Evil, it can seem, is all around us. Hitler. The Rwandan genocide. Ted Bundy. Every time you read the news or watch television, bad behaviour that causes harm is on display.

Is being evil advantageous in some scenarios?

These days, the word ‘evil’ has religious connotations. It’s tied up with morality and transgressions against the will of a divine being. But in its original Old English it meant anything that was simply bad, vicious or cruel.

Assuming we stick to this broader non-religious definition – that evil involves acting in a malevolent way – it’s reasonable to ask why it came into existence. We know that humans evolved from apes and, ultimately, from much simpler animals. That means we get many of our behaviours from our animal ancestors. Does this include evil behaviours – and if it does, is this because being evil is advantageous in some scenarios?

Or to put it another way, can we trace the evolution of evil?

There are many different definitions of the ‘nature of evil’ but we will define it as acts that cause intentional suffering, destruction or damage to B for the benefit of A. To explore further, we can break down those intentional actions into four basic categories: the Dark Tetrad.

Machiavellianism involves using intelligent strategy and cunning to gain power and get one up on a rival

A group of psychologists including Del Paulhus at the University of British Columbia and his student, Kevin Williams, first came up with these categories about 15 years ago. Initially they defined a Dark Triad, which included Machiavellianism (manipulative, self-interested, deceptive), Psychopathy (antisocial, remorseless, callous) and Narcissism (grandiose, proud, lacking empathy). Paulhus later extended the Triad to a Tetrad, to include Everyday Sadism (the enjoyment of cruelty). Why do these behaviours exist in humans? And can they be seen in other animals?

Machiavellianism

Machiavellianism involves using intelligent strategy and cunning to gain power and get one up on a rival. It is a normal part of political life, of course – even if the individuals playing politics aren’t human.

Every individual monkey seems to have the capacity for Machiavellian behaviour

Dario Maestripieri of the University of Chicago has found intriguing, Machiavellian-like behaviours in rhesus monkey societies during his studies over 20 years. Alpha males engaged in threatening behaviour and violent tactics to protect sleeping spaces, females and food.

The dominant monkeys used unpredictable bursts of aggression to rule over subordinates. Alliances were formed and female monkeys looked out for their own daughters by mating with the alpha male – but they also mated with other males behind his back to ensure they would be protected if the alpha male died or was deposed.

In fact, every individual monkey seems to have the capacity for Machiavellian behaviour, says Maestripieri. "It's part of who they are. It's not that there are Machiavellian individuals that do it all the time and others who never do it. Just like humans, it's part of our nature, which doesn't mean we have to do it all the time."

Rhesus macaques act in this way because they desire power, and Machiavellian behaviours are an effective way to establish and maintain dominance, or alliances with dominant individuals. It's not a risk-free strategy, though. If they’re caught cheating there is punishment, says Maestripieri. If a group member was spotted attacking baby monkeys, for instance, they faced retribution.

Where tasks are done cooperatively, Machiavellianism could work in virtually every task you're trying to do

Even so, the many pros of adopting Machiavellian strategies may outweigh these cons, particularly in highly social animals like monkeys or humans.

"Where tasks are done cooperatively, it could work in virtually every task you're trying to do," says Samuel Gosling, professor of psychology at the University of Texas, in Austin US, and a leading researcher into personality types in non-human animals. "Whether it’s foraging, feeding, caring for the young or defending the group."

In fact, you could argue that simpler animals are capable of a rudimentary form of Machiavellianism too. The viceroy butterfly protects itself by mimicking another species that is toxic or disgusting to birds. The anglerfish is so named because of a long filament protruding from its head, with a growth on the end which resembles a fish or a worm. It deceives smaller fish into an unwise attack – they are then quickly gobbled up.

In other words, there is good reason to believe that the intentional deception underlying Machiavellianism has very deep evolutionary roots. It is just such a useful survival strategy.

Psychopathy

It might come as a surprise, but some animals seem to be genuinely unpleasant individuals.

The primatologist Frans de Waal had a chimp in his Arnhem Zoo colony called Puist who he said was "two faced and mean" and "deceitful or mendacious". She was the universally disliked by researchers and compared to a witch.

Jane Goodall, meanwhile, studied a mother and daughter pair of chimpanzees – Passion and Pom – who systematically cannibalised eight infants over four years. Goodall called Passion a "cold mother".

