A mother gray langur (Semnopithecus entellus) holding her infant. Photographer: Nevil Zaveri.
Humans, Homo sapiens, are primates. Our unique genetic heritage can be traced back to 85 million years ago, when the distinctive order of Primates arose from mammals. It took more than 82.5 million years for the first hominids (ancestors belonging to our genus, Homo) to evolve. This first species of the genus, Homo habilis, fashioned rudimentary stone tools and lived in small groups similar in size to modern chimpanzees. This small group size afforded two distinctive advantages: protection from predators and enhanced efficiency in food gathering. In other words, our ancestors cooperated to survive (much like we do today). However, it wasn’t for another two million years and many evolutionary steps later, that the first anatomically-modern humans evolved (between 400,000 and 250,000 years ago). During this long stretch of evolutionary time, and even in the relatively short period since, humans have evolved to become the type of animal they are today – flaws and all.
The consequence of this, is that as our societies and technologies have progressed, various traits and features which once ensured our species’ development and survival are now less relied upon or are altogether inappropriate. These include anatomical vestiges, like the recurrent laryngeal nerve, which instead of running directly from the upper parts of the vagus nerve in the head and neck to the larynx (our voice box), it makes a massive detour down to the heart and back up again. This same anatomical vestige exists in the giraffe, where the nerve travels from the top of the neck all the way down, around the heart, and back up again. This unnecessary and indirect route is all due to the fish, where this nerve first developed and had a very direct route. Humans also possess behavioural vestiges like the ‘goose-bumps’ reaction we get when we are cold (which helped keep our hairy ancestors warm) and when we are frightened (which helped make our hairy ancestors look bigger, meaner, and more threatening to potential attackers).
It’s probably unimportant for us to bother changing the routes of our nerves to be more efficient, or removing now-innocuous in-built behaviours like ‘goose-bumps’, but would it be worthwhile (or is it even possible) to change our innate human intuitions which influence what we call morality? In the case of impartialist normative theories, I think we can consciously reason past them to some extent and that this is worthwhile, but we are sometimes working against the grain of our biological hardwiring.
Though this is not always and completely the case. Sun-tailed monkeys, Cercopithecus solatus, a fellow primate, are known to make warning calls to their group when they spot nearby predators. However, this also generates attention from the predator and generally increases the chance of the individual who makes the warning call of being captured as prey. Through an ethical lens, this seems like a heroic case of self-sacrifice for the good of the many. But how many exactly and what is their relation to this many? Since their mean group size is 17 individuals, and these individuals both know and are closely related to one another, it might not have the same gravitas as the archetypal, heroic self-sacrifice we might imagine of some humans – whether historical or mythical figures like William Wallace and Hercules, or more recent activists like Gandhi and Martin Luther King Jr.
This type of kin altruism exhibited by sun-tailed monkeys (and other species), whereby altruism is limited to a few known, especially related, individuals, is also shown in humans. In a psychological experiment on humans lead by Jens Koed Madsen from University College London, participants held a painful skiing position for as long as they wished to, and the longer they held that position, the greater a reward was for a related family member. Participants held the painful position longest for those they were related most closely to, confirming that human altruism is affected by the relatedness to the benefiting individual.
While we may have evolved to be partial to those closest to us, and impartialist theories like utilitarianism and Kantianism go against this evolutionary bias, it is helpful that we have at least some intuitive altruism (albeit not necessarily ‘true’ altruism – it being, in natural contexts, directed primarily or exclusively towards our kin, i.e., kin altruism). Nevertheless, using sound argumentation to extend this altruism may enable us to direct our intuitive altruism towards a larger number of less-related individuals, like the millions around the world suffering and dying from preventable causes.
However, reason might not always win over vestigial moral intuitions, at least at first. Jonathan Haidt’s psychological experiments on moral knee-jerks to what could be reasoned as a morally acceptable instance of incest, demonstrated that (at least in our initial reaction to some scenarios) our intuitions can persist in spite of being demonstrated as unreasonable. This could indicate that reason simply takes its time or needs to be very convincing to have an effect on our thinking.
Tom Burns 
Interesting. I was wondering if you could provide examples of somewhat ‘vestigial’ moral intuitions and what are the logical impactions of these if examined. Perhaps we have no adequate moral reason for many of our actions but rather our beliefs are based on evolution… Would be interesting if you could provide this. Thank you.
Keep up the work
That’s a great question, and I suspect it changes from person to person, and is partly determined by how much these vestiges have already been driven out of by logic or experience.
Good examples, I think, are common when it comes to sex. Inexplicable aversion to homosexuality, for instance. I’ve written a bit about these ‘moral knee-jerks’ here: http://www.huffingtonpost.co.uk/tom-burns/on-hospital-heating-and-m_b_5142667.html