My brother recently acquired a kitten. Both my brother and his doting black Labrador, Dusky, are completely bemused by this new addition to the family. Already, at two months, Masty (short for Mastodon, named because he was the biggest and rowdiest in his litter) is ruling the roost. The image (at right), exemplifies the difference [...]

The Sunday Times Sri Lanka

Living together: A lesson from the animal kingdom


Cats vs. dogs (Source: cats-vs-dogs.html)

My brother recently acquired a kitten. Both my brother and his doting black Labrador, Dusky, are completely bemused by this new addition to the family. Already, at two months, Masty (short for Mastodon, named because he was the biggest and rowdiest in his litter) is ruling the roost. The image (at right), exemplifies the difference between him and Dusky.

Solitary animals — like Rudyard Kipling’s ‘The Cat that Walked by Himself’ — live most of their lives alone, and only ‘socialise’ during the mating season or when a female has offspring. They usually carve out territories for themselves, and feed, hunt or escape from being hunted, sleep, and generally carry out their daily activities within these territories, defending these areas from entry by individuals of the same species. Wild cats, with a few exceptions, are solitary.

In contrast, social animals live in groups, sometimes forming elaborate societies.

The simplest form of social grouping is a temporary aggregation. This may be in response to a stimulation — for example, the reduction in the length of a day, which is one of the stimuli for migration in birds.  When this stimulus is triggered, birds flock, and fly southwards in search of warmer climes. Sometimes these flocks, for example, such as those of the common starling, can be two million strong.

Another stimulus for temporary aggregation is mating. In some instances this does not involve a single male or female, but instead swarms of individuals. One of the most extreme forms of such an aggregation is seen in the Tisza mayfly (Palingenialongicauda) found in the Tisza River in Serbia and Hungary. Eggs are laid on the surface of the river and they sink and mature in about 45 days, but the larvae remain and grow in the mud for as long as three years, and then turn into adult mayflies. Millions of Tisza mayflies emerge in a synchronised event as one reporter writes ‘ as huge clouds’ from the river, and have just about three hours to live in which to mate, before they die. This materialisation of the mayflies from the Tisza River is called the Blooming of the Tisza.

Other animals live solitary lives, but collect communally to nest. Examples of communal animals include orangutans and tarsiers of Southeast Asia.

Yet others live in colonies. These animals nest or roost in large numbers at a specific location.  For example, some 402,571 black-browed albatrosses nest in the Falkland Islands, at a density of 70 nests per 100 m2. Many bats are also colonial.

Then, there are species which not only exhibit communal living, but also cooperatively care for their young, and show some distinction between who does and does not reproduce. In wolf packs,the pack is like a family — parents and their offspring from many litters.In lion prides, there may be up to three males and about 12 related females and their offspring. The females care for these cubs cooperatively, and even nurse each other’s cubs. The males defend the pride from other males. Females also hunt together.

Elephants live in matriarchal groups. Herds are led by the oldest and biggest female, and comprise many related females and their offspring.  Elephants communicate extensively, look after each other’s calves, find food together, and collectively protect their young.

However, the most elaborate form of social grouping in animals is found among ants and termites which are termed eusocial (‘truly social’). Here, there is a caste system — with a queen and her consort solely responsible for reproduction;sterile workers who clean the nest, find food, look after the young; and sterile soldiers who defend the nest from intruders.

As interesting as these examples are, much more interesting is why social behaviour has evolved.

In the simplest form of social grouping — aggregations, such as flocks — the obvious benefit is the advantage of avoiding predators.  Species that aggregate gain strength and security by sheer numbers.  If there are ten birds in a flock and a predator comes along, given that all other factors are equal, each bird has a one-in-ten chance of being caught and eaten by the predator.  Multiply the flock number by ten and it becomes apparent that the chance now decreases to one chance in a hundred. If there are a million birds, the chance of any single bird being eaten by the predator is a mere one in a million.

