Chimpanzee using tool

Such active transfers were never observed at Gombe, where mothers most often responded by refusing to transfer tools. Given that offspring in both populations made comparable requests for tools, these differences suggest that mothers at Goualougo were in fact more willing to provide tools. Understanding how chimpanzees pass on tool traditions over generations can provide insights into the evolutionary origins of complex cultural abilities in humans.

Conservation efforts are fundamental to this research and future studies. Studying our closest living relatives offers a unique opportunity to gain insights into the evolutionary origins of cultural behavior—but this privilege depends on long-term efforts to conserve these apes and their habitats. Additional researchers are from Washington University in St. Source: Washington University in St.

Search for:. Science Health Culture Environment. Play Video. Share this Article. You are free to share this article under the Attribution 4. Are really tiny tools what make humans special? Among chimpanzees, the number of individuals present in a party has been used as a proxy for social learning opportunities [ 57 , 58 ].

However, the number of individuals present in a party may not be as important as the number of individuals engaged in tool use, close proximity of tool using models, actual time spent tool using, connectivity within the group and potential types of social facilitation.

Research examining the theoretical importance of social networks [ 59 ] and diffusion of tool using conventions through social groups [ 60 ] may provide a more implicit means to test the invention hypothesis.

Recent field studies have also examined the social context of tool use in natural settings [ 30 , 40 , 61 ], where some technological traditions have presumably been maintained over generations and vast landscapes. In this study, we examine whether the frequency, diversity and complexity of tool use within a population of chimpanzees residing in the Goualougo Triangle of the northern Republic of Congo is correlated with necessity, opportunity, relative profitability or invention.

According to the necessity hypothesis, foods gathered with tool use would compensate for reduced abundance of ripe fruits. According to the opportunity hypothesis, tool use would track the relative abundance of particular tool targets termites, ants, honey, etc. The relative profitability hypothesis suggests that tools will be used to harvest embedded food items when energy intake rates outweigh those attained by conventional foraging for more easily accessible food items.

With regard to the invention hypothesis, we predict that more frequent or complex tool use will occur in settings with enhanced opportunities for social transmission. The Goualougo chimpanzee population has a relatively diverse repertoire of tool using behaviour, which includes the regular use of several tool sets and particular tool modifications that have been shown to increase foraging efficiency [ 62 ].

Therefore, this investigation bears directly on the question of the current adaptive significance of tool-assisted foraging in wild animals and provides insights into the evolution of complex technology within our own lineage.

The climate in the northern Republic of Congo can be described as transitional between the Congo-equatorial and subequatorial climatic zones. Direct observations of the chimpanzees in the Goualougo Triangle have been ongoing since February Individual chimpanzees were identified from their distinct physical characteristics held in a population history database. The main study group is the Moto community which consisted of 71 individuals at the time of this study, including 17 adult males and 24 adult females.

This chimpanzee population exhibits a diverse repertoire of tool using behaviours which occur in a variety of contexts [ 15 ]. Tool using behaviours have been documented through direct observation during reconnaissance surveys of chimpanzees since the initiation of research at this site.

In , we also began remote video monitoring of tool use sites. Video footage of tool using behaviour is recorded whenever possible. This study focuses on annual profiles of tool use in foraging for termites Macrotermes muelleri , M.

We assessed the frequency of tool use in the termite gathering context from remote video recordings conducted between March and June Remote video monitoring units consist of video cameras in weatherproof housing that are triggered to record for pre-set intervals by passive infrared sensors for a more detailed description of these methods, see [ 53 ].

These cameras were placed at termite nests with previous traces or observations of chimpanzee tool use. Six mature females and five mature males were confirmed to exhibit tool using behaviour at termite nests monitored with video cameras at least once per year throughout the study period.

A tool using episode was defined as beginning when the chimpanzee manufactured a tool or at the first moment after which they were observed with the tool and ended when the tool was discarded or the task was abandoned.

Frequency of ant dipping was assessed through chimpanzee tool assemblages recovered at ant nests over a 41 month period between May and September Further details on tools used in gathering ants by this chimpanzee population can be found in [ 64 ].

Tool use in honey gathering was recorded opportunistically during daily reconnaissance surveys in the study area.

The dataset for this study was collected between September and March Because honey gathering is a relatively rare behaviour, our analysis represents all individuals observed each month during the study period. Instantaneous min group scans of party composition and behaviour were recorded during all chimpanzee encounters between January and August Chimpanzee parties were considered to be all individuals travelling, feeding, resting or socializing within 50 m of one another definition adopted from [ 65 , 66 ].

