There have been three interesting stories in the past week on primate psychology -- each of which shows that we humans are not so unique as we think we are. This is comforting to me. It's nice to know that other species experience life in ways similar to the we do.
Great apes think ahead
Study provides conclusive evidence of advanced planning capacities in nonhuman speciesApes can plan for their future needs just as we humans can – by using self-control and imagining future events. Mathias and Helena Osvath's research, from Lunds University Cognitive Science in Sweden, is the first to provide conclusive evidence of advanced planning capacities in non-human species. Their findings are published online this week in Springer's journal, Animal Cognition.
The complex skill of future planning is commonly believed to be exclusive to humans, and has not yet been convincingly established in any living primate species other than our own. In humans, planning for future needs relies heavily on two mental capacities: self-control or the suppression of immediate drives in favor of delayed rewards; and mental time travel or the detached mental experience of a past or future event.
In a series of four experiments, Mathias and Helena Osvath investigated whether chimpanzees and orangutans could override immediate drives in favor of future needs, and therefore demonstrate both self-control and the ability to plan ahead, rather than simply fulfill immediate needs through impulsive behavior.
Two female chimpanzees and one male orangutan, from Lund University Primate Research Station at Furuvik Zoo, were shown a hose and how to use it to extract fruit soup. They were then tempted with their favorite fruit alongside the hose to test their ability to suppress the choice of the immediate reward (favorite fruit) in favor of a tool (the hose) that would lead to a larger reward 70 minutes later on (the fruit soup). The apes chose the hose more frequently than their favorite fruit suggesting that they are able to make choices in favor of future needs, even when they directly compete with an immediate reward.
New tools the apes had not encountered before were then introduced: one new functional tool which would work in a similar way to the hose, and two distractor objects. The apes consciously chose the new functional tool more often and took it to the reward room later on, where they used it appropriately, demonstrating that they selected the tool based on its functional properties. According to the authors, this indicates that the apes were pre-experiencing a future event i.e. visualizing the use of the new tool to extract the fruit soup.
One of the decisive experiments excluded associative learning* as an explanation of the results. Associative learning has been suggested to account for the findings in previous planning studies on animals (corvids and great apes), and therefore the previous studies have not been generally accepted as evidence for non-human planning.
Taken together these results strongly suggest that great apes engage in planning for the future. The authors conclude that "the results of this study entail that capacities central to humans evolved much earlier than previously believed."
###*A learning principle based on the belief that ideas and experiences reinforce one another and can be mentally linked to enhance the learning process.
Reference
1. Osvath M & Osvath H (2008). Chimpanzee (Pan troglodytes) and orangutan (Pongo abelii) forethought: self-control and pre-experience in the face of future tool use. Animal Cognition; DOI 10.1007/s10071-008-0157-0
Male monkeys prefer boys' toysIt's thought of as a sexual stereotype: boys tend to play with toy cars and diggers, while girls like dolls. But male monkeys, suggests research, are no different (see a related video report).
This could mean that males, whether human or monkey, have a biological predisposition to certain toys, says Kim Wallen, a psychologist at Yerkes National Primate Research Center in Atlanta, Georgia.
Wallen's team looked at 11 male and 23 female rhesus monkeys. In general the males preferred to play with wheeled toys, such as dumper trucks, over plush dolls, while female monkeys played with both kinds of toys.
This conclusion may upset those psychologists who insist that sex differences – for example the tendency of boys to favour toy soldiers and girls to prefer dolls – depend on social factors, not innate differences.
Guys and dolls
"A five-year-old boy whose compatriots discover has a collection of Barbies is likely to take a lot of flak," Wallen says.
Social factors undoubtedly influence children's preferences, he says, but in general boys tend to be pickier with toys than girls.
To try and tease out the effects of nature over those of nurture, Wallen and his colleagues studied a group of captive rhesus monkeys. His team reasoned that the choices of the monkeys wouldn't be determined by social pressures. Most of the study animals were juvenile (age one to four years), but some sub-adult and adult monkeys were included.
"They are not subject to advertising. They are not subject to parental encouragement, they are not subject to peer chastisement," Wallen says.
