Dolphins Saving People: Dolphins and Altruism

Are dolphins moral agents? Exploring altruism, and reports of dolphins saving humans

I recently watched a BBC Natural World documentary about a group of dolphins that purportedly saved some humans from a Great White shark attack, and it got me excited about altruism all over again.

A little about bottlenose dolphins – they vary in length between 2 and 4 meters, and weigh anything from 150 to 650 kilograms.1 They are highly intelligent: with large brains, and accomplished cognitive abilities that have been studied since the late 1970’s.2

There are many stories of dolphins saving humans, although evidence for such encounters is usually thin on the ground. The BBC, in their nature documentary ‘Natural World’, documents two such encounters.

The Red Sea Encounter

The first occurred in 1996 in the Red Sea. A single swimmer was attacked by a Mako shark, minutes after he and his friends swam with a small group of dolphins (including juveniles). His friends boarded their vessel, leaving the man alone in the water. Minutes later the attack occurred, and once the victim's friends noticed they sent a small dingy to help him, driven by a single man. The dolphins reappeared, accompanying the dingy at great speed as it raced towards the injured man. The dolphins were within meters of the injured swimmer when he was pulled from the water.

The guy was hit twice by the shark, suffering major injuries to his back and chest. A third hit would have been fatal, yet it never occurred. Did the dolphins ward of this ultimate attack?

The New Zealand Encounter

The second encounter was in New Zealand, North Island, in 2005. To outline the event briefly: a small group of lifeguards in New Zealand were swimming across a stretch of open seawater as an exercise, when a group of bottlenose dolphins appeared. Initially delighted, the swimmers were then gradually herded closer together by the dolphins, which circled tightly around them and under them, bringing their journey to a halt. The whole episode lasted around 45 minutes, with the swimmers becoming increasingly terrified of the apparently aggressive behavior of the dolphins, culminating in some tail slapping of the water. The oldest member of the human swimmers managed to break away, and during this escape he saw a great white shark in the water. Another lifeguard who sped over in a boat to join them saw the shark independently, confirming its presence in the water. After 45 minutes the dolphin circle loosened, then vanished.

So, we have two groups of dolphins putting themselves at considerable risk (Mako’s and Great Whites can eat dolphins) to protect the lives of other individuals. In addition, fantastically, to protect the lives of individuals from a totally different species. A selfless act; is this a golden example of altruism?

Types of Altruism

There are two types of altruism, and both work under the premise that in order for a behavior (or any phenotype) be selected for, to exist, it must ultimately benefit the individual (more precisely, those gene's within that individual that 'encourage' altruistic behavior). The two types are reciprocal altruism, and kin (or nepotistic) altruism.

The theory of kin altruism was first popularized by W.D Hamilton and is elegantly simple: because we share genetic data with our kin, it pays to look after them as well as ourselves, thereby increasing those genes chances of replicating (our genes replicate when we reproduce). We share about half of our genes with a sibling, and in cousins less – we share about an 8th of our genetic data, which is why we generally care less for cousins than for sisters or brothers… the principle continues, and its more thoroughly explained elsewhere.3

Of course, that's not the whole story. Reciprocal altruism compounds this, on the basis that 'if you scratch my back, I'll scratch yours'. This is another simple theory, and its simplicity provides its integrity. It is well documented, is mathematically possible 4, and one can draw many exciting examples.

What motivates a dolphin

So back to the dolphins. What was their motivation? Both groups would have been fully aware of the shark’s presence from a good distance. Obviously it wasn't an example of kin altruism. Reciprocal altruism? The traditional problem with reciprocal altruism is that it only works in relatively small groups, other why's it lays open to exploitation and would be selected out. Specifically, organisms need the ability to identify each individual within the group so a) they can repay the altruistic individual with a similar selfless act, and b) so a 'cheater' doesn't emerge, that takes the offerings of others but gives nothing in return. If nobody could remember who was who, these cheaters would remain faceless and un-punishable – the altruists wouldn't be able to learn by their mistakes and would continue to be duped by the same individual, to their own detriment. The cheater would thus become fitter, propagate more, and drive the altruists to extinction, out of the gene pool. This doesn't happen in small groups because everyone would get to know the cheater, and stop giving him a free ride.

Incidentally, if this is your first brushing with the biological explanations of 'selflessness', they may seem fairly cold and, in fact, selfish. That is the biological truth, and answers to this become more philosophical; required reading if any of this seems deflating!5

It seems we have ruled out both types of altruism, yet we are confident the act took place. Could it have been some incredible form of distant kin altruism? This has been called the ‘green beard effect’, and the answer is slightly more technical, but still a resounding no6. But yet it happened, and similar scenarios have arisen before, although it pays to be skeptical (there’s something irresistible about dolphins saving humans; records of events can easily become romanticized).

Examples of seemingly implausible altruism exist within humans as well; some people in the western world choose to financially support families and children in a developing nation. Acts such as these cannot be explained with the theories we have, and are still curiosities in evolutionary science. One possible explanation is the relatively short time it has taken for our species population to explode to the numbers it has. Not so long ago, it may have paid to help someone outside your own social group, because the likelihood of meeting that individual again, and thus repayment, was great enough to outbalance the expended energy used or risk taken to help them. Perhaps our interest in helping others is due to that influence, and hasn’t been selected out because of how easy it has become to live, and to pass on our genes. Selective pressures have dropped considerably for our species, to such a point that minute influences such as these are fairly meaningless now.

Another Possibility

Of course, this explanation doesn’t solve our original question: what prompted those dolphins to save the human swimmers. In the Red Sea example, the human swimmers first swam with the dolphins before the rescue occurred. This may have been crucial; for dolphins, swimming and playing is used to strengthen ties within a social group. It is possible that by engaging in this play the humans included themselves in the group, and thus had the dolphins protective instincts extend around them also. The same might be true of the New Zealand example. Although no prior swimming occurred in that particular incident, swimming with bottlenose dolphins around the North Island is regular, and its quite possible that those bottlenose dolphins had previous experience with humans, so at least a social connection with others of our species.

A thoroughly interesting topic. On a more somber note, I invite you to read about our mixed relationship with these animals.

References

Written by Tom Bates