In addition to noting the number of individuals present in the party, the basic activity patterns of all individuals were recorded at each scan interval. A total of 11 party scans were recorded during the study period, of which involved feeding observations. The proportion of scans with observations of fruit and leaf feeding was compiled for each month of the study period.

Relative abundance of preferred chimpanzee foods was systematically assessed through establishment of two trail networks to monitor the phenological states of tree species and strangler figs known to be consumed by this ape population [ 67 ]. A total of trees representing 47 species were monitored each month in the Goualougo Triangle. The crown of each monitored tree was visually examined to determine the abundance of fruit unripe, ripe , leaves old, new and flowers.

Relative abundance of fruit was estimated on a scale of 0—4, with higher scores indicating more fruit. Similarly, abundance of flowers and leaves new and mature were rated on a scale of 0—4. Stationary rain gauges and thermometers with minimum and maximum temperature gauges were stationed in the Goualougo Triangle and Mbeli Bai base camps.

To assess the influence of climate on tool use, we calculated the total monthly rainfall, as well as monthly average minimum and maximum temperatures, throughout the study period in our analyses. Termite nest densities were estimated as part of systematic botanical surveys that were conducted throughout the Goualougo study area from to Our sampling effort included 42 plots. Botanical surveys were also conducted at termite nests to determine abundance of suitable tool materials in the environment.

All herbaceous and woody stems within 20 m of an active tool use site were identified and the distance from the tool site measured. Surveys were conducted at 10 termite nests. Multiple regression was used to examine the relationship between rainfall and fruit abundance over a period of 67 months, with the predictor being monthly rainfall and the response being the proportion of trees with ripe fruit.

Both variables were square root transformed to achieve approximately symmetrical distributions and fulfil the assumptions of normally distributed and homogeneous residuals assessed by visual inspection of residuals plotted against fitted values and qq-plot of residuals. Influential cases were no issue assessed by DF beta values and DF fits ; [ 68 ]. The predictor was z -transformed to a mean of zero and a standard deviation of unity.

Temporal autocorrelation was accounted for by explicitly taking it into the model. Specifically, we first ran the model as described above and derived the residuals from it. We then averaged, separately for each data point, the residuals of all other data points, whereby we weighted their contribution to this average by the time lag between the specific data point and the residual.

The weight function had the shape of a Gaussian distribution with a mean of zero i. To address concerns of the unit-sum constraint in our analysis of feeding ecology, we examined fruit and leaf feeding as percentages of the overall activity budget.

A negative binomial model was used to examine our data on chimpanzee feeding ecology which spanned 56 months, with the predictor being the proportion of fruit feeding scans square root transformed and the response representing leaf feeding scans. The total number of scans was controlled for by including it log-transformed as an offset term.

DF beta values revealed model instability to be no obvious issue. To facilitate comparisons with other studies that examine the importance of food parts as a subset of only feeding observations, we also report the number of fruit and leaf feeding scans as a subset of feeding observations. Total time spent gathering termites with tools was determined for each subject and then standardized per subject to a sum of unity. Linear models assuming normally distributed and homogeneous residuals were run for temperature, rainfall, flowering trees, fruiting trees and leaf abundance.

The autocorrelation term was evaluated for each model individually. To examine the relationship between ant gathering and chimpanzee food abundance, we used separate GLMs with negative binomial error structure for each of the three predictors of resource abundance flowering trees which was square root transformed, fruiting trees and abundance of leaves.

Autocorrelation was incorporated as in the other models. Total sample size was 26 months. A single GLM including both predictors with negative binomial error structure was used to examine the relationship between tool use in ant gathering and climatic variables. Rainfall was log-transformed. Sample size was 41 months. The frequency of honey gathering was assessed over a 40 month period using a GLM with negative binomial error structure. Autocorrelation was accounted for as in the other models.

All models were run in R [ 69 ], and negative binomial GLMs were run using the function glm. When we chose a negative binomial error structure, this was carried out, because the response was a count, but the assumption of no overdispersion as made by a Poisson regression was violated. The autocorrelation term was implemented using a function written by R. A short rainy season and a short dry season occur in the intervening months. A positive relationship between proportion of fruiting trees and rainfall was documented in northern Congo.

Based on phenological monitoring of chimpanzee food items, the period of highest fruit abundance was from April to September. The resource-scarce period can be characterized as October through March. Of the scan observations that contained feeding observations, chimpanzees spent an average of Chimpanzees consumed a higher proportion of leaves when preferred fruits were not available, as shown in the relationship between proportion of party scans in which the apes were observed feeding on leaves or fruits.

Similar to Suzuki et al. Rather than tracking seasonal abundance of termites, this chimpanzee population has developed two specialized tool sets to overcome the obstacles of access presented by epigeal characterized by earthen mounds or towers and subterranean termite nests. A tool set composed of a perforating twig, and a fishing probe was used to open the surface of epigeal nests and then extract termites [ 15 , 53 ].

