Chapter 3 The Bases of Human Behaviour

Introduction

Human beings are the most developed species on Earth, distinguished by our ability to walk upright, our large brain size relative to our body weight, and our capacity for complex cognitive behaviours like thought, language, and problem-solving. This chapter explores the foundations of these complex human behaviours.

Scientists study the relationship between our behaviour and the underlying biological systems, particularly the brain and the nervous system. However, behaviour is not shaped by biology alone. It is also profoundly influenced by our environment, especially the cultural context in which we are raised. This chapter will examine both the biological and cultural roots of human behaviour, providing an integrated understanding of how these forces interact to make us who we are. We will explore the nervous system, the endocrine system, and the role of genetics, as well as the processes of enculturation, socialisation, and acculturation that shape us as cultural beings.

Evolutionary Perspective

The diversity of life on Earth is the result of evolution, which refers to the gradual and orderly biological changes that occur in a species over generations in response to changing environmental demands. This process happens through natural selection.

• Natural Selection: Within any species, individuals vary in their traits. Those traits that increase an organism's chances of survival and reproduction are more likely to be passed on to the next generation. Over time, this leads to the evolution of species that are better adapted to their environment.
• Fitness: In evolutionary terms, fitness is defined as an organism's ability to survive and successfully pass its genes on to the next generation.

Modern humans (homo sapiens) evolved some 2,00,000 years ago. Three key features distinguish us from our ancestors and have been crucial for our development:

1. A larger, more developed brain, which supports complex cognitive abilities like reasoning, memory, and language.
2. The ability to walk upright on two legs (bipedalism).
3. A free hand with a workable opposing thumb, allowing for the precise manipulation of objects and the creation of tools.

Our highly complex behaviours are a direct result of our highly developed brain, which makes up about 2.35% of our total body weight—the highest ratio among all species.

Biological and Cultural Roots

Human behaviour is a product of the constant interplay between our biological inheritance and our cultural environment.

• Biological Roots: We inherit a developed body and brain from our ancestors. The importance of this biological foundation is evident in cases where brain damage from disease or injury leads to severe physical and behavioural disabilities. Our genetic makeup provides the blueprint for our development.
• Cultural Roots: As social beings, we are born into and shaped by a specific culture. Culture provides us with a framework of experiences, learning opportunities, and social demands that significantly influence our behaviour. This influence becomes more prominent as we grow and develop.

Therefore, to fully understand human behaviour, we must consider both its biological and cultural bases.

Biological Basis of Behaviour

Neurons

The neuron is the fundamental building block of our nervous system. It is a specialized cell with the unique ability to receive, process, and transmit information in the form of electrochemical signals.

Structure of a Neuron:

• Soma (Cell Body): The main body of the neuron, which contains the nucleus and other essential cell structures.
• Dendrites: Branch-like extensions that act as the "receiving ends" of the neuron. They receive signals from other neurons or from sense organs.
• Axon: A long, tube-like structure that transmits the neural impulse away from the soma towards other neurons, muscles, or glands.
• Terminal Buttons: Small structures at the end of the axon that release chemical messengers to transmit the signal to the next neuron.

Nerve Impulse:

Information travels through the nervous system as a nerve impulse. When a neuron is stimulated, it generates a sudden electrical change. This impulse works on an "all or none principle"—the neuron either fires completely or not at all. The strength of the initial stimulus does not change the strength of the impulse as it travels along the axon.

The Synapse:

Neurons are not physically connected. There is a tiny gap between the terminal button of one neuron and the dendrite of the next, known as the synaptic cleft. To cross this gap, the electrical impulse is converted into a chemical signal. The terminal button releases chemical substances called neurotransmitters, which travel across the synapse and stimulate the next neuron, thereby transmitting the information.

Structure and Functions of Nervous System and Endocrine System and Their Relationship with Behaviour and Experience

The Nervous System

The human nervous system is an intricate network that controls and coordinates all bodily functions and behaviours. It can be broadly divided into two main parts.

1. The Central Nervous System (CNS): The command center of the body, comprising the brain and the spinal cord.

The Brain: The brain is organized into three major parts:

The Spinal Cord: A long bundle of nerve fibers running through the spine. Its main functions are to transmit sensory and motor signals between the brain and the rest of the body, and to control simple reflex actions.

2. The Peripheral Nervous System (PNS): Composed of all the nerves that connect the CNS to the rest of the body.

• Somatic Nervous System: Controls voluntary actions, such as moving your muscles to walk or wave.
• Autonomic Nervous System (ANS): Governs involuntary internal functions like breathing, heart rate, and digestion. It is further divided into:
  • Sympathetic Division: Prepares the body for emergencies ("fight or flight") by increasing heart rate, breathing, and blood flow to muscles.
  • Parasympathetic Division: Calms the body down after an emergency and conserves energy ("rest and digest").

