[LINK] Two links on primate intelligence

[rfmcdonald]

The Atlantic's Lindsay Abrams reports in "Monkeys Can't Pick Up Musical Beats" that rhesus monkeys can't pick up the changing rhythm of music.

PROBLEM: You know how humans are always insisting on clapping along at concerts? Beat induction -- being able to pick up a song's basic units of time -- is integral to our appreciation of music, allowing us to nod, dance, and -- if we must insist upon it -- clap without looking entirely ridiculous being off-rhythm. Even newborn babies are able to follow along to music in this way. And even though it's invariably awkward, it might actually, from an interspecies perspective, be pretty impressive.

METHODOLOGY: Researchers at the University of Amsterdam and the National Autonomous University of Mexico took methodology used to study beat detection in infants and adapted it for rhesus monkeys. Their two subjects, Aji and Yko, were hooked up to electrodes that measured their brain signals while they listened to rhythms played on a drum. This was a more scientific way of doing it than just seeing whether they nodded along: They would omit the downbeat from strictly metrical music and see if Aji and Yko's monkey brains registered the syncopation.

Aside from the dubious ethics of making monkeys listen to excessive drumming, the researchers did everything possible to ensure their subjects' comfort, right down to arranging it so that "the animals were seated comfortably in a monkey chair where they could freely move their hands and feet."

RESULTS: Aji and Yko were able to detect the music's basic rhythm. But omitted beats, which to humans would sound "as if the rhythm was broken, stumbled, or became strongly syncopated for a moment," went unnoticed by their monkey brains.

CONCLUSION: After comparing the monkeys' brain signal patterns to those of humans, the researchers concluded that "rhesus monkeys, contrary to what has been shown for human adults and newborns, show no sign of representing the beat in music."

ScienceNOW Rebecca Widiss, writing at Wired in "Tool-Using Orangutans Learn Like Humans", suggests that (smarter?) orangutans, meanwhile, possess something like regional cultures, at least insofar as tool use is concerned.

Like humans, orangutans have behavioral traditions that vary by region. Orangutans in one area use tools, for example, whereas others don’t. Take the island of Sumatra, in western Indonesia. By the age of 6 or 7, orangutans from swampy regions west of Sumatra’s Alas River use sticks to probe logs for honey. Yet researchers have never observed this “honey-dipping” among orangutans in coastal areas east of the water.

How do such differences arise? Many experts say that social learning is key — that the apes figure out how to honey-dip by watching others. But even the most careful field researcher can have difficulty proving this, says Yale University anthropologist David Watts. Wild apes are always responding to their environment, he says. And it may be influencing their behavior far more than social learning.

An unfortunate series of events has finally allowed scientists to test social learning’s importance. Deforestation has caused a large number of orangutan orphans, many of whom come from both sides of the Alas River, to wind up at the Batu Mbelin shelter in northern Sumatra. At first they’re quarantined, and then they move to large social groups.


Psychologist Thibaud Gruber of the University of Zurich’s Anthropological Institute & Museum in Switzerland and his colleagues began studying Batu Mbelin’s quarantined apes because political unrest made it unwise for the researchers to work in the field. The team gave the orangutans two stick-based challenges: raking food into their cage and dipping for honey. Apes from both sides of the river picked up the raking behavior relatively quickly. This suggests that all of the animals could understand sticks as tools, Gruber says. But while nine of 13 west-side apes “knew” to honey-dip, only two of 10 east-side apes did, Gruber’s team reports this month in Current Biology. What’s more, the savvy west-side apes were just 4 years old on average — too young to have begun honey-dipping when they were in the wild. Gruber says this indicates that specific ways of using tools come from observing others.

The young orangutans who “knew” to honey-dip likely formed the idea of honey dipping in their heads before they were physically able to do it, Gruber says. And when it came to applying this idea years later, they had little trouble. Gruber calls such mental representations of stick use “cultural ideas.” If they really exist, he says, then behavior differences among apes are closer to human cultural differences, which also often stem from ideas.