How would you define behaviour?
It may be harder than you think
Hello again all!
I hope you have had a good weekend. Today, I would like to discuss something which seems trivial and intuitive, but is really something more complex than you may intially think, and it is something which even experts in the field disagree upon. That is our definition of what behaviour is.
There are, of course, numerous published definitions, and for many biologists the meaning is simply and clearly intuitive. However, satisfying definitions of this word, in the context of modern biology, are hard to find. Many definitions are so vague as to be impossible to apply, while others are crafted around a particular taxon such that members of other taxa cannot “behave” due to a lack of the specific physiological features which are required by the definition, such as muscles or a nervous system.
In science, precise definitions are important, and yet there are multiple defintions within the field of ethology which are both contradictory and imprecise. For example, one of the founders of the field of ethology, Niko Tinbergen, described behaviour as "‘the total movements made by the intact animal’ (1955), which has obviously failed to keep pace with the progression of the field.
There has in fact been a study conducted on this very topic. Levitis and colleagues (2009) published a paper in Animal Behaviour titled “Behavioural biologists do not agree on what constitutes behaviour”. The basis of this paper reports on the lack of concensus for a unifying definition of behaviour. What they found was rather intriguing, as the title alludes to.
Levitis et al. designed a survey, consisting of various published defintions of behaviour, and various (some fictious, such as “frog orbits sun”) examples of behaviour. This survey was answered by 174 members of the Animal Behavior Society, the International Society for Applied Ethology, and the Society for Plant Neurobiology, at various levels of expertise (denoted as 1,2, and 3 respectively). Their results showed that existing the definitions of behaviour did not generally agree on what is or is not behaviour, and generally did not meet the requirements of our rules for definitions. Furthermore, behavioural biologists “showed a corresponding confusion over the meaning of ‘behaviour’”. This was the case as over 50% of the people surveyed gave contradictory answers, showing that people tend to rely on inference when regarding behaviour, rather than a singular defintion.
So should we do as one biology professor is claimed to have commented “‘I know it when I see it, hear it, smell it, feel it or electrically sense it’? Is this satifactory for defining behaviour? Levitis et al. would disagree, and offer a new definition based on their survey responses:
Behaviour is the internally coordinated responses (actions or inactions) of whole living organisms (individuals or groups) to internal and/or external stimuli, excluding responses more easily understood as developmental changes.
Whether this definition is truly fitting or not to describe the myriad of behaviour of the hundreds of species which inhabit earth, this is discussed in Levitis et al.s paper. Nevertheless, definitions are in a sense arbitrary and free to change as knowledge adavnces, due to the fact they reflect the consensus wisdom of the current time. As such they are important as expressions of current conceptual perspectives, and are useful if they provide guidance for students and practitioners in a discipline. Levitis et al. close their discussion by saying that they do not posit that their definition is in any way conclusive, but rather that they simply hope it will spark discussion on what is meant by the term “behaviour”.
In a similar way, I hope that this blog post sparks some discussion or introspection on the topic, as I believe it is one that is intrinsically important to the field, as is the ongoing and dynamic debate of what defines a “species” in the field of ecology.
Until next week,
B.