The Endocrine System

The endocrine system consists of a set of ductless glands that secrete chemical substances called hormones directly into the bloodstream. These hormones play a crucial role in regulating development, behaviour, and mood. This system works in conjunction with the nervous system and is often called the neuroendocrine system.

Major Endocrine Glands and their Functions:

Heredity: Genes and Behaviour

The study of how we inherit physical and psychological characteristics from our ancestors is called genetics. This inheritance provides the biological blueprint for our development.

Chromosomes

Chromosomes are thread-like structures found in the nucleus of every cell, which carry our hereditary information. Humans have 46 chromosomes, arranged in 23 pairs. We inherit 23 chromosomes from our mother and 23 from our father. The 23rd pair determines our biological sex:

• XX: Female
• XY: Male

Genes

Chromosomes are made of Deoxyribonucleic Acid (DNA). A gene is a specific segment of DNA that contains the instructions for building proteins, which in turn regulate our physiological processes and the expression of our traits.

• Genotype: Refers to the actual genetic makeup of an individual, which is inherited from the parents.
- Phenotype: Refers to the observable traits of an individual, such as their body build, height, or intelligence. The phenotype is a result of the interaction between the genotype and the environment.

Modern sociobiology suggests a theory of dual inheritance: biological inheritance occurs through genes, while cultural inheritance occurs through memes (ideas, beliefs, patterns of behaviour). Both forces interact to shape human behaviour.

Cultural Basis : Socio-Cultural Shaping of Behaviour

Biology alone cannot explain the vast complexity of human behaviour. While basic needs like hunger have a biological basis common to all animals, the way humans gratify these needs is heavily influenced by culture. For example, food choices (vegetarian vs. non-vegetarian), eating habits, and social norms around food vary dramatically across societies.

This demonstrates that our behaviour is a product of an interplay between biological predispositions and powerful socio-cultural forces.

Concept of Culture

In simple terms, culture refers to the "man-made part of the environment." It includes all the products of human behaviour, both material and abstract, that are passed down through generations. This includes:

• Material Products: Tools, sculptures, buildings, clothing.
- Ideational Products: Ideas, categories, norms, values, laws. - Social Institutions: Family, school, marriage.

Culture shapes our behaviour by providing us with a shared framework of meaning, values, and practices. However, this relationship is interactive: just as culture shapes us, we also shape our culture.

Cultural Transmission

As human beings, we have a highly developed capacity to learn from our own experiences and those of others. This learning happens through two key processes: enculturation and socialisation.

Enculturation

Enculturation is the process of learning the values, norms, and behaviours of a culture simply by being a part of it, often without direct or deliberate teaching. It is a form of observational learning where we absorb the concepts and practices that are integral to our socio-cultural context. For example, we learn what our culture considers to be "food" or what constitutes polite behaviour largely through observation and immersion in our community. Because this process is so pervasive, we are often unaware of how profoundly our culture has shaped us.

Socialisation

Socialisation is the process through which individuals acquire the knowledge, skills, and dispositions necessary to participate as effective members of their society. It is a lifelong process that involves deliberate teaching and learning, often through reward and punishment, to produce "acceptable" behaviour.

Socialisation Agents

People who have the power to influence and socialize us are called socialisation agents. The primary agents include:

1. Parents and Family: They have the most direct and significant impact on a child's development, teaching them fundamental skills, values, and norms. Different parenting styles (e.g., authoritative, authoritarian) can lead to different developmental outcomes.
2. School: As children spend a long time in school, it has become a major agent of socialisation. Schools teach not only cognitive skills but also social skills, norms, rules, and values like self-control and responsibility.
3. Peer Groups: Friendships become extremely important during middle childhood and adolescence. Interactions with peers help children learn qualities like sharing, trust, and mutual understanding, and play a crucial role in the development of self-identity.
4. Media: Television, cinema, and the internet have become powerful socialisation agents, influencing our thoughts, attitudes, and behaviours, and providing models that adolescents and young adults often emulate.

Acculturation

Acculturation refers to the cultural and psychological changes that result from continuous, first-hand contact with other cultures. This can be voluntary (e.g., moving abroad for a job) or involuntary (e.g., through colonization or as a refugee). Acculturation involves re-learning norms, values, and behaviours, a process that can sometimes be smooth and at other times lead to conflict and stress.

Psychologist John Berry proposed that individuals use different strategies to deal with the challenges of acculturation, based on their answers to two key questions:

1. Is it desirable to maintain my original culture and identity?
2. Is it desirable to have daily interaction with members of the other culture?

Based on the responses, four acculturative strategies have been identified: