Scientists have succeeded to decode the bonobo genome, the biochemical instructions in the ape’s cells that guide the building and maintenance of the animal’s body.
It is the last great ape to have its DNA sequence laid bare, following the chimpanzee, orangutan and gorilla.
Comparisons of all their codes, including the human genome, will shed new light on the biology and evolution of these closely related species.
The sequencing and analysis work is reported in the journal Nature.
It was undertaken by an international team led from the Max Planck Institute (MPI) for Evolutionary Anthropology in Leipzig, Germany.
The samples for study were taken from a female bonobo known as Ulindi which resides in Leipzig zoo.
Scientists have succeeded to decode the bonobo genome, the biochemical instructions in the ape's cells that guide the building and maintenance of the animal's body
Bonobos (Pan paniscus), together with chimpanzees (Pan troglodytes), are the closest living relatives of humans.
If one compares the DNA “letters” in the sequences of all three species, there is only a 1.3% difference between humans and their ape cousins.
The separation between the bonobo and the chimp is smaller still. Only four letters in every thousand is changed.
“Based on the differences that we observe between the genomes, one can actually estimate when the last common ancestor between these species lived,” explained MPI’s Kay Prufer.
“And between chimpanzees and bonobos that is maybe a million years in the past. For the chimps, bonobos, and humans – the common ancestor of all three lived somewhere around four to five million years ago,” he said.
Bonobos and chimpanzees live very near to each other in central Africa, but their populations are separated by the Congo River.
Indeed, it has long been thought that the creation of the river about two million years ago was responsible for the divergence of the species. And the new analysis certainly seems to support that hypothesis, with no significant signal of interbreeding detected in the DNA of the apes.
“It seems there was a very clean split,” said Dr. Kay Prufer.
But as similar as their genomes are, bonobos and chimps do display some quite diverse behaviors.
Chimps are very territorial and resort to aggressive actions to resolve conflicts, whereas bonobos are more placid and will use sex as a tool to settle their differences.
The researchers want to learn something about the origin of these behaviors, and the degree to which they are influenced by genetics.
“That’s the great hope,” said Dr. Kay Prufer.
“If you look at bonobos, chimpanzees and humans, what you can see is that there are some specific characteristics that we share with both of them.
“So, for instance, the non-conceptive sexual behavior is a trait that is certainly shared with bonobos, while the aggressive behavior unfortunately is also a trait that is shared with chimpanzees.
“In a way, it is a question of what the ancestor of all three looked like. Which one actually evolved the new trait here?”
To get at some answers, scientists plan to look more deeply at those parts of the genomes where humans share more similarity to bonobos or chimpanzees. It turns out that that more than 3% of the human genome is more closely related to either the bonobo or the chimpanzee genome than these are to each other.
Researchers have found that chimpanzees and orangutans really do have personalities “like people”.
For years experts have debated whether great apes truly display human-like personalities – or if such behavior is simply the anthropomorphic projections of human observers.
The research team used a statistical technique to “remove” any biases apparent in human observers of the apes’ behavior, and they say their findings suggest man and ape really do share “personality dimensions”.
“[Chimpanzees] have the same social problems that we do, they want to make friends and find mates and sort of gain position within their society,” says team member Mark Adams, a researcher who conducted the research while studying for his PhD at the University of Edinburgh, UK.
Dr. Alexander Weiss, senior lecturer at the University of Edinburgh, who also worked on the study, agrees that chimpanzee personality is “highly similar” to that of humans.
Researchers categorize human personality into five “dimensions”, sometimes known as “the big five”, he explains.
“Those dimensions are neuroticism, extroversion, openness to experience, agreeableness and conscientiousness.”
Previous studies into non-human primates suggest that chimpanzees (Pan troglodytes) share these five dimensions with people, whilst orangutans (Pongo pygmaeus and Pongo abelii) display three of the five: extraversion, neuroticism and agreeableness.
These shared personality dimensions are best explained by our genetic similarities, says Dr. Alexander Weiss.
“Humans and chimps share a common ancestor about 4 to 6 million years ago.”
Researchers have found that chimpanzees and orangutans really do have personalities "like people"
The common ancestor for humans and orangutans is thought to have existed fifteen million years ago, which explains why chimpanzees and humans are more similar in personality than orangutans and humans, says Dr. Alexander Weiss.
There is continuing debate amongst experts as to whether scientists should use anthropomorphic projections when studying how animals behave.
Dr. Clive Wynne, professor of psychology at the University of Florida, Gainesville, US describes anthropomorphism as “a mistake” when “trying to understand animal behavior.”
“Human beings have a very natural tendency to project human agency into almost anything that moves,” he says.
“It’s very deeply ingrained into our ways of trying to understand the world around us.”
But despite our inevitable “human perspective” in the way we see the animal kingdom, he says, “since these animals are not us, although it is difficult, we should nonetheless struggle to get our own perspective out of the way and to try and see them for themselves.”
The research team carrying out the study, which features in the journal Animal Behaviour, wanted to test the extent to which human observers of chimpanzee and orangutan behavior might be biased in their reports.
“There’s sort of a fear that human observers and ‘raters’ are projecting their own ideas about personality on to these animals,” says Mark Adams.
But until now, this theory “hasn’t actually really been tested in great apes.”
Members of the research team – who also came from from Kyoto University in Japan and the University of Arizona, Tucson, US – issued questionnaires to around 230 people observing chimpanzees and orangutans in zoos and research centres in the US, Canada, Australia and Japan.
The survey described about 40 to 50 personality “items”, which when grouped together makes personality dimensions.
The human observers – called “raters” – were instructed to rate the apes’ behavior on a one-to-seven point scale for each personality item.
From the questionnaire results, the team determined the type of biases present in the raters’ observations of the animals.
“We used a statistical technique to remove these observer differences before extracting personality traits from the data,” explains Mark Adams.
“What we found is that controlling for these differences among observers made no difference, which suggests that the observers are not projecting their own ideas about personality onto the animals.”
Dr. Alexander Weiss says that the research “vindicates both the view that chimpanzees have personalities and perhaps the more controversial statement that their personalities are quite similar to those of humans.”
• Common chimpanzees (Pan troglodytes) share 98% of human genes and are mankind’s closest living relative. They are thought to be the most intelligent non-human animal
• Chimpanzees are known to modify sticks, rocks and leaves into “tools” to help the gather food such as ants, nuts and honey
• Orangutans are divided into two species: Bornean orangutans (Pongo pygmaeus) and Sumatran orangutans (Pongo abelii)
• The word orangutan translates as “people of the forest”
• They are also capable of learning to use “tools” such as sticks to gather termites. This knowledge is then passed down through the generations
What is “animal personality”?
• Individual animals display different personalities across a range of species, including mammals, fish, birds, insects and molluscs
• These personality traits control whether individual animals are leaders or followers, bold or shy, aggressive or passive, for example. As with people, some animal’s personalities change as they age
• Great tits look for partners that are as outgoing as themselves, while zebra finches with similar personalities make better parents
• Some fallow deer are braver than others, spending less time looking out for predators and being more likely to try new foods
• A fish’s personality may determine how likely it is to be captured – with bold fish more likely to be hooked
