Nick Carne
It’s been quite a day for revelations about the animal world. Four papers in peer-reviewed journals have provided new insights into what a few species do when they’re going about their business.
Meerkats first. According to a British team, they are a bit more aggressive than you might imagine, and even do a “war dance” to frighten opponents and protect their territory.
Displaying an erect tail and puffed-out fur is likely an attempt to appear larger, say researchers from University College London and the University of Cambridge in a paper in the journal Proceedings of the Royal Society B.
They monitored hundreds of intergroup encounters over 11 years and discovered that meetings between meerkat clans often turn aggressive and sometimes escalate to fighting and lethal violence.
Aggressive in its own way is the accumulative stone throwing (AST) used by some chimpanzees as a form of communication. A German / French research team studied the types of trees they like to throw stones at and found that they chose the ones with a bit of bass.
“We measured three acoustic descriptors related to intrinsic timbre quality and found that AST tree species produced impact sounds that were less damped, with spectral energy concentrated at lower frequencies compared to non-AST tree species,” the researchers write in the journal Biology Letters.
Whales, it is well known, like to sing, but Australian and Scottish researchers have now discovered that the songs of humpback whales (Megaptera novaeangliae) follow consistent rules.
“We analysed songs from east Australian humpback whales over 13 years. These song patterns are known to change yearly, yet males continually conform to these changing patterns,” says Jenny Allen from the University of Queensland, lead author of a paper in the journal Proceedings of the Royal Society B.
“We found that all songs had structural similarities which may facilitate learning, explaining the song’s rapid and consistent spread through entire populations. These structural patterns also occur in several bird songs, indicating different species share grammatical rules.”
And finally to dogs which, it seems, share a significant skill with humans – the ability to count.
Dogs spontaneously process basic numerical quantities, using a distinct part of their brains that corresponds closely to number-responsive neural regions in humans, according to a study by researchers at Emory University, US, published in Biology Letters.
And this, they say, suggests that a common neural mechanism has been deeply conserved across mammalian evolution.
“Our work not only shows that dogs use a similar part of their brain to process numbers of objects as humans do – it shows that they don’t need to be trained to do it,” says senior author Gregory Berns.
The study used functional magnetic resonance imaging (fMRI) to scan dogs’ brains as they viewed varying numbers of dots flashed on a screen. The results showed that the dogs’ parietotemporal cortex responded to differences in the number of the dots.
The researchers held the total area of the dots constant, demonstrating, they say, that it was the number of the dots, not the size, that generated the response.
Humans and dogs are separated by 80 million years of evolution, Berns says. “Our results provide some of the strongest evidence yet that numerosity is a shared neural mechanism that goes back at least that far.”
