Just over a decade ago, an evolutionary psychologist conducted a fascinating study centered around people’s Christmas card lists. This tradition of sending Christmas cards offers intriguing insights into a fundamental aspect of human evolution: the social brain. The social brain hypothesis proposes that human intelligence evolved primarily to manage the complexities of our social interactions.
Our behaviors are intricate, and the more information we need to process about our surroundings, the greater our cognitive capacity must be. Notably, the neocortex, a part of our brain, is linked to the size of our social groups. The neocortex, the brain’s outer layer, is responsible for higher-order functions such as conscious thought, language, and spatial reasoning.
Researchers have studied the neocortex of various primates, comparing its size relative to the rest of their brains, and discovered a pattern. For instance, lemurs with smaller neocortexes live in social groups of about nine, while long-nosed monkeys with larger neocortexes live in groups of around 14. The Western Red Colobus monkey, with a slightly larger neocortex, forms groups of 35, and chimpanzees, possessing the largest neocortex among primates except humans, live in groups of about 53.
Applying this pattern to humans is challenging, as we don’t all live in local groups or engage in grooming behaviors typical of other primates. This is where the Christmas card study becomes relevant. Participants were asked about the number of people they sent cards to, their proximity, the last time they communicated, and their emotional closeness to these individuals. The study found that the average number of cards sent was 68, leading to an estimated average social network size of 153 people.
Despite its insights, the study has limitations. People might send cards for political reasons or vary in their approach to creating Christmas card lists, depending on their cultural practices. The psychologist behind this study, Robin Dunbar, has a number named after him: the Dunbar number. This number, around 150, represents the maximum number of meaningful relationships one can maintain, based on the neocortex ratio applied to humans.
This number aligns with group sizes in Neolithic farming villages and Roman military units. Given our neocortex’s limited capacity, maintaining more relationships can be challenging. However, comparing a Neolithic village to today’s world is like comparing the present to the Stone Age. So, what does the Dunbar number signify today, and is it evolving?
In our era of expanding social networks, even if you have 300 Facebook friends or a thousand Instagram followers, time remains a constraint in nurturing friendships. While status updates or photo posts are efficient, they lack the personal touch of direct communication. Research indicates that face-to-face interaction is crucial for sustaining quality relationships. Being physically close to friends and loved ones triggers the release of endorphins and higher levels of oxytocin, vital for social bonding.
Although our neocortexes are limited in size, our brains are remarkably adaptable, capable of growing and adjusting to our environments. It’s possible that today’s children will develop different neural organizations to handle evolving social interactions. Research on this topic is ongoing, and by the time we have more answers, traditions like sending Christmas cards might become relics of the past.
Reflect on your own social network by listing the people you regularly interact with. Categorize them based on the frequency and depth of your interactions. Compare your findings with the Dunbar number and discuss whether your network size aligns with the concept. Consider factors that might influence your network size, such as cultural background or personal preferences.
Participate in a class debate on the relevance of the Dunbar number in the context of modern digital communication. Form teams to argue for or against the idea that the Dunbar number is still applicable in today’s world of social media and virtual interactions. Use evidence from the article and additional research to support your arguments.
Conduct a research project on the social brain hypothesis. Investigate how the neocortex size correlates with social group sizes in different species, including humans. Present your findings in a report or presentation, highlighting any new insights or questions that arise from your research. Consider how this hypothesis might apply to future human social structures.
Design and conduct an experiment to compare the effects of face-to-face communication with digital communication on relationship quality. Gather a group of participants and have them interact with friends or family members through both methods over a set period. Analyze the results to determine which method fosters stronger social bonds and discuss the implications for maintaining relationships in the digital age.
Write a short story imagining a day in the life of a person living in a Neolithic village with a social group size similar to the Dunbar number. Explore how social interactions and relationships might differ from today’s world. Consider the role of face-to-face communication and the absence of digital technology in shaping social bonds and community life.
Here’s a sanitized version of the provided YouTube transcript:
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[Music] Just over 10 years ago, an evolutionary psychologist designed a study investigating people’s Christmas card lists. The tradition of sending Christmas cards is an interesting behavior that gives us clues about one of the things that defines us as human throughout evolution: the social brain. The social brain hypothesis suggests that human intelligence evolved to navigate our complex social groups.
