Anyone who has been near a crying baby knows the sound drowns out virtually everything else – and for good reason. Babies typically cry for a reason, whether they’re hungry, tired, hurt or simply in need of some companionship, there are not many infants who whine for nothing.
While this is an efficient way to alert nearby humans of a baby in need, the cries can also trigger a disturbing response to creatures well outside of the human species.
Researchers recently discovered one haunting predatory response was especially triggered by infant hominid cries.
According to a paper published via Royal Society Publishing in “Proceedings of the Royal Society B: Biological Sciences” on Wednesday, these cries elicit a driving response in Nile crocodiles.
Playing “distress vocalizations” of babies belonging to several different hominid species, including bonobos, chimpanzees and humans, researchers noticed that the noises didn’t just attract the vicious reptiles but even determined the intensity of their predatory response.
Disturbingly, several factors were found to influence how aggressive these reptiles act.
Features of the recorded cries (Settle down, PETA – no bonobos were harmed in this experiment) including “harmonicity and spectral prominences” played a major part in determining the crocodile behavior.
Researchers found a disturbing link indicating that crocodiles are sensitive to the overall “distress” present in infants’ cries.
“They just react, more because it triggered some probably innate response,” University of Copenhagen behavioral ecologist Elodie F. Briefer told Smithsonian Magazine.
Briefer added: “That might be a predatory response to a prey in distress, or it could be because the sound resembles a bit what their own offspring are doing.”
If an infant is crying and a 16-foot crocodile is approaching however, don’t assume the cold-blooded killer wants to help babysit. These are ruthlessly efficient killers with a firm hold in their ecological niche.
The published study recorded predatory behavior in many of the crocodiles hearing infant cries. Many of the reptiles approached speakers playing the noises silently, as if poised to ambush. Some even attacked the speakers.
Interestingly, the crocodiles were apparently able to more accurately determine the level of distress in bonobo infant cries than humans were.
This detail underscores the reptile’s place as the undisputed apex predator in murky waterways.
According to the International Union for Conservation of Nature, crocodilian species are responsible for thousands of attacks on humans, hundreds of which are fatal interactions.
Nile crocodiles in particular are responsible for a large share of these deadly attacks.
The aggressive animals’ attraction to infant cries makes perfect sense in the context of the hunters’ lifestyle. Always on the lookout for an easy meal, crocodiles are opportunistic hunters that can easily wait just below a murky river’s surface until the perfect moment to strike appears.
In the case of a highly distressed infant, it could present the predator with an opportunity for an easy and unattended meal or the chance to snap at a distracted adult hominid.
If you plan to visit anywhere within the territory of the dreaded Nile crocodile, the best course of action is to simply stay away from the water — especially if you have a young one.