Tag Archives: primates

Monkey See, Monkey Do

Cognition, learning, and evolution in human and non-human primates

Primate Social Cognition, Human Evolution, and Niche Construction
Evolution of a student

The old image of a human evolving from an ape by gradually getting more upright is a common way to portray the concept of evolution, even though the imagery portrays a slightly incorrect concept: humans did not evolve “from apes,” modern day humans and modern day non-human primates evolved from a common ancestor. While this distinction may seem semantic, it’s important to note because the study of modern non-human primates is not quite exactly the same as peering back into our own evolutionary history. It can, however, still offer incredible insights into the overall evolution of our species, especially when it comes to cognition and learning, and offers clues as to how our species’ brain evolved the way it did. That is, studying cognition across the Primate order can provide a framework for understanding cognitive functioning and evolution.

One of the key commonalities all primates share is a dependence on close social relationships for support with security, food resources, and child rearing (MacKinnon and Fuentes 2012). Living in stable social groups allowed early primates to be able to deal with threats more efficiently. This lead to changes in the environment, such as, among other things, predators deciding to go after other pray. As threats lessened as a result of the adaptation of social groups, primates were then able to spend more time and energy in building social relationships, exploring territory, and experimenting with different foraging strategies (MacKinnon and Fuentes 2012). All of this lead to primates both requiring and having the opportunity to increase cognitive functioning. In this way, primates shaped their environment and were in turn shaped by the changing environment. This concept is called niche construction—primates created a niche for themselves in their environment that shaped both the environment and their evolution. This concept illuminates some of the intricacies involved in understanding evolution: the model of organisms merely adapting to their environments for the purpose of survival doesn’t quite capture the complexity involved.

Human niche construction and evolution, specifically, depended upon an increasingly sophisticated way of interacting with the environment. With the use of more tools, better survivability rates for infants, and increasingly complex methods of communication, early humans were able to efficiently increase their territory and cooperate within and among groups. The success of these adaptations meant more resources, and the conditions were fertile for the evolution of human cognition.

This chapter gives a good, easy to understand overview of the evolution of primate cognition, and makes a good case for the purpose of studying primate cognition in neuroanthropology. Of course, as an overview it ends up lacking in some specificity of the concepts covered, but the following articles address some of the more important areas more in-depth.

Understanding Primate Brain Evolution

The increasingly social nature of primates, as well as the increasing complexity of interactions with the environment, lead to an increase in the types of interactions and concepts that needed to be exchanged. To put it another way, the complexity of interactions increased. This is the basic idea behind the social brain hypothesis, which says that brain size, specifically the neocortex, is correlated with not just group size but the complexity of relationships within a social group (Dunbar and Shultz 2007). Some examples of complex social interactions necessary for survival in large groups that primates exhibit that require higher cognitive functioning include tactical deception, social play, and the use of subtle social strategies (Dunbar and Shultz 2007). The increase in neocortex size does not come without some tradeoffs, however: diet, infant care, and development have all shifted to account for the change in brain size necessitated by and necessary for increasingly complex social interactions.

This article is a thorough examination of the variables at stake in understanding the evolution of primate cognition. However, the statistical analyses and language used make it unapproachable for a casual reader. The previous piece covers the subject material in a more approachable way, though certainly doesn’t go into the depth of what’s involved in the social brain hypothesis.

Play, Social Learning, and Teaching

Complex social interactions like the ones required for primate survival, and that lead to the evolved human brain, needed to have been passed down from generation to generation in order to be evolutionary. One primary way learning of this kind takes place is through social play. Play is, in terms of survival, both costly and risky, which means that it likely has significant adaptive value (Konner 2010). As it turns out, the smartest animals are the ones that play the most, and it’s likely these two things co-evolved (Konner 2010). Interestingly, while the size of the neocortex is associated with intelligence and social complexity, the capacity for play appears to be housed in the limbic system, an older and more primitive part of the brain; however, animals with larger brains do play more and the animals with the largest brains play the most (Konner 2010), perhaps reflecting the increased complexity of the learning that needs to occur. For more information on the regions of the brain, see Kalat (2012).

While the process is not fully understood, social learning, unlike basic learning processes, likely takes place due imitative learning, assisted by the mirror-neuron system (MNS; Konner 2010). The MNS activates not only when one observes an action, but also right before an action is taken, which suggests that there is a link to the ability to perceive the intentions of others (Konner 2010).

This chapter comes from a book on childhood and development, so this chapter on social play doesn’t quite go into the specific depth that we might be interested in as neuroanthropologists, especially the neurobiology of social learning. While the mirror-neuron system is interesting and an exciting step toward understanding, its treatment is rather shallow and other systems aren’t included in the explanation.

Primate Cognition

While the above articles explain in varying degrees of accessibility the arguments for the evolutionary path of human cognition, they don’t go into much detail about the cognitive capabilities of our primate ancestors. Understanding the extent of primate cognition could help to understand the capabilities that primates had, prehistorically, that could contribute to and be shaped by their social complexity. According to Beran et al. (2016), controlled attention, episodic and prospective memory, metacognition, and delay of gratification have all been observed in chimpanzees. Non-human primates don’t match the cognitive abilities of humans in these areas, but their presence sheds light on the potential cognitive capabilities of our primate ancestors. Of course, it needs to be kept in mind that their study was done in a controlled laboratory setting with a modern chimpanzee, so the results would be different than a wild primate ancestor.

The scope of research included in this paper is impressive. Each component of cognition is tested well, with good results. While it is a psychology-oriented paper, more discussion of the implications for the understanding of primate evolution would have been welcome. Additionally, there isn’t any discussion of how these cognitive capabilities would be expressed in natural settings.

