When Mr Rogers told viewers of his beloved children’s TV show to “look for the helpers,” bonobos clearly weren’t paying attention. A new study of one of our closest living relatives finds that these docile apes prefer individuals who hinder over those who help.
The findings, described in the journal Current Biology, could shed light on the origins of “prosocial” behaviour in human beings.
“A preference for helpers over hinderers,” the study authors wrote, may have “played a central role in the evolution of human development and co-operation.”
Bonobos, together with chimpanzees, are two of humans’ closest living relatives — and while they look fairly similar, there are many significant differences in their behaviours and social structure. Chimps have a tendency to engage in violent conflict; bonobos do not. Chimp social groups are male dominated, whereas bonobo groups are female dominated.
Because bonobos appear to be more prosocial — that is, they act in ways that foster social bonds and benefit the larger social group — scientists have long wondered if they may share such characteristics with humans, a highly co-operative species.
“As the most socially tolerant nonhuman ape, bonobos (Pan paniscus) provide a powerful phylogenetic test of whether this trait is derived in humans,” the study authors wrote. “Bonobos are more tolerant than chimpanzees, can flexibly obtain food through co-operation, and voluntarily share food in captivity and the wild, even with strangers. Their neural architecture exhibits a suite of characteristics associated with greater sensitivity to others.”
So do bonobos value co-operative, prosocial behaviours in the way humans do? In humans, that preference starts young: Babies as young as 3 months old have been shown to favour people who they witness helping others.
To find out, researchers from Duke University set up a series of four experiments to test semi-free-ranging bonobos at the Lola ya Bonobo sanctuary in the Democratic Republic of Congo.
Half of the experiments involved animations of two-dimensional, cartoon-eyed shapes that helped or hindered each other. For example, in the first experiment bonobos watched videos of a circle (with eyes) trying to climb a steep hill, and failing. In one version, a triangle with eyes helped push the struggling circle up the hill. In another, a square with eyes shoved the circle back down. (The researchers also showed control versions of these films, in which a plain, eyeless circle was pushed up or down a hill.)
A bonobo was then offered a choice between two slices of apple, each with a different paper shape on it. To their surprise, the researchers found that only two bonobos chose the helper shape on a majority of the trials; 11 of them chose the hinderer.
“This finding suggests that bonobos can discriminate between prosocial and antisocial agents but that they do not show the human preference for prosocial agents,” the study authors wrote.
The next two experiments involved live-action entertainment. Three humans acted out a little scene: One played with a toy and then dropped it; a second person picked it up and returned it, and a third person snatched the toy away. The helping and hindering humans then stepped forward, each presenting a fruit slice to the observing bonobo. Again, the bonobos largely preferred the offering from the hinderer, and not the helper.
If bonobos are so tolerant and social, why do they seem to prefer antisocial individuals, whether animated or human? It may be that antisocial behaviour is associated with dominance — and dominance still plays a role in these apes’ lives.
To test that, the researchers ran another animated experiment. This time, the videos presented two different scenarios. In the first, a cartoon-eyed trapezoid tried to enter a circle on the ground, and a cartoon-eyed pentagon repeatedly shoved it out, claiming the circle as its own. In the second, a square and triangle (both with eyes) took turns hanging out in the circle. Again, when presented with shape-covered fruit slices, the bonobos tended to go for the pushy pentagon.
Theoretically, being a hindrance and being dominant are not inextricably linked; one could potentially be helpful and dominant, or antisocial and submissive. But differentiating between apes’ reactions those two distinct qualities will need to be sorted out in future work, the researchers said.
This preference was only significant in the adult bonobos, and not the younger ones — to a certain point, given that none of the bonobos tested were under 4 years old. Because of that, the researchers couldn’t fully determine whether this antisocial/dominant preference existed in bonobo infants, or whether it developed later.
Regardless, the findings could indicate that such a prosocial preference might be a particularly human trait, the study authors said.
