individual, suggesting that the society of these ancient creatures was sexually segregated like today’s elephants, with independent males usually walking separately from the family group. The social patterns seen in today’s elephants stretch back millions of years into evolutionary history.
Around 5 million years ago there was another enormous transition on our planet as the earth became cooler and dryer. The forests began to shrink further, while deserts and grasslands got bigger. As a result, the availability of good quality food for large herbivores declined and those that could not adapt went extinct. Large body size (and perhaps large brain size) was an advantage, because bigger animals can eat more low-quality food to get their daily nutrients and energy.
Then, about 2 million years ago at the start of the Pleistocene epoch, another period of rapid climate change saw the earth cool even further. Elephants were forced to adapt yet again. Glaciation meant that some species became isolated and others were squeezed into areas that were already being inhabited by other animals. Fluctuating sea levels even led to some elephants becoming trapped on islands.
Being large is typically unnecessary on islands without predators, because there is no need to waste time and energy growing big to avoid being eaten, when there is no one to eat you. So, many island elephants underwent rapid and radical shrinking (rapid in evolutionary terms, at least). One such species, the
Cyprus dwarf elephant – a straight-tusked species that became extinct around 13,000 years ago – weighed only 200 kg and was the size of a large dog.
Despite their huge success, with a considerable evolutionary history and the fact that they could be found almost all over the world, there was a sudden and dramatic extinction of proboscideans at the end of the Pleistocene, between 15,000 to 10,000 years ago. Mastodons, gomphotheres and mammoths all died off at an unprecedented rate. Only one small population of woolly mammoths survived much longer. They remained isolated on the Wrangel Island of Siberia until 4,000 years ago, which is remarkable, because by that time the pyramids of Egypt had already been built!
It wasn’t only proboscideans who suffered during this period. Thirty-five groups of large mammal became extinct in North America alone, including the giant sloths, sabre-toothed tiger and the American cheetah. Before these extinctions, the diversity of mammal species in the Americas exceeded that of modern-day Africa.
Two main ideas have been put forward to explain these sudden declines. The first suggests that, as had happened before, rapid climate change altered vegetation to such an extent that large herbivores and their predators could not adapt quickly enough and died out from starvation. The second, equally grim hypothesis suggests that this period saw the emergence of a super-predator, which used its superior intelligence and employment of tools to kill off the big beasts. That predator was, of course, us: modern humans armed with Stone Age technology.
Increasingly, the evidence points an accusatory finger towards us. Either way it’s hard to brush off as coincidence that this cascade of extinctions took place over a remarkably short time period – a few thousand years. As the ancestors of modern humans evolved in Africa and migrated in successive waves across Eurasia, large mammals would have experienced varying levels of exposure to this new predator, depending upon where they lived.
African mammals co-evolved with hominids (the great apes, which includes us) and were slightly better adapted to dealing with our ancestors. Better hearing, smell, and an innate fear of people, perhaps. Species in Australia and the New World, however, were caught completely unawares by our sudden arrival, and were much more vulnerable.
When we look at changes in the distribution of plants and animals over time, the large mammal extinctions correlate almost perfectly with the arrival of modern humans. Those species that had the least time to adapt to the arrival of man were the most likely to die out.
There is even some evidence that mammoths were the preferred targets of early human hunters. It makes sense: killing one of these enormous beasts would provide a huge amount of meat for a hunter-gatherer family, which made the effort and risk of hunting them worthwhile. But, as prehistoric cave art depicting them shows, mammoths provided more than simply meat. Ivory is a much better material than deer antler for making the spear and arrow points needed for big-game hunting, so the ivory of slain mammoths was used to hunt more effectively and kill even more mammoths and other megafauna.
Climate change almost certainly played some role in driving a number of extinctions, but this is increasingly believed to be a secondary factor in the collapse of large mammals. South America suffered some of the greatest losses, yet the climate there was far more stable than in Africa, which experienced comparatively few megafauna extinctions over the same period.
Many of the large herbivore species that went extinct were generalist foragers, who could eat grass or browse for food depending on availability. All the evidence suggests that there were still plentiful foraging opportunities, and some species, such as the American mastodon, went extinct even though their preferred plant species have remained abundant up until present day. The only viable culprit for these mass extinctions appears to be the human race.
Human pressure on animal populations. Man’s desire for ivory. Climate change. This all sounds eerily familiar. We – or at least our ancestors – have to hold up our hands for the dramatic decline in the number of proboscidean species existing in the world, a decline that continues, and now encompasses the remaining members of that family.
One thing that can help us to understand elephants better is having an idea of where they lived and how far they ventured – their range and spread. It is difficult to know the exact prehistoric ranges of elephants, but we do know that the ancestors of both the African (Loxodonta) and Asian (Elephas) species lived together in Africa for a very long time.
Even after the latter species spread out of Africa into the Middle East and across Asia, some stayed behind until as recently as 11,000 years ago.
Understanding the movement of elephants over the last few thousand years is a challenge, but we can use rock art – like those etchings found in Libya and Sudan – and descriptions from ancient texts to give us some clues. From these historic sources, one thing is readily apparent: until very recently, elephants roamed over most of the African continent, all the way from the Mediterranean coast in the north to the beaches of South Africa.
They spread from the jungles of Senegal in the west, to the highlands of Ethiopia in the east. They inhabited every kind of African environment, from the arid deserts of Namibia and the fringes of the Sahara, all the way up to the treelines of Africa’s great peaks. Savannah elephants wandered the slopes of Mount Kilimanjaro and the Rwenzoris, while their forest cousins bathed in the Congo river.
Aristotle spoke of elephants wandering the Atlas Mountains near the Strait of Gibraltar in modern-day Morocco, and Pliny the Elder reported that herds of elephants ‘infested’ parts of modern-day Libya and Algeria. But by around AD 500, there were no wild elephants living in Mediterranean north Africa.
It has been predicted that up until the sixteenth century – before European exploration, exploitation and colonisation really took hold – there could have been more than twenty million elephants in Africa. This staggering figure is an estimate, based on our understanding of how much space was available for elephants, and how many elephants each of these areas could have supported, given the vegetation they likely contained.
What is certain is that from the moment Europeans arrived, the
