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Chimps Recognize Butts the Way Humans Recognize Faces

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Recognizing a fellow human’s face is about more than just identifying a nose or mouth. It’s believed we use something called configural recognition to process the entire facial structure altogether, which is why there’s often a little bit of a lag time when we see a face upside-down (humans have an easier time recognizing other objects, like cars or houses, that have been flipped).

Researchers now believe chimpanzees have something similar to configural recognition. Only they use it to recognize each other’s butts.

In a paper published in the journal PLOS One, researchers from the Netherlands and Japan observed chimps as they examined photographs of primate buttocks and played a variation on the “match” game, coupling two identical butts together on a touch screen. They appeared slower to recognize posteriors when the images were rotated 180 degrees, indicating they rely on the same configural clues humans do. The researchers also carried out experiments on humans, who (as expected) took a longer time to process images of human faces flipped upside-down, but whose reaction time didn't change significantly when they were presented with upside-down images of human behinds.

It’s believed chimps have evolved to focus on butts due to their proximity to them while moving in groups. Walking on four legs, they’re often (literally) faced with a rump ahead of them. Since ovulating females usually have red, swollen rear ends, male chimps benefit from being able to identify them. What’s more, chimps can typically separate an ovulating non-relative from a relative, preventing inbreeding.

The paper concludes, "The findings suggest an evolutionary shift in socio-sexual signalling function from behinds to faces, two hairless, symmetrical and attractive body parts, which might have attuned the human brain to process faces, and the human face to become more behind-like."

[h/t Discover]

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Animals
Where Do Birds Get Their Songs?
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Birds display some of the most impressive vocal abilities in the animal kingdom. They can be heard across great distances, mimic human speech, and even sing using distinct dialects and syntax. The most complex songs take some practice to learn, but as TED-Ed explains, the urge to sing is woven into songbirds' DNA.

Like humans, baby birds learn to communicate from their parents. Adult zebra finches will even speak in the equivalent of "baby talk" when teaching chicks their songs. After hearing the same expressions repeated so many times and trying them out firsthand, the offspring are able to use the same songs as adults.

But nurture isn't the only factor driving this behavior. Even when they grow up without any parents teaching them how to vocalize, birds will start singing on their own. These innate songs are less refined than the ones that are taught, but when they're passed down through multiple generations and shaped over time, they start to sound similar to the learned songs sung by other members of their species.

This suggests that the drive to sing as well as the specific structures of the songs themselves have been ingrained in the animals' genetic code by evolution. You can watch the full story from TED-Ed below, then head over here for a sample of the diverse songs produced by birds.

[h/t TED-Ed]

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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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