Questions for consideration:

What is niche construction, and how does it relate to our understanding of evolution? Can you think of any other examples of it?

What is the social brain hypothesis, and how does it relate to the evolution of the brain? What lines of evidence do we have that support this hypothesis?

How do modern advancements in technology alter the way we think about “play” as it relates to social learning?

What do you think about the understanding of gender in play relationships described in Konner’s article?

Resources:

Beran, Michael J., Charles R. Menzel, Audrey E. Parrish, et al.
2016   Primate Cognition: Attention, Episodic Memory, Prospective Memory, Self-Control, and Metacognition as Examples of Cognitive Control in Nonhuman Primates. Wiley Interdisciplinary Reviews: Cognitive Science 7(5): 294–316.

Dunbar, R.I.M, and S. Shultz
2007   Understanding Primate Brain Evolution. Philosophical Transactions of the Royal Society B: Biological Sciences 362(1480): 649–658.

Kalat, James W.
2012   Biological Psychology. Cengage Learning.

Konner, Melvin
2010   The Evolution of Childhood: Relationships, Emotion, Mind. Harvard University Press.

Lende, Daniel H., and Greg Downey, eds.
2012   The Encultured Brain: An Introduction to Neuroanthropology. Cambridge, Mass: The MIT Press.

 

Evolving Brain Stuff, Y’all

The Authors: The article, entitled “Evolution of the Cerebellar Cortex: The Selective Expansion of Prefrontal-Projecting Cerebellar Lobules,” was researched and written by Dr. John Balsters, E. Cussans, Jörn Diedrichsen, Dr. Kathryn A. Phillips, Dr. Todd M. Preuss, Dr. James K. Rilling, and Dr. Narender Ramnani. All of these people have interests in the cerebellum and motor functions.

 

Hypothesis: The authors predicted that since the prefrontal cortex has evolved to be larger in relation to the motor cortex in humans, there should also be enlargements in the cerebellum, specifically those parts that are associated with the prefrontal cortex, in relation to the lobules of the cerebellum associated with the motor cortex.

 

This shows where the cerebellum is located. The prefrontal cortex is located at the front of the cerebrum and the motor cortex in about the middle of the cerebrum.

 

The Experiment: They decided to test their hypothesis by examining three different primate species, humans, chimpanzees, and capuchin monkeys.  They took ten different subjects for each species, five of these were males and five were females.  All of the subjects were of an age where the brain would have reached full maturity.  High-resolution MRI scans were taken of each of the subject’s brains, as well as structural images. Using various programs, the scans and images were oriented in the same direction, and the cerebellum was eventually isolated from the rest of the brain, so that the scientists were left with only images of the part of the brain they were interested in (those lobules that were associated with the motor loop or the prefrontal loop). They then extracted images for the cerebellar lobules using the FSLView program. The volumes of each of the images of the cerebellar lobules were then calculated. The specific parts of the cerebellum they isolated were Lobule V, Lobule VI, Crus I, Crus II, Lobule VIIb, and Lobule VIIIa. After completing the calculations of the volumes of the lobules, they decided to compare the volumes measured against the volume of the whole cerebellum and against the sum of the volumes that had been masked, which are those related to the motor and prefrontal cortex.

 

A capuchin monkey

 

Results: In reference to the lobules of the cerebellum when compared to the whole cerebellum, the largest differences across the species came from the comparisons with Crus I and Crus II, in which humans were found to have the greatest proportion, followed by chimpanzees and then the capuchin monkeys.

A chimpanzee

 

In reference to the lobules of the cerebellum when compared to the masked volumes, it was found that the volumes of the masked lobules occupied the greatest portion of the cerebellum in humans, followed by chimpanzees and then capuchin monkeys respectively. Through this comparison, it was again shown that the greatest differences between species came from the Crus I and Crus II sections.

 

Difference in size of a human brain (left) and a chimpanzee brain (right).

Discussion: They have shown that the evolution of the cortical lobules is directly related to the evolution of the neocortical areas that are associated with them. Crus I and Crus II specifically are much larger than other lobules associated with the primary motor cortex. It was also discovered that Crus I and Crus II in capuchin monkeys are significantly smaller than Crus I and Crus II in humans and chimpanzees. The enlargements in the cerebellar cortex relate to those of the prefrontal cortex in all of the species. These enlargements in the human brain correlate specifically to its functional specializations.

The scientists compare their data to that of the brains of Old World monkeys and hypothesize that the volumes of Old World monkeys should fall in between those of the chimpanzees and the capuchin monkeys, which upon further examination proves to be accurate in the observation of one macaque monkey.

The allometric trends that could arise due to these differences between the species are an area the scientists think needs more study and that they did not examine specifically.  They do, however, state that humans definitely depart from the isometric trends, which they attribute to the differences in the cerebellum.

The enlargement of the prefrontal cortex in humans had been attributed to white matter expansions as opposed to grey matter.  This study suggests the opposite. It is mentioned that the cerebellum is largely made of white matter, but the lobules that were examined in this study were largely comprised of grey matter, which is the reason for the shift.

 

My comments: I found this article to be incredibly difficult to understand, which was surprising to me because I do not usually find myself struggling to read articles about research experiments.  That being said, research articles such as this are very often written with a specific audience in mind and are therefore fairly exclusionary to the general public. The problem with this is that laymen can not find materials to read on subjects like this because they are largely unreadable to the public. It can cause a lot of misunderstanding or loss of interest in subjects such as this because most people will not usually try to wrestle with and understand much of the scientific jargon used in the article.