Crocodiles Are Alarmingly Attuned To the Cries of Human Infants (science.org) 53
sciencehabit shares a report from Science: Whether they're in mortal peril or just suffering from indigestion, infants across the animal kingdom cry out to tell their parents they need help. Unfortunately for them, the parents aren't the only ones attuned to the cries of their vulnerable young. Nile crocodiles are uniquely sensitive to the wails of distressed primate babies, according to a new study -- and the more anxious the cry, the more interested the crocs become. Indeed, according to the research, published today in Proceedings of the Royal Society B: Biological Sciences, the reptiles are even better at identifying the emotional cues hidden in the wails of babies than we are -- perhaps because they've evolved to home in on helpless prey.
To make the gruesome find, Nicolas Grimault, a bioacoustician at the University of Lyon, and colleagues visited a zoo in Agadir, Morocco, that houses more than 300 Nile crocodiles (Crocodylus niloticus) -- a predator particularly well suited to hunting primates and other mammals. The researchers set up loudspeakers alongside four ponds, where, at each, as many as 25 crocodiles sunbathed on red rock ledges. The speakers blared out a series of cries from chimpanzee (Pan troglodytes), bonobo (P. paniscus), and human infants, captured in a variety of situations in order to document a wide range of emotion. The human infants, for example, were recorded both during bath time and vaccination. (You can listen to the sounds yourself in the videos [here].) Many of the crocs, male and female, responded to the cries by seeking out the source of the sound, rapidly approaching the loudspeaker and sometimes even biting it. But their response depended on the characteristics of the cries they heard: Crocs were more likely to respond to recordings with acoustic features known to correlate to highly upset infants such as disharmony, noise bursts, and uneven tones reminiscent of radio static.
The reptiles seemed to be identifying the most distressed prey on the basis of their cries, Grimault says -- a smart strategy for an animal that is a highly opportunistic hunter. "A baby might not scream at the top of its lungs if it's with its mother," Reber adds, "but it might ... if it fell into the water." On average, about one in five crocodiles responded to recordings of human infants experiencing low levels of distress, whereas about one-third responded to the cries of severely distressed human babies. Surprisingly, the crocodiles seemed even better at detecting distress in the cries than humans were. When the researchers asked human volunteers, all of whom had experience with human infants, to listen to the same recorded cries and estimate the level of distress communicated by the sounds, the participants used different features than the crocs did to evaluate the sounds, basing their decisions largely on the pitch of the cries. The researchers note that it's possible some of the crocodiles were acting out of parental concern, rather than blood lust. "Nile crocodile mothers respond to distress calls from their own young, and their attempts to bite the loudspeaker might not be as bad as they look -- mother crocodiles are known to gingerly pick up their own babies in their jaws."
To make the gruesome find, Nicolas Grimault, a bioacoustician at the University of Lyon, and colleagues visited a zoo in Agadir, Morocco, that houses more than 300 Nile crocodiles (Crocodylus niloticus) -- a predator particularly well suited to hunting primates and other mammals. The researchers set up loudspeakers alongside four ponds, where, at each, as many as 25 crocodiles sunbathed on red rock ledges. The speakers blared out a series of cries from chimpanzee (Pan troglodytes), bonobo (P. paniscus), and human infants, captured in a variety of situations in order to document a wide range of emotion. The human infants, for example, were recorded both during bath time and vaccination. (You can listen to the sounds yourself in the videos [here].) Many of the crocs, male and female, responded to the cries by seeking out the source of the sound, rapidly approaching the loudspeaker and sometimes even biting it. But their response depended on the characteristics of the cries they heard: Crocs were more likely to respond to recordings with acoustic features known to correlate to highly upset infants such as disharmony, noise bursts, and uneven tones reminiscent of radio static.