At subterranean termite nests, chimpanzees used a puncturing tool to create a tunnel into the subterranean termite chambers and then used this tunnel to insert a fishing probe to extract the termites [ 15 , 53 ]. The epigeal nests of M. Some of the termite nests in the Goualougo Triangle study area have persisted for more than 10 years, and thus provide a predictable location where insects can be harvested and information about the tool using task gathered either indirectly from discarded tools or directly from observations of conspecifics visiting the same site.

Figure 9 a shows the close proximity of tool users in this context. As discussed in the following section, party size during termite fishing is smaller than in other foraging contexts but the social network depicts dense connectivity within the community [ 61 ]. Average time spent gathering termites with tools for 11 chimpanzees error bars show standard deviation in relation to the proportion of fruiting trees on the Goualougo Triangle phenology circuit.

However, the sound of pounding clubs against the target beehive entrance can be audibly detected and often visually observed, as here, from greater distances than typical terrestrial tool using sites. Photo credit: Ian Nichols. Online version in colour.

Chimpanzees used a tool set composed of a perforating twig and a dipping wand to gather ants throughout the year. Annual profile of tools used in dipping for ants and perforating ant nests error bars show standard deviation. Tool use in honey gathering occurred throughout the year, but the low frequency of occurrence precluded analysis at the individual level.

Although not evident within single years, overall patterns of honey gathering roughly coincided with the flowering of trees when observations were pooled over the entire study period figure 8.

A slight discordance between peak flowering events and tool use is expected due to the delay in honey production by bees. Estimates of beehive abundance are not available from the study site, but suitable tool materials are readily available as the tools are most often fashioned from branches in the same tree canopy where the beehive is located.

Honey gathering has been most often observed when individuals are alone or with their dependent offspring [ 61 ], but the sound of pounding clubs against the hive entrance can be detected from distances greater than 50 m that could stimulate interest among individuals in nearby parties.

The arboreal setting also increases the distance that the tool user is visible compared with most terrestrial tool using settings figure 9 b , but may not provide adequate substrate for conspecifics to gather in close proximity to the tool user. Annual profile of chimpanzee tool use in honey gathering in comparison to relative flower abundance.

Honey gathering is presented as average number of observations per year error bars show standard deviation. Flower abundance is represented by the proportion of flowering trees on the Goualougo Triangle phenology circuit. When resource scarcity is extreme, the fission—fusion social structure of chimpanzee societies enables them to flexibly respond by reducing the size of their parties.

Foraging parties were largest when chimpanzees were feeding on fruits, flowers and leaves [ 61 ]. Foraging subgroups at termite nests were relatively small 2. Indirect social input from conspecifics included discarded tools and changes to the substrate at tool using sites. In the Goualougo Triangle, an average of 3.

Honey gathering typically occurs in the forest canopy. Resource abundance and distribution can influence tolerance of individuals at a feeding site.

Termite nests are located throughout the Goualougo Triangle study area, at densities which provide multiple tool using opportunities within the home range of any individual.

This may explain why the average number of individuals in chimpanzee parties at termite nests is typically smaller than parties foraging on other resources [ 61 ]. Such social gatherings provide information about the location of target prey and link tool-assisted foraging strategies to those targets.

In this study, we examined possible ecological and social correlates of the diverse and complex tool using behaviour exhibited by a chimpanzee population residing in central Africa. First, we determined whether technical skills provided access to fallback food resources when preferred food items were scarce.

Fruits are the preferred food item of these chimpanzees and their relative abundance fluctuated seasonally in the Goualougo Triangle study area. During times of relatively low fruit abundance, the chimpanzees increased their consumption of leaves, which fit the traditional definition of fallback foods, being highly abundant and of relatively poor nutritional quality [ 8 ]. However, variation in the abundance and nutritional quality of different leaf resources consumed by apes should be more specifically examined.

The Goualougo chimpanzee population did not seem to compensate for the lack of fruit resources by increasing their frequency of tool use for social insects or honey. Further, our review of studies that have explored the ecological dimension of the presence or absence of technology clearly shows that necessity may play a less prominent role in prompting and promoting tool using behaviours than previously suggested table 1.

We did show that opportunities to gather termites, ants and honey were available throughout the year and enhanced by the use of tool sets. Ant dipping was related to rainfall, and honey gathering showed some coincidence with patterns of tree flowering which precedes the peak periods of honey production. Rather than use tools to harvest fallback resources in response to seasonal fluctuations in preferred food resources, our conclusion is that these chimpanzees used their technical skills to maintain year-round access to embedded food items.