Monkey fun
Wallen's team offered the monkeys two categories of toys: "wheeled" and "plush". The wheeled toys, intended to be masculine, included wagons and vehicles. The more feminine plush toys included Winnie the Pooh and Raggedy-Ann dolls.
Two toys, one wheeled and one plush, were placed 10 metres apart. At first the monkeys formed a circle around a toy, but eventually one would snatch the toy and run off. Other monkeys soon joined in the fun, Wallen says.
The researchers captured play sessions on video and measured how long each monkey spent with plush versus wheeled toys. The team found that the males spent more time playing with wheeled toys, while the females played with both plush and wheeled toys equally.
'Compelling results'
Wallen cautions against over-interpreting the results. The plush and wheeled categories served as proxies for feminine and masculine, but other toy characteristics, such as size or colour, might explain the male's behaviour, he says. Or the male monkeys might seek out more physically active toys, he says.
But the study ties in with a previous experiment with green vervet monkeys showing that males favour masculine toys.
"Together the results are compelling," says Gerianne Alexander, a psychologist at Texas A&M University in College Station, who led the vervet monkey study.
She thinks that biological differences between sexes start the ball rolling toward learned preferences for play toys.
"There is likely to be a biological tendency that is amplified by society," she says.
Journal reference: Hormones and Behavior (DOI: 10.1016/j.yhbeh.2008.03.008)
So, this might suggest that there is an inherent preference in boys for certain kinds of toys, as most parents would likely tell you.
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This is the coolest study of the group.
Study: Chimps calm each other with hugs, kisses
WASHINGTON - For most folks, a nice hug and some sympathy can help a bit after we get pushed around. Turns out, chimpanzees use hugs and kisses the same way. And it works. Researchers studying people's closest genetic relatives found that stress was reduced in chimps that were victims of aggression if a third chimp stepped in to offer consolation.
"Consolation usually took the form of a kiss or embrace," said Dr. Orlaith N. Fraser of the Research Center in Evolutionary Anthropology and Paleoecology at Liverpool John Moores University in England.
"This is particularly interesting," she said, because this behavior is rarely seen other than after a conflict.
"If a kiss was used, the consoler would press his or her open mouth against the recipient's body, usually on the top of the head or their back. An embrace consisted of the consoler wrapping one or both arms around the recipient."
The result was a reduction of stress behavior such as scratching or self-grooming by the victim of aggression, Fraser and colleagues report in Tuesday's edition of Proceedings of the National Academy of Sciences.
Dr. Frans de Waal of the Yerkes Primate Center at Emory University in Atlanta said the study is important because it shows the relationship between consolation and stress reduction. Previous researchers have claimed that consolation had no effect on stress, said de Waal, who was not part of Fraser's research team.
"This study removes doubt that consolation really does what the term suggests: provide relief to distressed parties after conflict. The evidence is compelling and makes it likely that consolation behavior is an expression of empathy," de Waal said.
De Waal suggested that this evidence of empathy in apes is "perhaps equivalent to what in human children is called 'sympathetic concern.'"
That behavior in children includes touching and hugging of distressed family members and "is in fact identical to that of apes, and so the comparison is not far-fetched," he said.
While chimps show this empathy, monkeys do not, he added.
There is also suggestive evidence of such behavior in large-brained birds and dogs, said Fraser, but it has not yet been shown that it reduces stress levels in those animals.
Previous research on conflict among chimps concentrated on cases where there is reconciliation between victim and aggressor, with little attention to intervention by a third party.
Fraser and colleagues studied a group of chimps at the Chester Zoo in England from January 2005 to September 2006, recording instances of aggression such as a bite, hit, rush, trample, chase or threat.
The results show that "chimpanzees calm distressed recipients of aggression by consoling them with a friendly gesture," Fraser said.
Consolation was most likely to occur between chimpanzees who already had valuable relationships, she added.
The research was supported by the Leakey Trust.
A little empathy is all we need.
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well, i never knew that social factors have a big effect on sex differences like what adult toys girls or boys should play. Anyway, it was a cool and informative read for me.
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