The reptiles seemed to be identifying the most distressed prey on the basis of their cries, Grimault says -- a smart strategy for an animal that is a highly opportunistic hunter. "A baby might not scream at the top of its lungs if it's with its mother," Reber adds, "but it might ... if it fell into the water." On average, about one in five crocodiles responded to recordings of human infants experiencing low levels of distress, whereas about one-third responded to the cries of severely distressed human babies. Surprisingly, the crocodiles seemed even better at detecting distress in the cries than humans were. When the researchers asked human volunteers, all of whom had experience with human infants, to listen to the same recorded cries and estimate the level of distress communicated by the sounds, the participants used different features than the crocs did to evaluate the sounds, basing their decisions largely on the pitch of the cries. The researchers note that it's possible some of the crocodiles were acting out of parental concern, rather than blood lust. "Nile crocodile mothers respond to distress calls from their own young, and their attempts to bite the loudspeaker might not be as bad as they look -- mother crocodiles are known to gingerly pick up their own babies in their jaws."
Re:Something might be wrong, actually (Score:5, Informative)
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Humans are primates. Not sure where you see the problem.
And that for centuries, have had contact with humans. Some cultures kept Nile Crocodiles as pets/livestock.
I'd wonder if an Australian crocodile would have a similar response, having had much less contact with humans. I think the discovery here isn't that they had a response, but the degree of response.
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Cats: Associated with Egypt, evolved around human/primate cries. Nile Crocs: Associated with Egypt, evolved around human/primate cries. I can see how domestication (maybe only proximity for the crocs) could take it in that direction.
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The Australian crocodiles have been encountering humans for over fifty thousand years. They know who's in charge [youtube.com].
Re: (Score:2, Interesting)
Sound as well as visual cues to signal child? (Score:4, Interesting)
I would note the cry difference between their babies (sort of a muffled sound, that doesn't get very high pitched... almost a grunt) and humans. I'm guessing any croc babies that didn't grunt were eaten.
For most species they need to care for their babies, and the babies need to signal... I'm guessing the process is quite conserved between creatures (same underlying genes and mechanism). I agree finding a divergence is interesting, but all it took was hearing the babies to realize that for me.
In the animal kingdom there are certain physical characteristics that signal a baby. Large eyes relative to head size, for instance. I'd assume vocal characteristics apply too. Meaning it wouldn't specifically be primate babies... Kittens yowl pretty similarly to my ears. And wolf/dog howls can be pretty high pitched.
How about... (Score:2)
A baby wailing because it just filled its diaper and needs to be changed? Would the croc get excited about that extra load of nutrients?
This seems like a bit of a stretch. Why on earth would the researcher pick the sound of a baby upset because it's getting vaccinated? That isn't exactly something the crocs could have evolved to recognize...
Re:How about... (Score:5, Insightful)
A baby wailing because it just filled its diaper and needs to be changed? Would the croc get excited about that extra load of nutrients?
Extra? Where do you think those nutrients came from...?
Why on earth would the researcher pick the sound of a baby upset because it's getting vaccinated? That isn't exactly something the crocs could have evolved to recognize...
I'd imagine that it was one of the easiest and most ethical ways of recording "injured" babies in distress.
Evolution in Action (Score:4, Insightful)
A young human is a pretty easy meal compared to almost every other animal, so maybe we're a favoured prey.
Re:Evolution in Action (Score:5, Informative)
Nile crocodiles evolved in the same place hominids did, and eventually humans, so I'm assuming they've been eating our young for all that time.
A young human is a pretty easy meal compared to almost every other animal, so maybe we're a favoured prey.
It's buried pretty deep in the article but:
Meanwhile, by focusing on universal signs of distress like staticky disharmony, the crocs consistently responded to distress across species lines.
So most baby animals have a similar crying sound and crocs are attracted to all of them.
So the croc very well could have evolved to figure out that a crying infant of any species is an easy snack. And as the researchers said it might even be that the crocs were concerned that the cry was that of a crocodile infant, which might be an easy snack regardless [wwwildnature.com].
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Nile crocodiles evolved in the same place hominids did, and eventually humans, so I'm assuming they've been eating our young for all that time.
A young human is a pretty easy meal compared to almost every other animal, so maybe we're a favoured prey.