But are these apes psychopaths?

According to the psychologists Peter Buirski and Robert Plutchik, they might be. In 1991 the pair used the Emotions Profile Index, an observational measure, to study Passion. The index includes "deceptiveness, callousness, aggressiveness, absence of emotional ties, and fearlessness" – and it suggested Passion showed socially deviant behaviour.

Some chimpanzees may display psychopathologies

A 2006 study on psychopathology of great apes also considered Passion and Pom. The chimpanzee pair "cannibalised with such persistence that a human psychiatrist is tempted to render this as antisocial personality 'disorder'", wrote the researchers.

They cautioned against pinning too much significance on the word 'disorder' though, writing that, "Whether infanticide is a behavioural abnormality or an adaptive reproductive strategy has been a matter of controversy."

A study in 1999 took 34 chimpanzees in captivity at a research centre in Georgia as the subjects of its 'Chimpanzee Psychopath Measure'. The chimpanzee living quarters were filled with toys, ladders, tyres and plastic barrels for the animals to play with.

It is not just chimps that have been suggested to show psychopathic tendencies

The chimps were examined for traits such as being boredom-prone, failing to learn from punishment, being likely to throw temper tantrums, and likely to tease others. In combination, such traits might suggest a psychopathology.

The researchers were asked to pick the trait that fit best from the Big Five dimensions (Agreeableness, Extraversion, Neuroticism, Conscientiousness and Openness to Experience). The Big Five is a model still used by psychologists to describe human personality.

The team found that there was "evidence for the psychopathy construct in chimpanzees", and concluded that certain features of human psychopathy, such as risk-taking and absence of generosity, were found in great apes. As in humans, male chimps received higher scores than females.

It is not just chimps that have been suggested to show psychopathic tendencies: so have dolphins.

Ben Wilson of the University of the Highlands and Islands in Inverness, UK, was part of a team who observed evidence of violent interactions between bottlenose dolphins and harbour porpoises. Porpoises washed up on the coast of Scotland, then, later, Wales, Southern England and Monterey Bay in California, showed signs of injuries inflicted by the dolphins.

The idea was put around that there were a couple of freaky dolphins, poisoned or psychotic

"The idea was put around that there were a couple of freaky dolphins, poisoned or psychotic," says Wilson.

But it is difficult to back up that idea without more information on the attacks – especially as there are alternative ways to account for the behaviour.

For instance, it is possible that the dolphins were in competition with porpoises for prey, so they simply wanted to get rid of their rivals. However, Wilson points out that dolphins also have a similar diet to seals – and yet they don’t attack the seals.

Alternatively, the porpoise attacks could have something do with infanticide, which has been observed in bottlenose dolphins.

We know that there are good biological reasons for various mammals to kill young. It will happen in lion societies, when a male lion takes over a pride. Maybe there's an equivalent in bottlenose dolphins, suggests Wilson. Getting rid of offspring can be a smart idea because it allows the female to be available to reproduce if she is not looking after a cub.

"If you go to attack a dolphin with a mother defending it, it's a dangerous thing to do – so you might need some practice and a porpoise is a good thing to pick on," says Wilson.

Ultimately, we don't know why bottlenose dolphins sometimes attack porpoises. "There isn't evidence for one theory being right or one single view. All reasons had pros and cons and information that was missing," says Wilson.

Sadism

In the Dark Tetrad, everyday sadism is defined as taking enjoyment in cruelty.

Sadism may allow a person to maintain power and dominance, suggests Paulhus. "It seems like vicious politicians [who] maintain power become more and more sadistic over time and maybe they have to, to stay in power."

He gives the example of Vlad the Impaler who was able to deter enemies from entering his kingdom by hanging bodies on the border, showing invaders what might happen to them if they continued.

Is sadism a behaviour we can recognise in non-human animals?

Wilson says he has seen dolphins swimming under the water popping off seagulls that are sitting on the surface. This behaviour could be interpreted as a deliberately annoying one, but "sadism" carries very moralistic overtones that Wilson rejects – particularly since we do not know for sure that the dolphins are aware of the annoyance they are causing to the birds.

"It's like us popping bubble wrap," he says. The dolphins might behave this way simply for the personal pleasure it brings without recognising that the behaviour is also cruel to the birds.

