Niko Tinbergen, a pioneer in the study of animal behavior, wisely observed that four questions need to be asked for all products of evolution1.

  1. Given that a trait is an adaptation, what is its function that contributes to survival and reproduction?
  2. Given that evolution is a historical process, what is the phylogeny of the trait?
  3. Given that all traits (including behaviors) have a physical basis, what is the mechanism of the trait?
  4. Given that all traits must come into being during the lifetime of the organism, what is the development of the trait?

Tinbergen’s four questions apply to any variation-and-selection process, including but not restricted to genetic evolution2. Accordingly, they can be insightful for the study of moral universals and particulars as products of human genetic and cultural evolution.

Function: The most general statement that can be made about human morality is a functional one: In virtually all cultures, most people have a sense of right and wrong that corresponds to the welfare of their groups. Also, most people create, abide by, and enforce norms on the basis of what they regard as right and wrong. Notice that this generality is statistical in nature. It admits the possibility that some individuals might not qualify as moral. For example, psychopaths are said to lack a sense of right and wrong, treating everything as instrumental to their desires3. In most experimental games that measure cooperative behavior, a sizable fraction of individuals don’t cooperate and/or don’t punish norm transgressions4. Nevertheless, enough individuals behave morally in virtually all cultures so that the cultures function as moral systems.

Tinbergen’s four questions apply to any variation-and-selection process, including but not restricted to genetic evolution. Accordingly, they can be insightful for the study of moral universals and particulars as products of human genetic and cultural evolution.

Phylogeny: The reason that we are psychologically endowed to behave morally, to the extent that we do, is because of a historical process of between-group selection. As Darwin conjectured long ago, individuals who behave morally are vulnerable to more self-serving individuals within their own groups, but groups of individuals who behave morally robustly out-compete groups whose members can’t pull together. The fact that between-group selection (favoring the traits associated with morality) is often opposed by within-group selection (favoring the traits associated with immorality) explains why all of us behave immorally at least some of the time and some of us more than others. Insofar as different environments call for different behaviors to benefit a given group, the specific behaviors that count as moral can be highly variable. Also, not everything that evolves is an adaptation. There are byproducts, products of drift, and mismatches (adaptive in past but not present environments) for cultural in addition to genetic evolution. Thus, Tinbergen’s Phylogeny question can explain a lot of moral particularism.

Mechanism: What takes place in our brains when we behave morally? The answer might be “it depends”. One person might behave out of a sense of duty. Another might take pleasure in helping others. Another might be trying to earn a ticket to heaven. There is inherently a one-to-many relationship between the function of a trait and the proximate mechanisms that evolve to cause it. This is important because philosophers often reason on the basis of their own moral intuition as if it must be culturally universal. There is no warrant for this assumption from an evolutionary perspective. We must realize that the proverb “there are many ways to skin a cat” applies to the mechanisms underlying moral behaviors along with many other kinds of behaviors.

Development: Our core psychological ability to function as moral agents might qualify as universal or nearly so, with developmental stages that are correspondingly universal. However, the particular moral systems and their underlying mechanisms that evolve in any particular culture will also have particularistic developmental pathways. This will require a rethinking of some stage theories of human moral development. For example, in Kohlberg’s theory of moral development5, the highest stage is driven by universal ethical principles. When this “stage” is reconceptualized as a moral system that competes against other moral systems, it requires very special conditions to evolve, which accounts for the fact that most individuals and cultures don’t achieve it. Creating such a moral system is an important normative goal that I share, but there is no warrant for calling it a stage in a developmental sense.

While the topic deserves much more than a short commentary, Tinbergen’s four questions might prove as useful for organizing the study of morality as for all other products of evolution.


  1. Tinbergen, N. (1963). On aims and methods of ethology. Zeitschrift Für Tierpsychologie, 20, 410–433.
  2. A lecture that I frequently give on Tinbergen’s four questions is available online at
  3. O’Conner, L. E., Berry, J. W., Lewis, T. B., & Stiver, D. J. (2011). Empathy-based pathogenic guilt, pathological altruism, and psychopathology. In B. Oakley, A. Knafo, G. Madhavan, & D. S. Wilson (Eds.), Pathological Altruism (pp. 10–30). Oxford: Oxford University Press.
  4. Fehr, E., Fischbacher, U., & Gachter, S. (2002). Strong reciprocity,human cooperation, and the enforcement of human social norms. Human Nature, 415, 137–140.
  5. Kohlberg, L. (1984). Essays on Moral Development: Vol. 2. The Psychology of Moral Development. San Francisco: Harper and Row.

This article is from TVOL's project titled “This View of Morality: Can an Evolutionary Perspective Reveal a Universal Morality?” You can download a PDF of the project [here], comment on this article below, or comment on the project as a whole in the Summary and Overview.