In addition to ecological drivers, social factors are also likely to play a role in the invention and maintenance of complex tool using behaviours. Party size was consistent throughout the year and relatively small in tool using contexts within the Goualougo Triangle, which prompts further examination of social tolerance and specific types of social interaction on the evolution of technological traditions [ 13 , 73 , 74 ]. To compensate for scarcity of preferred resources, fallback foods must provide a major source of energy and be consumed at a degree that effectively replaces the nutrients provided by preferred food items.

This seems feasible in the case of pestle pounding of oil palms and cracking of nuts among chimpanzees of Bossou in Guinea [ 31 ] and the nut cracking of Tai chimpanzees in Ivory Coast [ 33 ]. Although the food items harvested with tools are a rich source of nutrients, they comprise a relatively small component of the diet of the nut cracking capuchins at Fazenda Boa Vista in Brazil [ 44 ] and insect harvesting orangutans at Suaq Balimbing in Sumatra [ 29 ].

Chimpanzees at both Gombe in Tanzania and Fongoli in Senegal allocated significant foraging time to harvesting Macrotermes during particular months [ 35 ].

Termites can be a significant source of several important nutrients, including manganese, protein and amino acids [ 46 , 75 ], and are considered an important food in the Fongoli chimpanzee diet [ 35 ]. However, social insects do not fit the typical profile of fallback food resources [ 8 ]. While army ants may provide additional protein and micronutrients when they are consumed by chimpanzees, Koops et al.

It was reported that the nutritional value of arboreal ants harvested with tools at Mahale appears to be negligible [ 40 ]. The amount of honey gathered from stingless bees Trigona spp. The primary nutritional benefit of honey gathering is carbohydrates primarily fructose, glucose and about 25 different oligosaccharides [ 76 ].

Honey also contains small amounts of proteins, enzymes, amino acids, minerals, vitamins and polyphenols [ 76 ]. Further research is required to evaluate if foods gathered with the aid of tools provide sufficient nutrition to serve as fallback foods or are indeed energetically more profitable than other food types. Chimpanzees, macaques and capuchins are some of the most versatile primate species with regard to their ability to survive in different habitat types.

Some habitats in which these primates live may not offer traditional fallback foods, and so primates are prompted to procure higher quality resources when their staple food items are scarce. This could be the case with the seafood harvesting macaques on islands in the Andaman Sea [ 77 ] or the termite harvesting chimpanzees of Fongoli in Senegal [ 35 , 78 ].

Further, tool use may also be necessitated in localities where feeding competition within or between species is high [ 26 ]. Interspecific feeding competition could result in decreased abundance of particular foods through direct or scramble competition. Patterns of food consumption by other species could also mask or amplify seasonal patterns of food resource abundance. Interspecific competition could be elevated in central Africa where chimpanzees coexist with gorillas and other primates [ 79 ].

While segregated foraging and utilization of specialized feeding strategies are the typical coping mechanism of sympatric species that show a high degree of dietary overlap [ 80 , 81 ], another option would be the diversification or intensification of tool using strategies [ 16 , 82 ]. Reduced risk of predation is another ecological factor which could be associated with the evolution of tool use through reduced mortality which favours evolution of life histories that are more conducive to cognitive adaptations.

Reduced predation may also relax anti-predator vigilance and associated behaviours which could then liberate more time for object interaction and exploratory behaviours [ 22 ].

Changing ecological circumstances may also influence the emergence of tool use. Recent shifts in habitats caused by conversion or degradation may cause apes to increase the frequency of some particular types of tool use to compensate for missing resources.

Pestle pounding tool use occurs in the canopy of oil palm trees Elaeis guineensis and so is limited by the distribution of this species, which is closely associated with human cultivation [ 26 ]. Think about some of the tools you use every day. Are there tools we as humans use that are similar to those used by chimpanzees? Most of the tools that chimps make and use are actually geared towards eating.

Just as human cultures use different utensils for food, so do different groups of chimps. Think about the utensils we humans use to eat our food. In Asian countries it is usual for chopsticks to be used, while in America forks and knives are common utensils.

What do you eat with at your house? We and chimpanzees are both very similar in the ways we use and create tools for our benefit. Jane Goodall first discovered chimpanzees using tools to capture termites, which were buried underground in sealed mounds of dirt called termite mounds.

She noticed that they would use two different sticks as tools to acquire the protein rich insects. The first thing chimps do is use a heavy stick to chisel a hole into the termite mound to find an opening. The second tool they use is much more refined than their chisel. The second stick is known as a fishing tool and it is very special because they actually modify it before using it. The chimpanzees find a straight stick or long blade of grass and pull all of the leaves off of it, so that they can easily fit the stick into the hole of the termite mound.