammalian auditory perception by trial and error, leaving those snakes that were best able to avoid being stepped on.”

Reference: “Frequency modulation of rattlesnake acoustic display affects acoustic distance perception in humans” by Michael Forsthofer, Michael Schutte, Harald Luksch, Tobias Kohl, Lutz Wiegrebe and Boris P. Chagnaud, 19 August 2021, Current Biology.
DOI: 10.1016/j.cub.2021.07.018

Funding was provided from the Munich Center for Neurosciences.

19 Comments on "Rattlesnake Rattles Use Acoustic Trick To Fool Human Ears"

  1. “The snake rattling co-evolved with mammalian auditory perception by trial and error….what an idiot!

  2. Not 100% convinced this phenom is an evolutionary change.
    I noticed the change in frequencies as a kid. It was obvious to me the modulations were common with some rattlers. I always described it as a sort of ‘doppler effect’. Akin to the European-style police car sirens.
    In any case, it’s very cool… and if you understand how it works, it can save your butt!

  3. Problem is there are a lot of Rattlesnakes that will let you walk right on top of them and NEVER rattle. Those are the ones I kill.

  4. Babu G. Ranganathan | August 20, 2021 at 7:59 am | Reply

    (B.A. Bible/Biology)*

    OUR LIVING WORLD: NOT INVENTED BY NATURE

    JUST BECAUSE something exists in nature does not mean it was invented by nature. If all the chemicals (i.e. amino acids, nucleic acids, etc.) necessary to make a cell were left to themselves, “Mother Nature” would have no ability to organize them into a cell. It requires an already existing cell to bring about another cell. The cell exists and reproduces in nature but nature didn’t invent or design it! Nature didn’t originate the cell or any form of life. An intelligent power outside of nature had to be responsible.

    Miller, in his famous experiment in 1953, showed that amino acids (the building blocks of life) could form by chance. But, it’s not enough just to have amino acids. The various amino acids that make-up life must link together in a precise sequence, just like the letters in a sentence, to form functioning protein molecules. It has never been shown that various amino acids can bind together into a sequence by chance to form protein molecules.

    Natural laws may explain how an airplane or cell works, but it’s not rational to believe that undirected natural laws can bring about an airplane or a cell.

    ONCE YOU HAVE a complete and living cell then the genetic program (or code) and biological machinery exist to direct the formation of more cells, but how could the cell have originated naturally when no directing code and mechanisms existed in nature?

    Mathematicians have said any event in the universe with odds of 10 to 50th power or greater is impossible! The probability of just an average size protein molecule arising by chance is 10 to the 65th power. Even the simplest cell is made up of many millions of various protein molecules along with and DNA/RNA..

    The late great British scientist Sir Frederick Hoyle calculated that the odds of even the simplest cell coming into existence by chance is 10 to the 40,000th power! How large is this? Consider that the total number of atoms in our universe is 10 to the 82nd power.

    The cell didn’t evolve. A partially evolved cell would quickly disintegrate, not wait millions of years to become complete and living.

    WHAT ABOUT EVOLUTION? Only evolution within “kinds” is genetically possible (i.e. varieties of dogs, cats, horses, cows, etc.), but not evolution across “kinds” (i.e. from sea sponge to human). How could species have survived if their vital tissues, organs, reproductive systems were still evolving? Survival of the fittest would actually have prevented such evolution! Only limited evolution, variations of already existing genes and traits, is possible. Nature is mindless and has no ability to design and program entirely new genes for entirely new traits.

    WHAT ABOUT NEW SPECIES: Although new species have come into existence, they don’t carry any new genes. They’ve become new species only because they can’t be crossed back with the original parent stock for various biological reasons. A biological “kind” allows for new species but not new genes. Nature has no ability to invent new genes for new traits. Only limited variations and adaptations are possible in nature, and all strictly within a biological “kind” (i.e. varieties of dogs, cats, etc.).

    All species of plants and animals in the fossil record are found complete, fully formed, and fully functional. This is powerful evidence that all species came into existence as complete and fully formed from the beginning. This is only possible by creation.

    What about natural selection? Natural selection doesn’t produce biological traits or variations. It can only “select” from biological variations that are possible and which have survival value. That’s why it’s called natural “selection.” The real issue is what biological variations are possible, not natural selection. Only variations and mutations of already existing genes or traits are possible.

    Dr. Randy J. Guliuzza’s extensive research points to a better explanation than natural selection for variation and adaptation in nature. Dr. Guliuzza explains that species have pre-engineered mechanisms that enable organisms to continuously track and respond to environmental changes with system elements that correspond to human-designed tracking systems. This model is called CET (continuous environmental tracking). His research strongly indicates that living things have been pre-engineered to produce the right adaptations and changes required to live in changing environments. It’s much like a car that’s been pre-engineered so that the head lights turn on automatically when day changes to night.

    Modern evolutionists believe and hope that over, supposedly, millions of years, random mutations in the genetic code caused by environmental radiation will generate entirely new genes for natural selection to use. This is total blind and irrational faith on the part of evolutionists. It’s much like believing that randomly changing the sequence of letters in a romance novel, over millions of years, will turn it into a book on astronomy! That’s the kind of blind faith macro-evolutionists have.

