So scientists were thinking "hmm, maybe perception of geometric regularity is a unique skill to homo sapiens?". It turned out that crows can tell a square from trapezoids, too.
And it genuinely takes a lot of time when dealing with reasonably complex animals.
It reminds me of the research on cinereous tits, where the researcher had to spend like half a year at a time to validate a given chant matches a given word.
Most people in active testable science have worldviews where they suspect many relationships about the world that have not been strongly validated. Einstein was not the first person to discuss how space and time seem inextricably related in a special way; pythagoras was not the first to figure out how to derive the third side of a right triangle; galileo was not the first to suggest a heliocentric worldview; etc etc. Demonstrating things that seem obvious or intuitive or that are already assumed and used practice is still immensely valuable. Communication is hard, and demonstrating things about the world without getting tangled up in the inherent unsuitability of language to precisely describe the world is incredibly, incredibly difficult. We are still validating knowledge that the ancients practiced on a daily basis. Galen certainly never bothered to persuade; only to inform.
It nearly makes me want to ban articles if the paper is available. The discussion inevitably sags.
Many people historically and presently see themselves as the pinnacle of a godly creation, so they put humans above everything and anything, meaning that most perspectives to validate or not are about how unique we are. It might be annoying or backwards but at least there are people out there still willing to chip at it, one study at a time.
As a sibling indicated baboons can not distinguish these shapes easily. Additionally, rather than a binary "crows can recognize shapes" the study shows how well crows process the shapes. One of the graphs in the paper, but not the article shows that two different crows have a similarly hard time with the rhombus.
In other studies, this same test was applied to humans to find that it is a fairly innate skill rather than developed by doing geometry in school.
And crows? Humans have been battling crows since the beginning of agriculture. It takes some serious effort to crow-proof everything on a farm.
Anyone who's ever argued that you shouldn't feed crows because it interferes with nature hasn't figured out that crows already adopted to urban human-inhabited environments, and feeding them quality food (cat kibble is cheap and works) is very much a net positive. If you see crows with white feathers, that's malnutrition, and you should give them something good to eat.
For apes and gorillas we can communicate. We've taught them sign language so we know hands down in terms of language we beat them. But for dolphins and octopi, we just don't really know.
It might seem remarkable that they can do this in a structured setting like humans do, but the more I learn about animals… The less remarkable I think this kind of behaviour is.
This one shows that they can distinguish shapes even slightly different from another. I think it is still significant and interesting.
Edit, to add: years ago a lot of people kept pigeons in rooftop coops around NYC. As a kid there was an older guy near by who you'd see on his roof waving around a cloth that sort of directed the birds as they flew in a big flock. Now I'm imagining that but a flock of crows bringing back loot to some gangster on a rooftop.
I guess you also need to make sure whether the crows are properly classified as employees or independent contractors.
The book is a sequel, of sorts, to Children of Time and Children of Ruin, and they should be read in sequence.
All three books grapple with "what is intelligence?" by using approximately familiar devices to land definitions that might otherwise be too alien.
Crows are the first that come and after some tasting, stuff their peaks with meat and leave. The fuckers sit on the top of the neighboring house and watch if I'm at home. If they see I'm roaming around they fly to the window and start marching. Marching means they walk up and down on the galvanised plate-covered ledge signaling me, that they want some treats.
If you ignore them for too long or don't have any leftover cheese or meat for them they come over, pull out the fresh plants from the ground and leave. :D