It's buried pretty deep in the article but:
Meanwhile, by focusing on universal signs of distress like staticky disharmony, the crocs consistently responded to distress across species lines.
So most baby animals have a similar crying sound and crocs are attracted to all of them.
So the croc very well could have evolved to figure out that a crying infant of any species is an easy snack. And as the researchers said it might even be that the crocs were concerned that the cry was that of a crocodile infant, which might be an easy snack regardless [wwwildnature.com].
Also, you have to consider the fact that humans only survived with such vulnerable babies because you don't want to fuck with the adults that are almost always nearby. Coming after human babies preferentially doesn't seem like it would be evolutionarily advantageous - you're more likely to end up being pureed and fed to said babies.
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Bad Evolutionary Move (Score:2)
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Good Science, not Political Ideology (Score:5, Insightful)
Re:Interesting article UNTIL... (Score:5, Insightful)
"and their attempts to bite the loudspeaker might not be as bad as they look"
LOL what in the f... now even the crocs have a chance in this world of "equality". Is that what "woke" is?
It's no different than all those woke white folks out there talking about those peaceful tourists on January 6th. You know, the ones who used flag poles to beat police officers [cbsnews.com], or usedother poles [thehill.com] to do the same, or who said the police should be killed [justice.gov].
You know, that kind of woke.
Cats therefore should keep their traps shut (Score:2)
when they visit croc zoos [seniorcatwellness.com].
Makes sense (Score:4, Funny)
What meat is more forbidden than human baby? It absolutely has to be delicious and the crocs know it.
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Studying animals in captivity (Score:2, Informative)
Re: Infant chumming. (Score:2)
Why refrain when you can research instead? There's no shortage of bait...
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Why refrain when you can research instead? There's no shortage of bait...
On the contrary, there's a significant shortage of bait. Haven't you heard? Birth rates have dropped below replacement rate throughout the developed world.
Surprisingly true... (Score:5, Interesting)
I used to work at a small zoo in the southeast US... We had a little picnic table area near our outdoor snack booth where people would chill out and observe the gator pit from above. Of course the area was cordoned off with those steel cables running across any open areas to prevent idiots from doing anything stupid over the rail of the deck, but they could absolutely get a good close view... and vice versa... One day this family came in and I guess fed a tiny toddler a jalapeno or something because that little kid started wailing like I'd never heard. But then I noticed half the gators had uncharacteristically swarmed underneath their specific area... The biggest one we called "bluto" had taken extreme interest and kinda spooked the family. I went over to reassure them he was well secured and said, hey, bluto, what do you WANT? Trying to make light of things... All of a sudden he looked at us straight in our eyes and said, "I need about tree fiddy."
Not an American Word (Score:2)
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>our outdoor snack booth . . . the gator pit
yeah; that's kind of the4 crux of it! :_)
hawk
It's the infants' fault (Score:1)
...for being delicious.
their attempts to bite might not be as bad (Score:2)
We've evolved strategies also... (Score:2)
Crocs have Hearts of Gold (Score:2)
it's possible some of the crocodiles were acting out of parental concern, rather than blood lust
Yeah underneath that hideous scaly exterior and behind those massive teeth they really just want to be loved as Ford suggested. But the Vogon replied, .. no .... I just write poetry to throw my mean callous heartless exterior into sharp relief..
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Pest removal potential is obvious. (Score:2)
Gator tails are tasty and gators may be taken per state rules (which vary, look up yours). Luring them out of water (if the lake for example is on your property) into convenient shooting range by playing crying infant noises would be far more convenient than other hunting methods.
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Well, sure .. (Score:1)
it's how they keep the abandoned babies rate down (Score:2)
Incomplete Study (Score:2)
They didn't compare to screams of adolescent and adult humans.
Possibly more difficult to obtain (but I guess I could help with that).
Crocodile boots, anyone? (Score:2)
That explains it (Score:2)
non-primate mammalian example (Score:1)
Oooh, we can *listen* to the sounds... (Score:1)
Oh, yes, please. The sounds of crying infants. I'm definitely going to set up a playlist that just loops those forever.