Altruism or manipulated helping? Altruism may have origins in manipulation - [Article]

(Phys.org, 19, Aug 2013) - Manipulation is often thought of as morally repugnant, but it might be responsible for the evolutionary origins of some helpful or altruistic behaviour, according to a new study.

Journal article: Evolution of manipulated behavior (apologies, article not live at time of publishing)

In evolutionary biology, manipulation occurs when an individual, the manipulator, alters the behaviour of another individual in ways that is beneficial to the manipulator but may be detrimental to the manipulated individual. Manipulation not only occurs in humans and animals but also at the cellular level, such as among cells in a multicellular organism, or in parasites, which can alter the behaviour of their hosts. 

Consider the case of the parasitic roundworm (Myrmeconema neotropicum), which once ingested by the tropical ant (Cephalotes atratus) in Central and South America, causes the ant to grow a bright red abdomen, mimicking berries. This bright abdomen constitutes a phenotype manipulated by the roundworm. Birds eat the "berries," or infected ants, and then spread the parasite in their droppings, which are subsequently collected by foraging Cephalotes atratus and fed to their larva, and the cycle of manipulated behaviour begins anew.

In the study published this week in the journal American Naturalist, the researchers developed a mathematical model for the evolution of manipulated behaviour and applied it to maternal manipulation in eusocial organisms, such as ants, wasps, and bees, which form colonies with reproductive queens and sterile workers. In the model, mothers produce two broods, and they manipulate the first-brood offspring to stay in the maternal site and help raise the second brood. 

Mothers can do this by disrupting the offspring's development in some way, for example through poor feeding or aggressive behaviour. Manipulated offspring of the first-brood stay and help to raise the second brood. Alternatively, first-brood offspring can resist manipulation and leave.

The researchers show that an offspring's resistance to manipulation may often fail to evolve, if the costs of resistance are high. In a sense, then, helping or altruistic behaviour is coerced through manipulation.

"The evidence in so-called primitive eusociality, where helping is often coerced through aggression or differential feeding, appears consistent with these results," said lead author Mauricio Gonzalez-Forero, who conducted the study while a graduate research assistant at the National Institute for Mathematical and Biological Synthesis.

The Chimp Ultimatum: Study Reveals Origins of Human Fair Play - [Article]

The Ultimatum Game: When the first chimp takes a token and

 passes it to its partner, this represents an "offer"

(BBC Science, 15, Jan 2013) The human tendency to share may have more ancient evolutionary routes than previously thought.

Journal article: Chimpanzees play the ultimatum game

This is according to a study of the performance of chimpanzees in a test called the "ultimatum game".

Traditionally, the game is employed as a test of economics; two people decide how to divide a sum of money.

This modified game, in which two chimps decided how to divide a portion of banana slices, seems to have revealed the primates' generous side.

The study, published in Proceedings of the National Academy of Sciences, was part of an effort to uncover the evolutionary routes of why we share, even when it does not make economic sense.

Scientists say this innate fairness is an important foundation of co-operative societies like ours.

Lead researcher Darby Proctor from the Yerkes National Primate Research Center at Emory University, US, explained why she and her colleagues chose to use the ultimatum game, which has been used in the past to illustrate the human tendency to share.

During the game, one participant is given an amount of money and asked to "make an offer" to the second player. If that second player accepts the offer, the money is divided accordingly.

But, if the second player refuses that offer, both players receive nothing. This is the basis of the fairness versus economics quandary; if the first player proposes a selfish, unequal offer, the affronted recipient might refuse.

And this is exactly what happens in humans. Although it makes economic sense to give away as little as possible and accept any offer that's proposed, people usually make roughly equal, or "fair" offers, and tend to refuse unequal or "unfair" offers.

Dr Proctor and her colleagues trained their chimp participants to play a similar game, using coloured tokens to represent a reward.

"We tried to abstract it a little - to make it a bit like money," Dr Proctor explained.

A previous attempt to test merit-based sharing among our closest living relatives, the chimpanzees, was published in a 2007 study published in the journal Science. Researchers using the ultimatum game found that chimps would take any reward - no matter what share they were offered. But the authors of this study say this may have been because the chimps were directly offered food which they found "difficult to resist".

While children appear to be prepared to share with a new playmate, non-human primates seem to limit their altruism to close kin and mates. But it is not simply the case that the more intelligent the species the more altruistic they are. Recent research on sharing published in PNAS in social primates revealed that capuchins and marmosets were some of the most "giving" primates - commonly offering food rewards to other group members

Before we feel too superior to our primate cousins, our capacity to be spiteful appears to be ours alone. A 2007 published in PNAS study found chimpanzees, unlike humans, do not retaliate against personally harmful actions. Being spiteful is a human trait

"We trained them with two different tokens.

"If they took [a white token], they would be able to split the food equally, and taking the other [blue] token meant that the first chimp would get more food than the partner."

The researchers presented both tokens to the first chimp, which would then choose one and offer it to its partner.

As with the human version of the game, if the partner accepted the token, both animals received their reward.

Three pairs of chimps played this game, and the results revealed that the animals had a tendency to offer a fair and equal share of the food reward.

In another experiment, the team repeated the test with 20 children between the ages of two and seven. They discovered that both young children and chimps "responded like humans typically do" - tending to opt for an equal division of the prize.

"What we're trying to get at is the evolutionary route of why humans share," explained Dr Proctor.

"Both chimps and people are hugely cooperative; they engage in cooperative hunting, they share food, they care for each other's offspring.

"So it's likely that this [fairness] was needed in the evolution of cooperation.

"It seems to me that the human sense of fairness has been around in primates for at least as long as humans and chimps have been separated."

Dr Susanne Schultz from the University of Manchester said the study was very interesting and showed "the potential for chimps to be aware of fair offers".

"It is interesting that changing the study design - primarily by not using food rewards it seems - one can elicit fairness behaviour in chimps," she told the BBC.

She added though that is was not clear that the chimps completely understood the design of the game and that, with just six chimps involved in the study, further evidence would be needed to show clearly that chimps had a natural tendency towards fairness.

Human Kindness Also Found in Bonobos - [Article]

"I love you generic orange fruit stuff, never leave me"

(NYTimes.com, 7, Jan 2013) - Bonobos will happily share their food with a stranger, and even give up their own meal — but only if the stranger offers them social interaction, evolutionary anthropologists at Duke University report in the journal PLoS One. The researchers, Jingzhi Tan and Brian Hare, say their findings may shed light on the origins of altruism in humans.

Journal article: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0051922

Along with chimpanzees, bonobos are among the closest primates to humans. Chimpanzees, however, do not display similar behaviour toward strangers.

“If you only studied chimps you would think that humans evolved this trait of sharing with strangers later,” Mr. Tan said. “But now, given that bonobos do this, one scenario is that the common ancestor of chimps, humans and bonobos had this trait.”

The subjects were all orphaned bonobos at the Lola ya Bonobo sanctuary in the Democratic Republic of Congo. In one phase of the study, bonobos were given a pile of food, then given the opportunity to release a stranger or a group mate (or both) from other rooms.

The bonobos chose to release strangers and share their food. Not only that, but the just-released bonobo would then release the third.

“This was shocking to us because chimpanzees are so xenophobic,” Mr. Tan said. “They won’t approach a stranger unless they outnumber them.”

The apes did have a limit — they would not share their own food when no social interaction was involved.

They were, however, willing to help a stranger get food even without social interaction. Mr. Tan compared this to certain human acts of kindness.

“It’s like when you donate money and you don’t tell people,” he said, “so there’s no way for you to get any benefit.”