Evolution of human morality



Human evolutionary history

The family lines of human beings and of our nearest relatives, chimpanzees and bonobos, split from each other 67 million years ago.  One of the first species in the Homo genus, Homo erectus, arose about 1.8 million years ago in Africa.  

It is thought that around 2 million years ago, the Earth underwent a drying and cooling phase which led to a shrinkage of the forests and an expansion of grassland environments in Africa, and so, an increase in the numbers of ground-dwelling monkeys that competed with the first humans for plant foods, obliging them to take up scavenging meat, and later, actively hunting big game; and to find vegetable foods not available to monkeys, such as deep-down roots and tubers, which could only be obtained and processed by adults.  

Homo heidelbergensis is thought to have descended from Homo erectus around 8 hundred thousand years ago.  There is evidence for Homo heidelbergensis making wooden spears, bringing large prey back to a home base, and using fire in a controlled way from about 4 hundred thousand years ago.  

Our species, Homo sapiens, is thought to have descended from the African population of Homo heidelbergensis about 2 hundred thousand years ago.  

Our sister species, “Neanderthal man”, Homo neanderthalis, descended from the European population of Homo heidelbergensis.  

Nova documentary on Homo erectus here



Closest relatives

The two closest relative species to humans are chimpanzees and bonobos.  Both species are the only other great apes apart from ourselves who live for most of their lives in mixed social groups of numbers of males and females, rather than solitary or in harems or single parent units.  

In chimpanzees, males are dominant and form alliances with each other within an overall dominance hierarchy, and conflicts are generally settled by fighting followed by reconciliation.  Their intelligence is “machiavellian” – a chimpanzee can understand the goals and intentions of another, but tends to use this knowledge for the purpose of competition and manipulation.  Male chimps will sometimes kill infants that we presume are unrelated to them, and female chimps will avoid large gatherings of chimpanzees for years after giving birth.  

In bonobos, females are dominant and form alliances with each other, while males have their own dominance hierarchy and are not known to form alliances.  Food for bonobos is plentiful compared with that of chimpanzees.  In bonobos, conflict is settled with affectionate sexual contact.  Bonobos are known for their empathic intelligence – they will often help others in response to need.  Male infanticide is unknown.   



Inter-breeding between species and lack of warfare

The archaeology of prehistoric humans shows a lot of evidence of interbreeding between species, no evidence of organised warfare, and just the occasional outbreak of violence [ref. Spikins].  The first evidence of warfare is from around 12,000 years ago, at the time when farming and settlements were beginning [ref. Fry].  As a cooperative species whose members (we believe) relied on each other to survive, we would expect early humans not to fight but to collaborate when encountering a stranger on the savannah, even of a different species of person [ref. Hrdy].  



Origins of morality

It seems that the evolutionarily unique moral development of the human species can be traced to two fundamental factors: the existing social, moral and cognitive skills of our great ape ancestors; coupled with those early humans being forced to survive in a difficult ecological environment (the African savannah) where most of the easily obtainable food was already taken by ground-dwelling monkeys.  

The difficulty in obtaining food would have meant that getting enough to eat was necessarily a team effort within small groups of humans.  One person cannot feed themselves on their own on the savannah for long, let alone raise a family.  

The tasks that humans have to do together are much more sophisticated and difficult than those of other animals, requiring sophisticated coordination and communication, which in turn require the evolution of sophisticated cognitive and social skills.  

In collaborating to survive, self interest becomes joint interest.  

Working together requires that people help each other along the way, and find ways to divide up the spoils of their efforts such that everyone is happy and people survive as best they can.  This situation laid the foundations for the particular moral values of the human race including targeted helping, fairness, honesty, monitoring of self and others (shame / pride / reputation), and a sense of right and wrong.

The rise of large groups and the need for coordination, cooperation and trust within groups of strangers on a large scale led to standardised cultural practices and organised religion (whose members demonstrated that they may be trusted), and the competition for resources between these expanded groups led to inter-group opposition and warfare.


See also: definition of goodness, cooperation, fairness, empathy