The Biology underlying Human morality

By William Carter

The roots of human morality have long been attested to lie in our likeness to the divine, and discussion on the matter reserved for philosophers. This article will make the case that there are innate human morals arise from our evolutionary process and are enshrined in our genome.

Developmental psychology for many years adopted a somewhat Hobbesian position that babies were awful little brutes in desperate need of civilising; boorish brats who must be taught to tell right from wrong.

Ongoing research, however, has refuted this assumption and given us insight into infants’ moral sensibilities. More and more evidence is emerging to support the notion of an innate, rudimentary moral sense present and active in children of any age. Through careful experimentation, moral thought, moral judgment and moral feeling have all been demonstrated in infants, even within their first year. A prime example of such research involved a puppet show where three puppets play a game with a ball (Wynn, Bloom, 2014) . One puppet standing in the middle would pass the ball to the other two. When the first (nice) puppet received it, he would pass it back, whereas the second (mean) puppet would take the ball and run away. Having watched this unfold, the young participants were presented with the two puppets, both placed next to a few treats each. The infants were then asked to take a treat away from one of the puppets. In a significant majority of cases, the children took treats away from the ‘mean’ puppet, indicating their disapproval, with some particularly vindicative babies smacking it for extra punishment. Many similar experiments investigating infants’ moral sense have been conducted and replicated, providing significant evidence for a foundational and innate moral intuition. It follows from this assertion to ask “where does this instinct come from?” 

The evolution of learned behaviours into instinct is explained by the Baldwin Effect, which says that a genetic predisposition to learning certain beneficial skills or behaviours faster and more effectively will be selected for in the population (Baldwin, 1896). We usually think of evolution acting on physiological traits, but the Baldwin Effect asks us to consider genes’ indirect role in predisposing behaviour, and how selective pressures can promote certain behaviours (Bateson, 2004).

For example, consider a population of initially earth-bound mammals living in an environment with little available food, save for the many nutritious fruits growing high up in the trees, tantalisingly out of reach. Being able to climb up into the canopy and access those untapped resources would be greatly advantageous, however, it is dangerous and the skill takes a long time to learn. An individual born with a gene that predisposes them to be a fast learner or a better climber will therefore have a net competitive advantage – he can learn to climb and reach the fruit on the trees before other individuals in the population, meaning he is less likely to die doing so. Therefore, this gene will be selected for over time, given it has no major deleterious effects elsewhere in the organism.

It is through the Baldwin Effect that our innate moral intuitions are believed to have developed. This of course asks the rhetorical question, how could altruistic, moral behaviour -helping and caring for others- be advantageous to the survival and reproduction of the individual? We will consider two of the main explanations for altruistic, or ‘moral’ behaviour, glossing over a few of the less significant contributing factors. 

First, there is the case of genetic kinship (Smith, 1964). Consider natural selection working at the level of genes, a perspective championed by Dawkins, with the aforementioned ‘genetic predisposition’ attributed for simplicity directly to a given ‘gene’. Genes are selfish and pilot our bodies with the sole purpose of being transmitted to the next generation. A gene that confers any advantage to this process of transmission will be selected for. As a specific gene can exist in many individuals at any one time, a gene in one individual that can benefit its exact copy in another individual will still provide an overall advantage to its transmission. 

For example, a gene that makes a certain animal more likely to share its excess food with its close relatives, will more likely be transmitted, because of the statistical likelihood that those relatives will share copies of that same gene. In this way a gene predisposing an individual to exhibit altruistic behaviour towards their kin will be selected over many generations and become common in the population. 

Second, there is the case of reciprocal altruism, sometimes called symbiosis, which does not depend on shared genes (Trivers, 1971). Take the classic example of the honeyguide and the honey badger (Zimmerman, Turner, Pearson, 1999). The honeyguide can find bees’ nests, but can’t break into them. Conversely the honey badger can’t find the nests, but can break into them. This asymmetry between them brokers a deal, the honeyguide guides honey badgers to the bees’ nest using an enticing flight pattern, and the badger breaks open the nest. Working together both can reap the spoils, whereas apart neither could, aptly demonstrating reciprocal altruism. 

Consider this in terms of the Baldwin Effect, how millennia ago a single pair of ancestral honeyguide bird and badger learned to cooperate. Over countless generations, both the honeyguide and the honey badger become genetically predisposed to behave in this reciprocally altruistic and beneficial way. The case of the honeyguide and the honey badger is one of many; every environment is rich in such mutualistic relationships. Natural selection will favour genes that predispose individuals to exhibit these altruistic behaviours, as they are beneficial to all parties. 

In his book, “The Science of Good and Evil” (Shermer, 2004) the following characteristics are noted of what could be considered moral, human behaviour, are shared by other social animals, particularly the great apes:

“attachment and bonding, cooperation and mutual aid, sympathy and empathy, direct and indirect reciprocity, altruism and reciprocal altruism, conflict resolution and peace-making, deception and deception detection, community concern and caring about what others think about you, and awareness of and response to the social rules of the group.”

Such advantageous behaviours will have been selected for over our evolutionary history as social creatures, equipping us at the genetic level with a basic moral instinct (Sznajder et al, 2011).

Throughout their history humans have lived under conditions that would have strongly favoured these altruistic behaviours. Living in small communities, consisting largely of close relatives in close daily contact – these were the perfect circumstances for the evolution of both kin and reciprocal altruism. These primitive instinctual inclinations exist within us today, codified first and foremost in our genetics, and developed over millennia of human culture and civilisation into morals.


Baldwin, J., (1896). A New Factor in Evolution. The American Naturalist, 30(354), pp.441-451.

Bateson, P., (2004). The Active Role of Behaviour in Evolution. Biology & Philosophy, 19(2), pp.283-298.

Smith, J., (1964). Group Selection and Kin Selection. Nature, 201(4924), pp.1145-1147.

Trivers, R., (1971). The Evolution of Reciprocal Altruism. The Quarterly Review of Biology, 46(1), pp.35-57.

Shermer, M., (2004). The Science of Good and Evil. New York: Times Books. pp. 16

Sznajder, B., Sabelis, M. and Egas, M., (2011). How Adaptive Learning Affects Evolution: Reviewing Theory on the Baldwin Effect. Evolutionary Biology, 39(3), pp.301-310.

Wynn, K., & Bloom, P., (2014). The moral baby. In M. Killen & J. G. Smetana (Eds.), Handbook of moral development, pp. 435–453.

Zimmerman, D., Turner, D., & Pearson, D., (1999). Birds of Kenya and Northern Tanzania. Princeton University Press. p. 406.

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