We have these intricate behaviors, and the more information we need to store and manipulate about our environment, the larger our cognitive capacity needs to be. What’s particularly interesting is that one part of our brain, the neocortex, is correlated with the size of our social groups. The neocortex is the outer layer of our brain and is responsible for higher functions like conscious thought, language, and spatial reasoning.
Researchers examined the neocortex of other primates and compared it as a ratio to the size of the rest of their brains, discovering a pattern. Lemurs with smaller neocortexes live in social groups of about nine, while long-nosed monkeys with a larger neocortex live in groups of around 14. The Western Red Colobus monkey, which has a slightly larger neocortex, lives in groups of 35, and chimpanzees, which have the largest neocortex of all primates except for humans, live in social groups of about 53.
Hypothetically, we could apply this pattern to humans, but since we don’t all live in local groups and don’t groom each other, it’s tricky to determine our social network sizes. This is where the Christmas card study comes in. Participants were asked how many people they were sending cards to, how far away they were, the last time they had been in touch, and how emotionally close they felt to those individuals. Researchers found that the average number of cards sent was 68, and since one card can be sent to multiple people, the average social network size was estimated to be 153 people.
However, the study has some limitations. People may send cards for political reasons as well as social ones, and individuals put varying amounts of thought into their Christmas card lists, depending on whether they celebrate Christmas or send cards at all. The psychologist who designed the Christmas card study, Robin Dunbar, is one of the few people who has a number named after him. The Dunbar number represents the limit of meaningful relationships that one person can maintain, estimated to be around 150 based on the neocortex ratio applied to humans.
This number is consistent with group sizes in Neolithic farming villages and armies in Roman antiquity. Since our neocortex has a limited capacity, it can be challenging for our brains to accommodate more relationships. However, considering the size of a Neolithic farming village is akin to comparing the present to the Stone Age. What does the Dunbar number mean today, and is it changing?
With ever-expanding social networks, even if you have 300 friends on Facebook or a thousand followers on Instagram, time is a limiting factor in maintaining friendships. While status updates or posting photos are efficient, they are not as personal as direct communication. Research suggests that we need face-to-face interaction to maintain quality relationships. Physical proximity to friends and loved ones leads to the release of more endorphins and higher levels of oxytocin, which are essential for social bonding.
While our neocortexes are limited in size, our brains exhibit remarkable plasticity, allowing them to grow and adapt to our environments. It is possible that children today will develop different neural organizations to manage changes in social interactions. Studying today’s children is still in progress, and by that time, traditions like this one could become relics of the past.
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This version removes any informal language and clarifies the content while maintaining the original meaning.
Friends – Individuals with whom one has a bond of mutual affection, typically exclusive of sexual or family relations, playing a crucial role in social and emotional development. – In psychology, friends are considered vital for emotional support and can significantly influence one’s mental health and well-being.
Social – Relating to society or its organization, often involving interactions and relationships among individuals or groups. – Social dynamics are a key area of study in sociology, as they help us understand how individuals behave in group settings.
Brain – The organ in humans and other animals that is the center of the nervous system, responsible for processing sensory information and regulating behavior. – Neuroscientists study how different areas of the brain are activated during various psychological tasks.
Neocortex – The part of the brain involved in higher-order brain functions such as sensory perception, cognition, and generation of motor commands. – The expansion of the neocortex in humans is associated with advanced cognitive abilities, including language and abstract thinking.
Relationships – The way in which two or more people or groups regard and behave toward each other, often studied in psychology and sociology to understand social bonds and interactions. – Healthy relationships are crucial for psychological well-being and can impact stress levels and overall life satisfaction.
Networks – Interconnected systems of people or things, often used in sociology to describe the social connections and interactions among individuals or groups. – Social networks can influence individual behavior and attitudes, as well as provide support and resources.
Interactions – Reciprocal actions or influences between people, often studied in psychology and sociology to understand communication and social behavior. – The study of interactions in group settings can reveal important insights into social hierarchies and group dynamics.
Psychology – The scientific study of the human mind and its functions, especially those affecting behavior in a given context. – Psychology examines various aspects of human behavior, including cognition, emotion, and social interactions.
Sociology – The study of the development, structure, and functioning of human society, including social relationships, institutions, and culture. – Sociology provides insights into how societal norms and values shape individual behavior and group dynamics.
Bonding – The process of forming a close personal relationship, often studied in psychology to understand attachment and emotional connections. – Bonding experiences in early childhood can have a lasting impact on an individual’s ability to form healthy relationships later in life.
