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"Two canine animals, in a time of dearth, may be truly said to struggle with each other which shall get food and live." Not quite 'dog eat dog', but thus did Charles Darwin describe the tireless struggle for existence that is a trademark of the natural world.

In 1976, evolutionary biologist Richard Dawkins went on to reinforce this view by describing organisms as merely vehicles for the true drivers of evolution: genes. "A predominant quality to be expected in a successful gene is ruthless selfishness," says Dawkins. Further, "this gene selfishness will usually give rise to selfishness in individual behaviour".

Dawkins suggests the principle of the 'selfish gene' paints the world in a harsh and pitiless light, in sharp relief to the world we might want to inhabit. "As we might wish to believe otherwise, universal love and the welfare of the species as a whole are concepts that simply do not make evolutionary sense."

So, are we born into this cruel world merely to spite our fellow man and surge only towards our own selfish ends? Is it truly the case – as given voice in the film Wall Street by corporate raider, Gordon Gekko – that "greed is good"? If so, whence springs our "wish to believe otherwise", of which Dawkins makes mention? And how can this wish be explained in the harsh light of evolution?

THERE'S NO QUESTION we have selfish desires and impulses. However, it's clear that this is not all there is to the complex human psyche. Consider the following scenario and reflect on how it makes you feel:

"You're sitting in a lifeboat on dark and turbulent seas. You're cold and wet. But that's the least of your worries. As the captain, the lifeboat and its occupants are your sole responsibility. Designed to hold no more than a dozen, the lifeboat is overloaded with 20 survivors. On the horizon looms a menacing thunderstorm. You face a choice. If you allow currents to drag the overloaded boat into the storm, it will surely sink and all hands will perish. However, if you can reduce the number of occupants to 12, then you stand a chance of survival and rescue.

What do you do? And how do you feel about it?

Do you order eight people overboard? Whom do you choose? The sick, elderly woman? The convict? The children who are unable to row? The overweight man burdening the boat?

What if someone volunteers? What if one of the women on board is pregnant? What if the elderly woman is your mother, or the children are yours? What if the convict is the only one strong enough to row?

Dilemmas like these have caused consternation amongst ethics students in universities worldwide. Yet the anguish we feel reveals some insight into the way we see the world.

The problem is, were this truly a dog-eat-dog world, we'd have no compunction in committing our fellow survivors to the waves to ensure our own survival (or the survival of our genes – the true masters of the ship). Yet we do have scruples about such a ruthless act, even in the face of our impending demise.

So why is it that we feel so strongly about morality?

Several thousand years of philosophy, from Socrates to Singer, and morality remains an enduring enigma. In fact, where philosophers once attempted to advise us on how to live a virtuous life, in the 20th century this practice waned. A pervasive scepticism as to whether it was possible to derive such a thing as an objective morality, or moral 'truths', led many thinkers to descend into moral relativism, or to simply debate semantics rather than offer guidance.

Yet from this philosophical quagmire has arisen an unlikely champion of moral insight: science. Research in the late 20th and early 21st century in a variety of fields, including cognitive psychology, evolutionary biology and game theory has come together under the banner of evolutionary psychology to offer a fresh perspective on morality – one that may shed new light on its origins and applications.

As stated by pioneering evolutionary psychologists Leda Cosmides and John Tooby, from the University of California in Santa Barbara, "the human mind is the most complex natural phenomenon humans have yet encountered, and Darwin's gift to those who wish to understand it is a knowledge of the process that created it and gave it its distinctive organisation: evolution."

IT'S VERY LIKELY you're far better at moral reasoning than you might think. Try the following task:

"Your job is to test whether the following statement is true: when Fred travels to Sydney, he always takes the train. In front of you are four tickets, each representing four different trips. One side has the destination, the other side shows the method of transport, whether it be bus or train. If you were going to check that the above rule was true, which two tickets would you need to turn over to confirm it?"

If you said you'd turn over the first and third tickets to check the rule, then you're in the majority. However, that's not the right answer.

Now consider the following task along similar lines:

"You're serving drinks behind a bar, and your job is to ensure that nobody under 18 is drinking alcohol. There are four people sitting at a table nearby drinking. You can clearly see what two of the individuals are drinking – a beer and a soft drink respectively – but you can't see how old they are. You can also see the age of the two other individuals at the table – 25 and 15 respectively – but you can't see what they're drinking. This scenario is represented by the cards below, with the drinker's age on one side, and their beverage on the other. If you were going to make sure that no one under 18 is drinking an alcoholic beverage, which two cards would you need to turn over?"

If in this case you said cards one and four – that you'd need to check the beer drinker wasn't under 18, and that the 15-year-old did not have an alcoholic drink – then you'd be absolutely right. (It doesn't matter how old the second person is because they're drinking a soft drink. It also doesn't matter what the 25-year-old is drinking because they can drink whatever they like.)

The interesting thing about these two tasks is they are of exactly the same logical form: if P then Q. As such, they both have the same reasoning and the same solution. However, it's not intuitive that in the first test you need to check ticket four – the one going via bus (or not-Q) – to see whether it had Sydney (or P) on the other side. If it did say Sydney, then it would disprove the rule in the same way that if the 15-year-old had a beer it would break the second rule.

This test, called the Wason selection task, was pioneered in 1966 by Peter Wason and was explored by Cosmides and Tooby in the 1992 book they edited along with Jerome Barkow, The Adapted Mind. They discovered that while less than a quarter of respondents chose the correct answer for tests such as the first, more than three quarters had no trouble with the second. To Cosmides and Tooby, this finding implied that we had some kind of hardwired capacity in the human mind for understanding social exchanges, even when the abstract logic involved was not necessarily intuitive.

Why would we have such hardwired intuitions about social exchanges? According to Cosmides and Tooby, "in order to successfully engage in social exchange – cooperation between two or more individuals for mutual benefit – humans must be able to solve a number of complex computational problems."

The key here is "cooperation between two or more individuals for mutual benefit", which is often called 'reciprocal altruism' (you scratch my back, I'll scratch yours). We see this kind of behaviour elsewhere in nature too (see "The moral animal", p54), and as Cosmides and Tooby have stressed, we apparently have in-built mechanisms for handling it.

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