Recall dependent on language?

A new study has been published in Current Biology which offers evidence to suggest that monkeys have the capacity for both recognition and recall of simple shapes.

The study showed that rhesus monkeys can recall shapes from memory. This was shown using an experiment which had the monkeys reproduce shapes on a computer touch screen. These findings suggest that the memory of humans and old world monkeys may be more similar than we previously suspected.

Recall is separate and special in comparison to recognition as it shows an ability to remember and visualise things which are not present in the moment. This is an ability which is implicated in skills such as planning and imagining. This is also thought to enhance things like navigation and social behavior. In the past it has thought that an ability to recall none present items is dependent on language. This has been suggested in the past by prominent linguists such as Charles Hockett who thought that the ability of displacement was facilitated by language and was a driving force behind its evolution.

Because of a lack of demand for recall in the lives of monkeys they will not use their recollection skills very often in the wild. In the press release, Benjamin Basile, who lead the study said:

“Maybe it’s often just easier to recognize the monkey, the food, or the landmark in front of you. What we do know is that they do seem to have the ability to recall information in the lab.”

Experiments with humans have shown that recall and recognition require different types of memory. This has been difficult to show with other primates as recall tests are difficult to devise for monkeys because they can’t draw or talk.

The experiment used five rhesus monkeys who were trained on a recall test in which they had to reproduce a simple figure on a touch screen from memory. The shapes were made up of large pixels or boxes on a screen. The monkeys were shown these shapes and then, after a delay, were presented with part of the shape in a different location. The monkeys had to replicate the rest of the shape by touching where the other pixels should be.

The monkeys remembered less in recall than in recognition tests which is the same case in humans. However, the recall performance deteriorated more slowly over time. The monkeys were also able to transfer their ability to recall shapes to novel shapes as they were shown to be able to recall shapes which weren’t used in training.

This ability has probably been present since our last common ancestor with old world monkeys some 30 million years ago and is probably not facilitated by language.

The study hypothesises that:

“Recollection and familiarity likely evolved because they solved functionally incompatible problems. For example, familiarity does not support detailed memory for context, but it is quick and resistant to distraction. Recollection is slower and more vulnerable to distraction but supports a more detailed and flexible use of memory. Familiarity might better allow rapid responses to foods and predators under distracting conditions, whereas recollection might be necessary to access knowledge of distant food locations or past social interactions for planning future behavior.”


Benjamin M. Basile, Robert R. Hampton. Monkeys Recall and Reproduce Simple Shapes from MemoryCurrent Biology, 28 April 2011


Cultural Transmission observed in Whales

A new paper in Current Biology, published today has revealed that the songs of Humpbacked Whales are passed through the ocean by mechanisms of cultural transmission.

Cultural transmission is defined as the social learning of information or behaviours either over generations or via peers. It has been seen to occur in primates, cetaceans and birds.

Cultural transmission over generations, i.e. parent passing socially learnt traits to their offspring, is known as vertical transmission and cultural transmission via peers, unrelated individuals from within generations, is known as horizontal transmission. In humans, languages and memes are transmitted, learned and (in a lot of cases) evolved in this manner.

Male humpback whales have a repetitive and evolving ‘song’ which acts as a vocal sexual display. This song is highly repetitive and is used, by mechanisms of social sorting and attraction, to allow for sexual selection within the whale population. All males within a population are known to conform to the current version of the display (song type), and similarities have been seen to exist among the songs of populations within an ocean basin.

The study being discussed presents very strong evidence for patterns of horizontal transmission, whereby song types spread unidirectionally and rapidly in the pacific ocean eastward through populations in the western and central South Pacific. The study was done over an 11-year period. This is the first documentation of a repeated, dynamic cultural evolution occurring across multiple populations at such a large geographic scale and across such a large time scale.

The patterns of cultural transmission seen in these whales songs are analogous to the same mechanisms we see in humans given that the songs are subject to mistakes and changes which are replicated. This causes the same mechanisms we see in the cultural transmission of language. The authors note that the level and rate of change seen in the whales is unparalleled in any other nonhuman animal and involves culturally driven change at a vast scale.

They also state that:

Investigating the underlying mechanisms of song evolution may yield powerful insights into the transmission of cultural traits and the evolution of culture and plasticity in sexually selected traits.

They also observed that at least one of the song types was transmitted between two different ocean basins, the Indian and South Pacific Ocean. It’s amazing to think how far a single song type can be horizontally transmitted.

Humpback whale song is unique among the animal kingdom due to the conformity to the current norm. This is coupled with high plasticity in the trait (ability to change their song based on whatever the new ‘norm’ is). Why both plasticity and conformity might be selected, how these interact with sexual selection, and how cultural evolution influences both are intriguing questions in need of consideration.


Garland, E. C.; Goldizen, A. W.; Rekdahl, M. L.; Constantine, R.; Garrigue, C.; Hauser, N.; Poole, M. M.; Robbins, J.; Noad, M. J. (2011) Dynamic Horizontal Cultural Transmission of Humpback Whale Song at the Ocean Basin Scale. Current biology : CB doi:10.1016/j.cub.2011.03.019

What Makes Humans Unique ?(III): Self-Domestication, Social Cognition, and Physical Cognition

ResearchBlogging.orgIn my last post I summed up some proposals for what (among other things) makes human cognition unique. But one thing that we should bear in mind, I think, is that our cognitive style may more be something of an idiosyncrasy due to a highly specific cognitive specialization instead of a definitive quantitative and qualitative advance over other styles of animal cognition. In this post I will look at studies which further point in that direction.

Chimpanzees, for example, beat humans at certain memory tasks  (Inoue & Matsuzawa 2007) and behave more rational in reward situations (Jensen et al. 2007).

In addition, it has been shown that in tasks in the social domain, which are generally assumed to be cognitively complex, domesticated animals such as dogs and goats (Kaminski et al. 2005) fare similarly well or even outperform chimpanzees.

Social Cognition and Self-Domestication

It is entirely possible that the first signs of human uniqueness where at first simply side-effects our self-domesticating lifestyle – the same way the evolution of social intelligence in dogs and goats is hypothesised to have come about –, acting on a complex primate brain (Hare & Tomasello 2005).

This line of reasoning is also supported by domesticated silver foxes which have been bred for tameness over a time period of 50 years but developed other interesting characteristics as a by-product: To quote from an excellent post on the topic over at a Blog Around the Clock (see also here):

“They started having splotched and piebald coloration of  their coats, floppy ears, white tips of their tails and paws. Their body proportions changed. They started barking. They improved on their performance in cognitive experiments. They started breeding earlier in spring, and many of them started breeding twice a year.”

What seems most interesting to me, however, is another by-product of their experimental domestication: they also improved in the domain of social cognition. For example, like dogs, they are able to understand human communicative gestures like pointing. This is all the more striking because, as mentioned above, chimpanzees do not understand human communicative gestures like  helpful  pointing. Neither do wolves or non-domesticated silver foxes (Hare et al. 2005).

Continue reading “What Makes Humans Unique ?(III): Self-Domestication, Social Cognition, and Physical Cognition”

Some Links #2

This week we all get to learn a new word, the potential origins of the written word and killing at a distance. Enjoy!