A couple of weeks ago, Jane Goodall appeared on PBS on Bill Moyers Journal. You can watch the video online.
Natural History magazine has published an article by Frans de Waal that is excerpted from his recent book, The Age of Empathy. He discusses the bodily basis for feelings of empathy, from shared laughter, shared yawns, and other forms of physical synchrony across a variety of species. (The sequence of images of a yawning primate had me yawning too.) His focus is on the often instinctive and unconscious way that our bodies synch up with those of others, providing the basis for more conscious thoughts and feeling related to empathy.
The latest National Geographic contains this story about animal intelligence. It’s a nice roundup of the latest on the cognitive capabilities of species including chimpanzees, birds, dolphins, and dogs. The more we look at the minds of other species, the more we realize that intelligence isn’t a feature that was somehow added to living things at some point in the evolution of genus Homo, but rather a range of abilities that have arisen across a variety of evolutionary lineages. It’s fascinating to be learning so much about what goes on behind the eyes of other critters.
Some unexpected modern-day chimp behavior may have implications that affect our view of human evolution. Based on some strong circumstantial evidence, researchers concluded that chimpanzees living in woodland savanna in western Tanzania use sticks to dig out underground food sources like roots and tubers. Some scientists have been wondering for awhile if carbohydrates and other food sources found through gathering might have had more of an effect on human evolution than hunting for meat. If the behavior of our early hominid ancestors was similar to the behavior of these chimps, this discovery may provide the latest piece in that particular puzzle.
The surprising thing is that the chimps do this not during the dry season when food above ground is scarce, but at other times of the year when other kinds of food are available. If early hominids also exploited this particular food source, maybe our view of this type of food as a fallback when times were hard is not accurate, and instead it gave an added advantage even when there were plenty of other things to eat.. The puzzle is still missing some pieces, but this is an interesting advance anyway. This article from Live Science has more details.
The ultimatum game is a tool of experimental economics. In this game, a person is given some money to divide between himself and another person. The other person can accept or reject the division. If he accepts, each gets to keep his or her share of the money as decided by the divider. If he rejects it, neither person gets anything. On the one hand, you might think that since it’s better to get something than nothing, people would be inclined to accept even badly skewed divisions, and so there would be no reason not to make such a division (e.g., $9 for me, $1 for you). However, people tend to make offers that are close to 50-50, and offers that give the responder too small a cut are often turned down. Obviously something beyond a narrow interpretation of self-interest is operating here: a sense of fair play and the belief that it’s worth punishing a greedy person even if it costs you something.
That’s with humans. With chimps, it’s a different story. Researchers at the Max Planck Institute of Evolutionary Anthropology in Germany have set up a modified version of the ultimatum game for chimps that involves trays of raisins. The game used a gizmo that required both chimps to work together to access the raisins. One could choose an equal or unequal division of raisins, and slide the tray out as far as he could; the other could then decide whether to slide the tray the rest of the way so both chimps could eat. As long as a chimp got some raisins–even if he got 2 and the other got 8–he would cooperate. The only scenario that was routinely rejected was a 10-0 split, in which there was nothing at all for one chimp. So it looks like chimps are not motivated by humans’ interest in fair play. I wonder what would happen with bonobos. You can read more at this press release.
The reasons that humans help others are complicated, and certain aspects of human altruism have been thought to be unique to us. Even our close relatives, the chimpanzees, were thought to lack certain key components of altruism, like being willing to help someone who is not related without expecting some kind of payback. Recent research carefully examined helping behavior in chimps and in human toddlers and discovered some interesting things indicating that perhaps our altruistic behavior is rooted in capabilities also possessed by chimps. In two experiments that compared chimps and 18-month-old humans, researchers found that both showed a similar propensity for helping a stranger, even when no reward was involved and even when helping the stranger involved some effort. (The only difference was that the humans were a little faster and the chimps were more likely to need additional cues that help was needed before they would respond.) A third experiment looked only at chimps, and indicated that chimps are able to use a newly learned skill to help another chimp get to food, without pestering the other for a share. The paper in PLoS Biology contains all the details, including some video sequences, and an author summary at the top if you want just the basics.
This morning I heard a story on NPR about chimp and bonobo communication. Frans de Waal and others at Emory have studied the gestures that chimps and bonobos make, as well as their facial expressions and vocalizations, and have determined that the gestures are used more flexibly than the other two types of communication. Gestures may have different meanings depending on context, and they vary between groups. The fact that the gestures are used more creatively indicates that they might represent a precursor to human language. This press release from Emory has additional information comparing chimps and bonobos (the latter likely communicate more like our distant hominid ancestors did). I hadn’t realized that gestures also appear to have evolved more recently than either vocalizations or facial expressions, based on the fact that the latter appear in monkeys but only apes and humans use gestures. I’m assuming this study looked at captive animals at the primate research center at Emory rather than animals in the wild.
A paper recently published in PLoS Genetics presents evidence that humans and chimps separated into distinct species about four million years ago, a relatively recent estimate for the time of the split. Researchers analyzed the chimp, human, and gorilla genomes using a statistical technique that had not previously been applied to genetics. The four-million-year date doesn’t jibe with some of the fossil evidence we have about the split, so this is obviously a “to be continued” story. You can read about this latest result in this story from Live Science or this article from Reuters. You can also read the entire paper.