“Our results support the predictions of the dominance hypothesis and raise the possibility that the motivation to prefer prosocial individuals evolved in humans after their divergence from the other apes,” the scientists wrote.
The next step is to study these behaviours in other species of apes, including chimpanzees, the researchers said. — Los Angeles Times/TNS

Robots do chin-ups, push-ups and sit-ups for the sake of science
By Amina Khan

A team of Japanese engineers has designed robots that can perform pushups, do crunches, stretch and even sweat while doing so.
The robots Kengoro and Kenshiro, described in the journal Science Robotics, can perform remarkably human-like movements — and could serve as a model to help scientists design better crash dummies and prosthetic limbs and to better understand the moving human body’s mysterious inner workings.
Researchers have been developing humanoid robots for years, each becoming more advanced than the last — but there are still a number of kinks to work out, the study authors wrote.
“A limitation of conventional humanoids is that they have been designed on the basis of the theories of conventional engineering, mechanics, electronics and informatics,” the study authors pointed out.
That’s in part because conventional robots are often made of rigid, unforgiving parts, whereas human bodies (aside from their skeletons) are made of more pliant materials, such as skin and muscle and cartilage, giving them greater flexibility and adaptability to an unpredictable environment.
Traditional robots, the study authors added, are usually built with a particular application in mind — to help with daily tasks or respond to disasters, for example.
“By contrast, our intent is to design a humanoid based on human systems — including the musculoskeletal structure, sensory nervous system, and methods of information processing in the brain — to support science-oriented goals, such as gaining a deeper understanding of the internal mechanisms of humans,” the scientists wrote.
Such a robot could help researchers better understand how our own bodies really work, by giving them a real-life model to experiment with.
“The features crucial for improving humanoids are hidden behind the structure and motion processes of humans,” they wrote. “Hence, we incorporated elements that facilitate fidelity with the human musculoskeletal system.”
To design Kenshiro and Kengoro, the scientists used human statistical data to give the robots more humanoid proportions, both in their mass distribution and in the size of each body part. They set up the skeletal structure and tendon-driven actuator systems that were meant to echo the connections made by muscles and tendons in the human body. Finally, they tried to design the joints to mimic those in human bodies.
Humans have 548 degrees of freedom at their joints, allowing for a remarkable and complex range of movement; if you leave out the face and hands, there are still a whopping 419 degrees of freedom, the authors said.
Standard axial-driven humanoid robots, such as ASIMO (known for playing soccer with President Obama) or HRP-2 (which competed in the DARPA Robotics Challenge in Pomona in 2015), have far fewer joint degrees of freedom: around 27 to 55, the study authors wrote.
But tendon-driven robots like Kenshiro and Kengoro, with their human-inspired musculoskeletal structures, have about double that, from 55 to 114 joint degrees of freedom. Kenshiro has 64 degrees of freedom, thanks to multiple spine joints (structured in a human-like S-curve) and a more humanoid knee joint. Kengoro has 114 degrees of freedom — or 174, if you include all the joints in its hands.
Kengoro does have fingers and toes, but they still have a way to go to match the musculature of human digits, the study authors wrote. Given how important these “end effectors” are to human life, improving those is key, they said.
“End effectors are quite important for humans in their daily lives,” the researchers said. “This suggests that it is essential to develop human mimetic end effectors to move humanoid robotics forward.”
The researchers even designed Kengoro to sweat, developing an artificial perspiration system to release heat from the motors.
The scientists say incorporating these kinds of humanoid characteristics could help reveal the invisible inner workings of human bodies — and find better ways to prevent and treat illness and injury.
“One research group has suggested the possibility that a musculoskeletal humanoid can be used in medicine, such as to grow tissue grafts,” the scientists pointed out. “If a humanoid can replicate human movements, then the resulting muscle contribution analysis or sensory data obtained during motion will benefit athletes or sports trainers.” — Los Angeles Times/TNS