    Mutations are accidents in the genetic, are mostly harmful, and have no capability of producing greater complexity in the code. Even if a good accident occurred, for every good one there would be hundreds of harmful ones with the net result, over time, being harmful, even lethal, to the species. Even if a single mutation is not immediately harmful, the accumulation of mutations over time will be harmful. At best, mutations only produce further variations within a natural species. Most biological variations are not due to mutations but from new combinations of already existing genes.

    What about genetic and biological similarities between species? Genetic information, like other forms of information, cannot happen by chance, so it is more logical to believe that genetic and biological similarities between all forms of life are due to a common Designer who designed similar functions for similar purposes. It doesn’t mean all forms of life are biologically related! Only genetic similarities within a natural species proves relationship because it’s only within a natural species that members can interbreed and reproduce.

    The actual similarity between ape and human DNA is between 70-87% not 99.8% as commonly believed. The original research stating 99.8% similarity was based on ignoring contradicting evidence. Only a certain segment of DNA between apes and humans was compared, not the entire DNA genome.

    All the fossils that have been used to support human evolution have been found to be either hoaxes, non-human, or human, but not non-human and human (i.e. Neanderthal Man was discovered later to be fully human).

    There has never been unanimous agreement among evolutionary scientists on ANY fossil evidence that has been used to support human evolution over the Many years, Including LUCY.

    Also, so-called “Junk DNA” isn’t junk. Although these “non-coding” segments of DNA don’t code for proteins, they have recently been found to be vital in regulating gene expression (i.e. when, where, and how genes are expressed, so they’re not “junk”).

    Read the author’s Internet article, NO MEAT-EATING ANIMALS EXISTED IN THE BEGINNING

    Visit my latest Internet site: THE SCIENCE SUPPORTING CREATION (This site answers many arguments, both old and new, that have been used by evolutionists to support their theory)

    Author of popular Internet article, TRADITIONAL DOCTRINE OF HELL EVOLVED FROM GREEK ROOTS

    * I have had the privilege of being recognized in the 24th edition of Marquis “Who’s Who In The East” for my writings on religion and science, and I have given successful lectures (with question and answer time afterwards) defending creation from science before evolutionist science faculty and students at various colleges and universities.

    • Clyde Spencer | August 22, 2021 at 5:17 pm | Reply

      A lot of nebulous claims without any citations! You apparently believe it. However, just saying something is so is rarely convincing for those who think.

  5. Babu G. Ranganathan | August 20, 2021 at 8:00 am | Reply

    (B.A. Bible/Biology)*

    THE BIBLE TEACHES THAT SNAKES ONCE HAD LEGS

    The Bible teaches in Genesis 3:14 that the serpent (snake) was a member of the cattle family before it was cursed and made to crawl in the ground. So, the Bible implies that snakes, indeed, once had legs.

    Read my popular Internet articles:

    NATURAL LIMITS OF EVOLUTION
    HOW DID MY DNA MAKE ME?
    HOW FORENSIC SCIENCE REFUTES ATHEISM

    Visit my newest Internet site: THE SCIENCE SUPPORTING CREATION

    Author of popular Internet article, TRADITIONAL DOCTRINE OF HELL EVOLVED FROM GREEK ROOTS

    * I have had the privilege of being recognized in the 24th edition of Marquis “Who’s Who In The East” for my writings on religion and science, and I have given successful lectures (with question and answer time afterwards) defending creation from science before evolutionist science faculty and students at various colleges and universities.

  6. Is there any way to remove fake news (bible crap) from a science article?
    People dont want to read this ancient “mis-understanding” of the world.

  7. This is the great error of our time; some scientist receiving funding for such nonsense. Could it be the more tense the snake gets before it strikes the faster the rattle wiggles. Who really cares. They furthered no science; and wasted money that could have gone elsewhere to help the world. Remands me of the study about growing marigolds out of moon dust.

  8. Rattlesnake Jake.

  9. Wow babu, you sure do like to hear yourself talk.
    Maybe you should learn to listen more and talk less.

  10. Religious scam | August 20, 2021 at 1:18 pm | Reply

    Religion again!!!! Shut up and Just read your damn bible.

  11. Oh,ye of little faith.. so trusting of man’s ‘opinions’ regarding the beginning of life.. all they truely know is what they dont believe.

  12. Hmmmmm, to “Read a book”,
    Read a book said “Is there any way to remove fake news (bible crap) from a science article?
    People dont want to read this ancient “mis-understanding” of the world.”
    So, this is the perfect comeback for a scientific fact denier. I bet you’re still believing the covid story and wearing your mask. Your science is only the facts that fit your predisposed Prejudice is the opposite of scientific. Please, read more than one book and learn the process.

  13. Babu has a little time on his hands. Possibly some physical activity couldn’t hurt him.

  14. This has been well known to red necks for decades.
    -Dr. Redneck.

  15. Clyde Spencer | August 22, 2021 at 5:24 pm | Reply

    Rather than being a “trick,” the snake is probably making a very direct statement: “You ignored my initial warning and kept coming. I’m getting very annoyed and definitely will bite your a$$ if you continue to approach me! Back off!”

    The Bible Thumper is off topic.

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