Elephant warfare: These tusked warriors stopped Alexander the Great, but at great cost

Elephants in India suffered population bottlenecks 100,000 years ago and then 2,000 years ago. Scientists believe the most recent event was because they became animals of war and helped stop the Macedonian conqueror in his tracks

Evolutionary scientists have found that Indian elephants faced a population bottleneck nearly 2,000 years ago that lasted 1,500 years. This drastic reduction in population was not the result of an epidemic or the environment or of migration, but was mostly the wages of war. Elephants were, once upon a time in India, used for warfare; even Alexander of Macedonia had to stop his eastward expansion due to elephant armies.

Historical accounts show that populations of elephants in ancient India were caught and used in warfare from prior to the Mauryan Period (321 to 185 BCE) until a little before the Mughals, around 500 years ago. Ancient Greek sources suggest that King Chandragupta Maurya (4th Century BCE) had anywhere between 3,000 and 6,000 elephants. 

Male elephants were captured young and they missed the freedom and food, and died in captivity, say writers. Their populations could have reduced because of huge numbers of elephants dying in battles until the population hit a bottleneck.

“This seems to be a pattern in that populations can hit bottlenecks in the timeline of elephant history,” says ecologist Raman Sukumar at the Centre for Ecological Sciences in the Indian Institute of Science (IISc) in the southern city of Bangalore. 

As Uma Ramakrishnan, a molecular ecologist at the National Centre for Biological Sciences puts it, “It could have been an epidemic that killed them but historical records do show that warfare is a more probable cause.” 

Due to favorable conditions of –probably– climate, high birth rates and lower death rates, numbers revived again and led to a population divergence.

A documentation of the use of war elephants in ancient India is a sculpture in the Channakeshava Temple in the 13th century Hoysala temples of Beluru, located in the south India state of Karnataka. It shows the  four wings of ancient armies in India: infantry (elephant), cavalry (horse), foot soldiers, and chariotry. This chaturanga bala or chaturanga sena (the fourfold army) is a recurring feature in Indian history and literature.

The mythological epics Mahabharata and Ramayana mention the use of elephants in war, says Sukumar in his book ‘The Story of Asia’s Elephants’. He also describes in detail the battle of Hydaspes between Alexander of Macedonia and the Indian king Puru, and how the 80 or more elephants fielded in the latter’s army killed friend and foe alike. 

Even though Alexander and his army won this battle, they later abandoned their conquest of India and  went home when they heard that more powerful kings further east possessed much larger numbers of elephants in their armies. As Sukumar puts it: “One not inconsiderable factor which forced Alexander to break off his incredible march of conquest was the elephant.” 

The same book says the 300-year-old early history of the elephant in the Mediterranean culminated in the end of this animal as a war machine in this region by the time the Christian faith began to spread from the Holy Land. Romans did sometimes deploy the elephants that they captured from wars but also used the animal in public spectacles, for entertainment in circuses and amphitheaters, and for ceremonial processions. 

Romans had no real means of acquiring elephants directly from India; the few Indian animals they possessed were captured from their enemies but, by the time Rome became the imperial power in the region, the culture of the war elephant had faded. Just like King Puru had Ajax, the elephant to face Alexander and Hannibal had Surus in his march to the Romans, the Sinhalese King Kavantissa had the war elephant, Kandula. 

Historian Thomas Trautmann writes in ‘Elephants and Kings’, his environmental history of elephants in Indian kingdoms, that the use of elephants for war was influenced by the arrival of Aryan people in India, bringing their culture of horseback riding into a land with no horses but lots of elephants, and how the animals' upkeep by kings ultimately led to preservation of forests as resources for fodder.

A recent study by Sukumar, Anubhab Khan, from the same center at IISc, Ramakrishnan and others has shown signatures of population bottlenecks in Indian elephants around 100,000 years ago. What struck them, however, was the above-mentioned bottleneck which began about 2,000 years ago, lasted for about 1,500 years. They cautiously suggest that this population reduction in historical time, reported for the first time, may be related to the large-scale capture of elephants for warfare. 

The researchers use sophisticated statistical methods to rebuild demographic history from genetic data, in this case around more than 30 elephant genomes were sequenced throughout India and genetic signatures were used to build the demographic history of elephant populations in India. 

The study raises interesting questions about whether the use of elephants in war some 1,500 years ago is partly responsible for their population structure today.

“Evolution in population genetics is measured in five ways,” Khan says. “They are bottlenecks, migration, mutation, natural selection and inbreeding among relatives. The significance of a bottleneck is that it is evidence of evolution.” 

Disease in a population due to a hereditary trait could lead to death in elephants or fewer babies and the defective gene is removed. "Similarly, a bottleneck causes a reduction in population which reduces genetic diversity and leads to a loss of rare genetic variations,” Ramakrishnan feels. “We will try working on more elephant populations in future.”

As an analogy, according to Khan, what if there were two isolated populations of say, tigers in Ranthambore, Rajasthan (in Northwest India) and another of tigers 2,000 kilometers away in Wayanad, Kerala (in South India) and they lived independently of each other? There is no mating between the tigers of Ranthambore with the ones in Wayanad. There is restricted gene flow, therefore. If this continues for millions of years, a macro evolution could lead to the tigers turning into different species. On a short scale of evolution, it can be measured by the above evidence of which a bottleneck is of significant value. 

Sukumar provided an interesting example of recent evolution among male Indian elephants. He told RT: “Both tusker males and makhanas, which are tuskless males, exist in nature. There are much higher numbers of makhanas in the Northeast than in the South, possibly the consequence of the selective capture of tusked male elephants for use in war over historical time."

On the other hand, he noted, the very recent increase in makhanas in southern India is due to "selective pressure for elephant tusks" in a region where the notorious poacher Veerappan was known to live. "Our next step is to hunt for genes that are involved in tusk expression.”