In the world of behaviour analysis, we often focus on what we can observe and measure in the here and now. But understanding behaviour in its fullest sense requires looking at how it came to be — not just for the individual, but across evolution, learning history, and cultural context. These three levels of behavioural selection—phylogeny, ontogeny, and culture—are like layers of a rich tapestry that shapes human behaviour.
1. Phylogeny: Behaviour Shaped by Evolution
Phylogeny refers to the evolutionary history of a species. Across millennia, behaviours that improved survival and reproduction have been selected. Consider reflexes we are born with: the startle response or grasp reflex aren’t taught; they are inherited and passed down because they helped our ancestors survive.
For behaviour analysts, phylogeny reminds us that some behaviours are deeply rooted in biology. For example, understanding the evolutionary function of avoidance behaviour (to protect oneself from harm) can help practitioners approach their work with compassion and respect when encountering such responses in individuals.
2. Ontogeny: Behaviour Shaped by Experience
Ontogeny is the story of an individual’s learning history. It encompasses the effects of reinforcement, punishment, and other environmental contingencies on behaviour. This is where applied behaviour analysis (ABA) primarily operates: analysing and influencing behaviour based on the person’s unique experiences.
For instance, if someone frequently engages in a specific habitual action, it’s crucial to explore their ontogeny: What environmental variables maintain the behaviour? Does it serve a sensory-regulatory function, provide social connection, or meet a practical need? By understanding this level, practitioners can design interventions that respect individual needs while promoting autonomy and meaningful change.
3. Culture: Behaviour Shaped by Social Systems
Culture represents the shared practices, norms, and values of groups of people. It influences behaviour at a macro level, shaping how individuals interact with one another and their environment. Cultural contingencies can dictate which behaviours are reinforced or punished, often in ways we don’t consciously recognise.
For behaviour analysts, acknowledging cultural factors is essential. When developing interventions, it’s vital to consider the values and expectations of the individual’s cultural context. For example, the expectations for eye contact vary across cultures; while it might be highly valued in some societies, others may find prolonged eye contact uncomfortable or inappropriate.
Integrating the Three Levels
Although these levels are distinct, they are deeply interconnected. A person’s behaviours might be influenced by their evolutionary history (phylogeny), their learning experiences (ontogeny), and the cultural norms of their community (culture). Effective behaviour support must consider all three levels to create holistic, individualised plans.
Why Does This Matter?
Understanding the three levels of selection helps us move beyond a one-size-fits-all approach. It encourages us to:
Promote human rights:
Recognise and respect individual differences, including those rooted in biology and culture.
Support autonomy and choice:
Improve Quality of Life
Reflecting on these levels, practitioners can deepen their understanding of behaviour and provide more compassionate, effective support. It’s not just about changing behaviour—it’s about understanding it, respecting it, and working collaboratively to create lasting, positive change. By staying curious and reflective and engaging in philosophic doubt, we continue to grow as practitioners and better serve those we support.
Which of the following areas do you feel most influences your practice as a behaviour analyst?
Evolutionary functions of behaviour (phylogeny).
Individual learning history (ontogeny).
Cultural and social systems (culture).
Integrating all three levels.