(Intro)

Hello folks! Welcome to the debunker. If you've never been here before, this is where I come to break it to you that the stuff you've been seeing on the internet for the past week isn't what you think it is. In this week, I'd like to talk to you about this fish. 

It's called a pacu, and even though it's native to South American rivers, one was recently caught in Swedes Lake, New Jersey. Now because of its rows of eerily human-like teeth, pictures of this thing are everywhere, crowding everyone's Facebook feed and Tumblr dash with arguments about whether it's real and if so, what it is. 

And I'm happy to report that what you've probably heard about the pacu is only like half-bunk? The non-bunk part is that is really what this fish looks like. Pacu are related to piranhas as South America's infamously carnivorous fish but they don't really have that much in common with them.

Piranhas have small, triangular, razor-sharp teeth whereas pacu have teeth that resemble human molars because they're mostly herbivorous and our molars are what we use to mostly grind up plant matter. But the pacu owe their bizarre teeth to their equally bizarre eating habits. In their native habitats, they are known to eat ripe fruits and nuts that fall from trees into the water. This fish eats fruits and nuts. 

Speaking of nuts though, gotta do some debunking while we're here in the debunker. Despite what you might have heard, pacu have no interest in eating human testicles. That rumour has its origins in - surprise - cable TV. In a supposed science and nature show on a network whose name rhymes with "smational smagraphic", a TV host who was fishing for pacu in Papua New Guinea was told a story by some locals about two men whose testicles were bitten off by a mysterious unidentified fish. The story was never confirmed and even so, no one knows if the culprit was a pacu, but that got translated by the internet into "Pacu fish will bite your nards off".

Now there's still the question of how a South American fish ended up in New Jersey or Papua New Guinea. Turns out the pacu was introduced in Southeast Asia as a food source but the ones found in North America and Europe probably started out as someone's pets. Pacu are popular aquarium fish, but they can grow to be longer than a meter, so often pacu owners will just throw them in a nearby lake or river when they outgrow their tanks. In either case, the pacu is now an invasive species found from Scandinavia to Southeast Asia where it can quickly out-compete local wildlife for food and territory with its big nasty teeth. 

But there's another animal that's become famous for its mouth recently, the chestnut-crowned babbler bird. According to new research published this week, these birds are the first known species, other than humans, to put meaningless sounds together to form meaning. 

Babblers are a small Australian bird that get their name from the fact that instead of singing, they string different kinds of calls together, basically they babble. And recently, and international group of ornithologists analyzed the calls of the babbler and noticed that different sounds seem to be repeated in certain ways.

The calls consisted of two main elements which the researchers named A and B. One call takes the form of AB while the other is BAB, and researchers were able to show that to other chestnut-crowned babblers, AB means flight while BAB has to do with feeding babies in the nest. 

After observing a group of birds for about 6 hours, the team noticed that about 60% if the time, the birds made the A-B call while in flight, and about 70% of the time the parents were feeding their babies, they made the B-A-B call. So apparently, when babblers take flight, they go around saying the bird equivalent of "I'm flying!", and when their feeding their offspring I guess they're saying something like "Here's dinner kids!"

The researchers tested their hypothesis that these calls were related to specific behavior by exposing a group of 16 babblers to the different calls six times. When the birds heard the flight call they started looking and hopping around like they were expecting another bird to fly by, and when they heard the B-A-B call they were looking at their nests more often. 

By analyzing the way babblers construct their language and finding other animals that do the same, researchers think that we might be able to learn something about the way human language developed. For example, whether it's more efficient to rearrange the sounds you already have instead of making up new ones. 

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