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Fascinating.

A Gunnison's prairie dog can look at a human walking through its colony and produce an alarm call that tells every other prairie dog in the town what species is approaching, how big it is, what color shirt it is wearing, and how fast it is moving. The call lasts less than a second.

Con Slobodchikoff spent over thirty years decoding that call. He is a professor emeritus at Northern Arizona University in Flagstaff, and his research colonies sat just outside the doors of the campus. He started in the 1980s by recording alarm calls and noticed that prairie dogs did not produce the same sound for every threat. A hawk triggered a different call than a coyote. A coyote triggered a different call than a dog. A dog triggered a different call than a human. The calls were short, high-pitched barks that sounded identical to the human ear. When Slobodchikoff ran them through spectrographic analysis, the acoustic structure of each call was measurably distinct.

That was interesting. What came next was unprecedented.
Slobodchikoff noticed that the calls varied not just by predator species but by individual predator. The same colony produced slightly different alarm calls for different humans walking the same route. He had what he later described as a sudden intuition. What if they are describing the physical features of each predator.

He tested it. He sent humans of different heights, different body sizes, and different clothing colors through the colony on controlled walks. He sent dogs of different sizes and colors. He recorded every alarm call and ran discriminant function analysis on the acoustic data. The results showed that prairie dog alarm calls encoded information about the predator's species, size, shape, color, and speed of approach. A tall person in a blue shirt produced a measurably different alarm call than a short person in a yellow shirt. The prairie dogs were not just saying "danger." They were saying what the danger looked like.

The color experiments were particularly striking. Three similar-sized women walked through the colony wearing blue, green, and yellow shirts on separate occasions. The alarm calls for blue and yellow were significantly different from each other. The calls for green were not significantly different from yellow, which matched what was already known about prairie dog color vision. Their visual system cannot reliably distinguish green from yellow. The alarm calls reflected what the prairie dogs could actually see, not what humans assumed they should see.

Slobodchikoff pushed further. He sent novel shapes through the colony, simple plywood cutouts that the prairie dogs had never encountered before. The animals produced alarm calls for shapes they had no evolutionary history with and no prior exposure to. They were not retrieving a stored call from a fixed library. They were constructing new descriptions for unfamiliar objects using the same acoustic building blocks they used for known predators.

That finding is what moved the research from animal behavior into linguistics. Slobodchikoff and his co-authors Bianca Perla and Jennifer Verdolin argued in their book Prairie Dogs: Communication and Community in an Animal Society that the call system meets twelve of thirteen established criteria for language. The calls have syntax. They combine structural elements in novel ways. They transmit specific referential information that other prairie dogs can decode and act on. A prairie dog hearing an alarm call from across the colony does not just run. It runs in the appropriate direction, at the appropriate speed, using the appropriate escape strategy for the specific type of predator the call described.

The escape responses confirmed the calls carried real information. Slobodchikoff played recorded alarm calls through speakers placed inside the colony and watched the behavioral response. Hawk calls sent every prairie dog diving into the nearest burrow. Coyote calls sent them running to the burrow entrance but standing upright at the lip to watch. Human calls produced a slower, more measured retreat. The prairie dogs were not responding to a generic alarm. They were processing the content of the call and selecting an escape strategy calibrated to the specific threat the caller had identified.

Different colonies had different call structures for the same predators. Slobodchikoff documented what he called alarm call dialects, measurable acoustic differences between colonies that correlated with local habitat structure. Colonies in areas with more vegetation produced calls with different frequency components than colonies in open terrain. Playback experiments showed that these structural differences affected how well the calls transmitted through the local environment. The prairie dogs were not just encoding predator information. Their call architecture was tuned to the acoustic properties of their specific habitat.

A two-pound rodent sitting on a mound of dirt in the Arizona grasslands is running a surveillance system that identifies approaching threats by species, size, shape, color, and speed, encodes that information into a sub-second vocalization, broadcasts it across the colony, and triggers differentiated escape responses in every animal that hears it. The entire process, from visual detection to call production to colony-wide behavioral response, takes seconds. A person walking toward a prairie dog town is being described in detail before they have taken ten steps, and every animal in the colony knows what they look like before they can see a single prairie dog looking back at them.

Slobodchikoff trained undergraduate students to visit his colonies for the first time. He told them to listen to the alarm calls. Within two hours, the students could distinguish between the calls for hawks, coyotes, dogs, and humans by ear. The prairie dogs had been saying it clearly the entire time. Nobody had listened closely enough to hear it.

Source: Slobodchikoff, Perla, and Verdolin, "Prairie Dogs: Communication and Community in an Animal Society," Harvard University Press, 2009 / Slobodchikoff et al., "Prairie dog alarm calls encode labels about predator colors," Animal Cognition, 2009

This Week In Science (December 21 – 27)

A storm slowed time, garlic mouthwash, an early Alzheimer's intervention, and much more!

Links to the full articles 📖
Protein https://buff.ly/sSWeweD
Time https://buff.ly/8AB6gQa
Frog https://buff.ly/WVQtBll
Garlic https://buff.ly/1iEh5Mm
Dark matter https://buff.ly/bka8FqC
Alzheimer's https://buff.ly/WhplYLF

This is the oldest rock ever discovered on Earth. It was found in the Nuvvuagittuq Greenstone Belt, Canada, and is more than 4 billion years old.

More about the oldest rock👇
https://earthlymission.com/oldest-rocks-on-earth-discovered-more-than-4-billion-years-old

📷 NASA / Inuit Adventures