Perhaps adult animals that act sadistically are actually fixated at the play stage of childhood

"It could just be good practice, effectively play is practice or it could be good fun. Dolphins will barrel boats for ages. It's a very obvious behaviour and still pretty hard to explain apart from that it looks like good fun," he says.

We might associate some of the purest forms of fun with childhood play – and, says Paulhus, perhaps this is one ultimate origin of sadism.

"If you look at animals that play with their victims, they don’t kill them, they torture them," he says. "Maybe that's the connection, to learn to be an adult animal you have to play first and somewhere between play and becoming an adult who has to kill, there's a line. That play aspect carries over to some adults, they're actually fixated at the play stage, they never got over it."

So perhaps sadists are really displaying a form of arrested development. If this is the case, it might seem odd that the behaviour can exist over the long term in adult societies.

Paulhus has a theory. "You could consider the dark personalities to be parasites in different ways," he says. "In animal communities parasites do serve a very positive function. One argument that could be made is they clean up the less adaptive individuals, those in the herd who didn’t quite have the qualities to contribute."

It is a morally troubling argument, but perhaps Dark Tetrad behaviours are, paradoxically, beneficial to human and animal societies by encouraging other individuals to be on their guard and think carefully about their trust. "They are keeping the species fit in a way," says Paulhus.

Narcissism

The vanity associated with narcissism would seem to be a purely human characteristic. But is it? Can we draw any comparisons between the charm and charisma of a narcissist and the lengths some animals will go to in order to draw attention to themselves?

A male peacock with his beautiful tail, the scented pheromones of a fox, the dance of the bowerbird. We can’t be sure that non-verbal animals are purposely grandiose, but do these ostentatious displays give us some indication of how narcissism evolved?

Explaining the extreme selfishness often associated with narcissism might be easier if you take a gene’s view of evolution. Famously, of course, Richard Dawkins wrote about the selfishness of genes – arguably their one and only "goal" is to perpetuate down the generations, and it matters little to genes if their success comes at a cost to other genetic sequences – or the organisms they are housed within.

Explaining the extreme selfishness often associated with narcissism might be easier if you take a gene’s view of evolution

While humans have partly over-ruled their original selfish urges and broken out of the governance of selfishness through cultural influence, all livings things are "gene survival machines" – and to a degree this can help explain not only the evolution and survival of narcissism, but also of the other components of the Dark Tetrad.

"There are a variety of avenues to reproduction," says Paulhus. "Some of them we might [now] consider to be unacceptable but they worked apparently in the past."

For instance, the psychopath and the Machiavellian may have – or have had in human history – more sex than most people because of some tendency towards promiscuity associated with their behaviour. "You can persuade and manipulate partners a lot better if you think strategically without empathic concern for hurting another's feelings," says Paulhus.

"The narcissist feels special and exudes confidence that people react to, and that provides opportunities for reproduction," he says.

Why sadists might have a reproductive advantage is harder to explain, he concedes. "Presumably in the past [sadism] allowed you to exude more power – and power leads to reproduction."

"Nature, red in tooth and claw," wrote Tennyson, about the violence of the natural world. There are certainly many examples to support his description. In Brazil, the margay cat mimics the sound of a wounded baby pied tamarin monkey, to deceive and entice its prey.

The female praying mantis will often chomp the head off and eat her mate after sex, sometimes even in the middle of the act. Hyena cubs will kill siblings from the moment they are born. Even plants use deception: the bee orchid tricks the male bee into pollinating it by mimicking the female insect.

Arguably the real mystery lies not in the origin of "evil" behaviours but in the fact that humans now generally view these behaviours as distasteful – even though deception, selfishness and other "evil" traits appear to be widespread in nature, and generally beneficial for the survival of genes, animals and species.

John Armstrong, a British writer, and philosopher at The School Of Life, sees a gulf between human aspiration for justice and ethics and the laws of nature. Often we feel that something that is "evil" is against the natural order of things, or, as Armstrong put it, "at odds with everything one might hope for".

But perhaps the opposite is actually true: it is "bad" behaviour that is natural and successful. "What's surprising is how amazingly well (though still very imperfectly) human beings have tried to reverse this natural arrangement," he says.