The ability to learn patterns, ultimately the rules of language has rarely been studied in new world primates. In this study the researchers use species specific sounds/tones to determine if the squirrel monkeys were able to decipher when the correct order and incorrect order of these sounds were played. This is the first study that has used species specific frequencies in order to test their abilities. Other studies relied on humans producing syllables, which may not have been the most appropriate way to measure the monkeys’ capabilities.

Two ordered sound patterns were tested with the same rule being applied of A Bⁿ A.

Test 1 – Low Tone= A, and High Tone = B (eg. Low, High, High, High, Low)

Test 2 – High Tone = A and Low Tone = B (eg. High, Low, Low, High)

The results suggest that the monkeys were able to consistently decipher when the rules were being broken in both the test settings.

These finding suggests that the ancestor of both squirrel monkeys and humans which existed approximately 36 million years ago would also have been able to understand the rules involved in pattern learning, thus most living apes and monkeys today should also be able to do this. This skill may have evolved as a cognitive ability rather than a direct pre-cursor to language.

Ravignani, A., Sonnweber, RS., Stobbe, N. and Fitch, TW (2013). Action at a distance: dependency sensitivity in a New World primate. Biology Letters. 9. 20130852

Ruth Sonnweber, one of the scientists from this study is now continuing similar work here with our squirrel monkeys in Living Links, however instead of sound stimuli she has been using touch screen to determine their ability to learn patterns.

Chimpanzee Alarm Call Production Meets Key Criteria for Intentionality

Determining the intentionality of primate communication is vital to understanding the evolution of human language. Although intentional signalling has been studied for some great ape gestures, comparable evidence is currently lacking for their vocal signals.

In this study the following criteria were used to analyse if the Sonso group of chimpanzees in the Budongo Forest in Uganda were communicating with intention.

The researchers presented the chimpanzees with a python model with up to 4 observers recording the calls and behaviours of each focal individual.

Figure – The snake image represents the location of the python
model, concealed by leaves. Observers and their main roles are defined. The
chimpanzee image depicts the focal chimpanzee, who could be accompanied by
other group members depending on the experimental condition.

The results of this study indicate that some chimpanzee calls meet the criteria for intentionality, for example most chimpanzees who had seen the snake model gave calls and demonstrated gaze alternation and audience checking with a fellow chimpanzee. ‘Waa Barks’ (WB) and ‘Alarm Huus’(AH) were produced in the presence of socially important individuals who had not seen the snake. Furthermore , WB’s and AH’s were increased in the presence of friends vs. non-friends.

The researchers believe that their findings disagree with the gestural theories of language origins and instead support a multimodal origin for human language.

Video illustrating gaze alternation and looking at a group member before producing waa barks. Video is filmed from position 2. Focal adult female Nambi reacts to the arrival of her adult son Musa by turning and looking at Musa before producing her first waa barks of the trial. Nambi then looks immediately back at the snake, showing gaze alternation between the recipient and the snake whilst calling. During Nambi’s waa bark production, Musa stands bipedally.

Schel, AM., Townsend,SW.,Machanda, Z.,Zuberbuhler, K., and Slocombe, KE. (2013). Chimpanzee Alarm Call Production Meets Key Criteria for Intentionality. PLoS ONE 8 (10): DOI: 10.1371/journal.pone.0076674

Social networks shape monkey “culture”

A new study, published in Current Biology, shows that squirrel monkeys who are at the heart of their social group pick up innovations first, and are more likely to acquire new cultural variations in behaviour like novel foraging techniques.

Dr Nicolas Claidière, Ms Emily Messer and Professor Andrew Whiten of the University of St Andrews in collaboration with Dr Will Hoppitt of Anglia Ruskin University studied both our East and West squirrel monkeys. They examined their social networks by recording who spent time with whom when the monkeys were in the vicinity of an “artificial fruit” that could be used to obtain food rewards by using two different techniques, lift or pivot (Figure 1).

Sophisticated statistical analysis of this information revealed the details of the monkeys’ social networks which helped the researchers visualize which monkeys were at the heart of the network and which were more peripheral (Figure 2). Each monkey was rated on a measure of their ‘centrality’ within the group.

Boa the alpha male in the East group was briefly separated and trained how to use the lift technique and his equivalent, Rio in the West group was trained to use the pivot technique, they were then reunited with their respective groups.

The scientists found that monkeys who were well-connected were the most likely to successfully pick up the new technique seeded in their group. They were also more likely to acquire the lift technique in the group seeded with ‘lift’, versus the pivot technique in the group seeded with ‘pivot’, so the alpha males were truly the hubs of these two different monkey ‘cultures’.

Professor Whiten, from the University of St Andrews, said: “Our study shows that innovations do not just spread randomly in primate groups, but as in humans, are shaped by the monkeys’ social networks”.

Dr Claidiere said: “Research interest in social learning and social network analysis has surged in recent years, and our results are likely to stimulate further research on the spread of innovations in animal social networks.

“We suspect that our focus on a social network relevant to the diffusion of foraging innovations can explain why we found an effect of the network centrality of individuals on their learning.

“Previous research has focused on other relationships, like who grooms whom, which may not correlate with the monkeys’ observational learning in the same way”.

Emily Messer, noted another aspect of the study. “We also found that maternal relationships explained parts of the social network, so some of the diffusion of the new foraging habits were also probably reflecting an emphasis on learning within families,” she said.

Click here to lead you to the abstract of the article in Current Biology