Chimpanzees at Kalinzu are known to use sticks to harvest army ants 13 , whereas bonobos at Wamba use tools only in a non-feeding context, e. We assessed the ecological opportunities for tool use based on the availability of insects requiring tools for harvesting i. Bonobos are exceptionally gregarious, with party sizes exceeding those in chimpanzees We investigated whether or not gregariousness reflects close-range social learning opportunities 15 , We assessed the potential opportunities for social learning based on focal observations of immature chimpanzees and bonobos.
Lastly, we investigated the predisposition for tool use by measuring tool use precursors 17 as observable proxies of tool use tendencies, namely object manipulation and object play. We recorded two species of army ants at Kalinzu D. Mean ant density at Kalinzu was 0. Macrotermes mounds were absent at Kalinzu and one species M. Nut trees at Kalinzu consisted of Parinari excelsa at 0. Stones were absent below nut trees at both sites. Distribution of army ants, Macrotermes mounds and ant dipping sites in relation to chimpanzee and bonobo follows at Kalinzu and Wamba maps created using ESRI ArcMap We assessed the social opportunities for learning available to immature chimpanzees and bonobos by comparing the proportion of time spent in close proximity to their mothers, as well as to other individuals.
Next, we compared the mean number of individuals observed within a 2-m radius. Lastly, we compared the number of social partners. We assessed the predispositions for tool use by comparing object manipulation and object play.
The object types manipulated by both species were: leaves, woody vegetation, fruits and moss. First, we compared object manipulation rates between feeding and resting contexts. None of the feeding contexts involved tool use. In addition, we compared object play between young chimpanzees and bonobos.
We also compared the proportion of time in solitary and social play. Lastly, we compared different play types solitary and social, with and without objects. We investigated whether extrinsic or intrinsic differences could explain the remarkably difference in the reliance on tools between wild chimpanzees and bonobos. Our findings showed that ecological and social opportunities did not explain the species difference in tool use. Predispositions, however, did. We recorded more army ant species at Wamba than at Kalinzu, but army ant densities did not differ significantly.
No tools were used to capture army ants by bonobos at Wamba. Tool-assisted army ant predation has been reported for chimpanzee sites with ant densities much lower than Wamba 0.
For example, army ant density is 0. Hence, bonobos at Wamba had sufficient ecological opportunities to dip for army ants. Macrotermes mounds were absent at Kalinzu. The species recorded at Wamba, M. Mound density at Wamba was 0. Hence, Wamba bonobos had ample ecological opportunities to fish for termites. We did not asses tool availability for ant dipping and termite fishing, since raw materials for tools have been shown to be abundant in the forest of the Congo Basin At neither Wamba nor Kalinzu did the apes crack nuts using tools.
Nut tree availability was more varied in Wamba with four species compared to one at Kalinzu. However, Coula edulis , a high value nut and catalyst for cracking of other species 10 , was absent at both sites. Moreover, neither at Wamba nor at Kalinzu did we record stones under nut trees. Hence, ecological opportunities for nut cracking were present at both sites, albeit limited.
Bonobos spent more time in close proximity to their mothers than chimpanzees. There was no species difference in the amount of time spent close to other individuals in a non-feeding context, suggesting that party size differences between the two species did not automatically result in more time in close proximity to others.
However, in a feeding context, bonobos did spend more time in close proximity to other individuals than chimpanzees. These findings confirm higher levels of feeding tolerance in bonobos compared to chimpanzees previously reported for captive apes In sum, young bonobos had more potential opportunities to learn from their mothers, as well as from others when it comes to feeding skills.
In addition, young bonobos had more individuals in close proximity, as well as more social partners than chimpanzees. Recent findings on captive apes reported bonobos as less socially tolerant than chimpanzees and gorillas, since bonobos had fewer neighbours present during tool use However, fewer neighbours during a tool use task could reflect a lack of interest, rather than a lack of tolerance.
Our findings suggest that higher levels of gregariousness and tolerance in bonobos lead to more close-range social learning opportunities and increased access to a variety of social partners from whom to learn. Object manipulation rates were higher in a resting as compared to a feeding context in both species. Objects manipulated by immature chimpanzees did not include tools used by adults.
In fact, immature chimpanzees often manipulated leaves; a material not used by adult Kalinzu chimpanzees in foraging tool use. This suggests that object manipulation by immatures was almost certainly not socially induced and thus not simply a result of young individuals emulating adult feeding tool use.
The different object types targeted by immature chimpanzees and bonobos deserve further investigation Koops et al. Chimpanzees showed higher rates of object manipulation than bonobos. Hence, this further suggests an intrinsic, rather than a directly socially facilitated, difference.
Our findings provide the first evidence for a species difference in object-orientedness, which likely reflects a difference in the predisposition for tool use in Pan. We showed that young chimpanzees and bonobos also differed with regard to object play. Chimpanzees played more with objects than bonobos.
This finding was not a consequence of differences in solitary or social play. The species difference in object play was caused by a difference in solitary play with objects, which was observed more in chimpanzees than in bonobos. These results highlight the important role of play in fine-tuning adult behaviours Chimpanzees engaged more in object manipulation and object play than bonobos, consistent with a species difference in the intrinsic motivation for tool use.
A similar difference in object manipulation was found between the tool-using New Caledonian crows, Corvus moneduloides and the non-tool using common ravens, Corvus corax In both corvids and apes, the predisposition to manipulate objects likely results from a general increase in object-orientedness, rather than a difference in general cognitive capacity.
The question is whether bonobos lost the predisposition for tool use and if so, why? A recent study on captive apes using eye-tracking techniques found a species difference in attention bias.
Bonobos pay more attention to social cues, whereas chimpanzees pay more attention to the action target object Kano et al. Together with our findings this suggests a trade-off between tool use motivation and social attention. The next step will be to assess predispositions across different populations of chimpanzees and bonobos.
If there exists a connection between predispositions and the presence of tool use in chimpanzee populations, this would provide evidence for culture-gene co-evolution.
To conclude, the tool use dichotomy in Pan is driven by intrinsic differences in terms of the motivation to interact with objects. Given their close evolutionary relationship with humans, insights into the tool use difference in Pan can help us identify the conditions that drove the evolution of human technology.
However, that 0. Bonobos and chimpanzees are completely different species, and there are several important physical differences you can use to tell them apart. Male bonobos are about pounds on average, while male chimpanzees weigh in at around pounds. Chimpanzees are also slightly taller than bonobos when they stand up on their back legs, with males averaging 4. Bonobos also have a more slender physique, whereas chimpanzee bodies are more stocky and muscular.
You also can distinguish them by the way they walk. Thus, bonobos remain the lesser known of the two apes and are often confused with chimps or are considered the same animal. In reality, they are two separate species with unique physical characteristics and dynamically different social behaviors. Their genome is about For one, bonobos are small and slender when compared to the taller, stockier chimps. Also bonobos have pink lips and black faces, while chimps have brown lips and faces that change color as they age.
In response to conflict, bonobos release a stress hormone that encourages social bonding for reassurance. In contrast, when presented with the same scenario, chimps secrete testosterone, which is related to aggression. Studies of evolutionary differences between chimps and bonobos have been conducted at many PASA sanctuaries.
Lola ya Bonobo , a PASA wildlife center in the Democratic Republic of Congo, is the only sanctuary for bonobos in the world, helping to rescue, care for, and release them. Research at Lola has found that bonobos are considerate and empathetic, even to strangers. Bonobos prefer to share their meals, even with bonobos not in their social group. One of the ways bonobos avoid conflict related to food sharing is through sex.
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