Similarly as the old adage says ‘many hands make light work’, many eyes and ears will spot danger more easily. This increased vigilance from many individuals results in a decrease in the amount of time spent by each animal looking for predators and in more time feeding.

There is also the ‘confusion factor’: fish are well known for a stunt they pull when attacked by a predator that is called the fountain trick. When a predatory fish swims at a shoal of fish, in a flash of a second the shoal splits in two and swims outwards and towards the back of the predator in the shape of a fountain, grouping again behind the predator.  This confuses the predator.

The corollary is also true. Hunting lionesses often confuse prey: one lioness makes a mock charge and the prey flee in another direction straight into the jaws of another female.

However, when one considers the alarm calls of deer (made when a predator is around), cooperative care of young, delaying or giving up reproduction in order to help another, the benefits become less clear. In Darwinian terms, what would one animal benefit by helping another, instead of getting ahead in the race for the survival of the fittest? What is the purpose of this seeming altruism?

Empirical data have shown that social animals do not help just anyone, but mainly their relatives. And this changes the picture, as relatives carry the same genes.  The evolutionary biologist J. B. S. Haldane, when asked whether he would lay down his life for his brother, famously replied ‘For two brothers, or eight cousins’ quantifying the genes we share with our relatives.

This ‘selection’ of relatives in the act of altruism is called kin selection.  Kin selection explains, in Darwinian terms, why altruism in animals makes sense.  In helping their relatives, individuals are, in fact, helping to pass their genes on to the next generation.

But what about examples where social animals help animals who are not their relatives? Vampire bats feed on the blood of other mammals. It is common that a foraging bat may not be able to feed each night. This is dangerous as these bats cannot live for more than a couple of days without food.  Bats who have fed, regurgitate their bloody meal so that others can feed. Again, this alone does not make sense in a Darwinian context, but observations have shown that such favours are returned, exemplifying the biblical quotation ‘Do to others as you would have them do to you.’ This form of altruism has been dubbed reciprocal altruism. (I must emphasise here that the term altruism, as applied in biology, must not be compared to the altruism that we, humans, refer to in our societies. As is stated in a dictionary of philosophy altruism in the context of animal behaviour is just ‘delayed self-interest. )

Many of the animals described above have not escaped from the destruction that humans are wreaking on the Earth.  For example, the Tisza mayfly is found currently in the Tisza River and its tributaries.  However, in the past, they were found in many of Europe’s lowland rivers. Scientists are convinced that this disappearance is a consequence of pollution from industries and engineering of riverbanks.

The biggest threat to Asian elephants is habitat loss and fragmentation. In the past, most of our island had thick forest cover and this allowed elephants to roam freely, feed wherever they wanted and take long walks in search of water. At the beginning of this century, nearly three- quarters of the island had forests. Now less than a quarter is forested. As a result, the elephants’ natural habitat has become fragmented. Now, when elephants move in search of water and food, they encounter human habitation with the invariable consequence of conflict.

Lion prides are not only affected by habitat loss but also by hunting and poaching, again because of conflict.

In the case of gorillas, which are affected by the threats listed above, there is the additional threat of disease.  Gorillas are closely related to humans and share many diseases. It is reported that Ebola outbreaks in Africa may have killed as much as 25% of the world’s gorilla population.

The problem with animals that live in groups is that often, when one is affected by some threat, so are the others. What could kill off one solitary animal, could decimate an entire group. At the other end of the scale, in an inter-species context, the most selfish of all species are humans.  We have seen off to oblivion many species; we have destroyed, damaged and degraded large swathes of ecosystems and habitats in order that we may ‘develop’ our cities and roadways and other infrastructure. In addition, we have killed off large numbers of our fellow humans while warring with each other. (It is reported that 108 million people were killed in wars of the twentieth century.)

Perhaps we humans should turn to the animal kingdom to learn how to live in peace with one another.

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