What the World Would Look Like If Humans Hadn't Killed All the Animals
Wildebeest in Masai Mara, Kenya. Image: Carl De Souza/Getty


This story is over 5 years old.

What the World Would Look Like If Humans Hadn't Killed All the Animals

If it weren't for the ascent of mankind, the entire world would still look like the Serengeti, a galloping, roaring, thunderous paradise.

An African safari represents the highest form of interaction with terrestrial giants remaining in the world. The smell of sunlight on acacia leaves and sprawling vistas of ancient beasts going about their daily dramas invoke sublime memories of our shared past and an uneasy feeling of recognition. You somehow feel that you have been here before.

The largesse of wildlife available in Africa is largely limited to that continent, but what if it wasn't? Imagine a Europe where mammoths and woolly rhinos roam northern Scandinavia, Iberian wolf packs hunt aurochs and brown bears swagger through the Dolomites. If it weren't for the ascent of mankind, the entire world would still look like the Serengeti, a galloping, roaring, thunderous paradise of bloodshed and birth, terror and triumph, as a recent study spells out in living color.


"The fact that the greatest diversity of large mammals is found in Africa reflects past human activities, and not climatic or other environmental constraints," said lead author Dr. Søren Faurby, an evolutionary biologist from Aarhus University, Denmark, who is now with the Museum of Natural History in Madrid.

Modern Africa is the last stand of the megafauna that without humans would still cover the planet—a besieged refuge now witnessing the death throes of these final survivors of a world before us.

In a recent interview, Faurby told me that his paper, published in Diversity and Distributions, affirmatively "showed that the results strongly suspect a human causation of the extinction of the megafauna. As part of this paper me and [co-author] Jens-Christian Svenning attempted to figure out where these extinct species would have been today if they did not go extinct."

Projected diversity of large mammal species (>45kg) across the world if humans did not exist. Red areas are more diverse. Image: Soren Faurby

According to Faurby, this is the "first estimate of how the mammal diversity world map would have appeared without the impact of modern man." The research is a data-driven portrait of mammalian species, both living and those that went extinct within the last 130,000 years, as they would be naturally present across the landscape if humans had never arrived to throw a wrench in the works.

The study makes amply apparent the extent to which we have impoverished the world during our brief existence on it. Dr. Svenning, a biologist with Aarhus University, said that "Northern Europe is far from the only place in which humans have reduced the diversity of mammals—it's a worldwide phenomenon. And, in most places, there's a very large deficit in mammal diversity relative to what it would naturally have been."


The world maps assembled by the researchers graphically illustrate how things would look absent our merciless predatory instinct, with much greater distribution and diversity of large mammals across most of the planet. Note the extraordinarily high levels in both North and South America, continents that today are relatively drained of large mammals—the few wolves and grizzly bears we've allowed to live as scattered survivors would be dominant predators across most of the West, pursuing camelids, bison and giant ground sloths across a Great Plains without a grain silo in sight.

"Most safaris today take place in Africa," Faurby said, "but under natural circumstances, as many or even more large animals would no doubt have existed in other places, notably parts of the New World such as Texas and neighboring areas and the region around northern Argentina and southern Brazil. The reason that many safaris target Africa is not because the continent is naturally abnormally rich in species of mammals. Instead it reflects that it's one of the only places where human activities have not yet wiped out most of the large animals."

Current measured diversity of large mammals. Yeah, it's a lot less. Image: Soren Faurby

Of particular note here is the loss of enormous terraforming and nutrient cycling capacities of megafaunal mammals (those weighing > 44.5 kg), the earthly titans we extinguished thousands of years ago from almost everywhere but sub-Saharan Africa.

But even there the seeming richness is somewhat illusory, a shadow of what once existed. There are dozens of species of antelope in Africa, for instance, but only two African elephants: the familiar African elephant (Loxodonta africana) and the forest elephant of West and Central Africa (Loxodonta cyclotis). Seventeen of the nineteen species of the elephantine order Proboscidea went extinct during the late Pleistocene, the last Ice Age when modern humans erupted from Africa, leaving us with only the African and Indian elephants surviving today. Today, in Africa and southern Asia, there are a grand total of three species of survivors.


European colonists were dumbfounded by the biological richness of the Western Hemisphere, as indeed they should have been given the plundered paucity of the Old World since the Neolithic era's advent of agriculture and urbanization and the decimation of native ecosystems. But the splendor that greeted colonists in North America was still only an echo of its prehistoric condition, in which human activity and climate change both contributed to a collapse of Pleistocene megafauna.

Darwin posited that species compete with each other less when they're less related; those animals possessing similar anatomies, foraging patterns and habitats are more likely to spar over the same resources. Darwin's hypothesis can "also be seen by tabulating the diversity of different continents," Faurby told me.

"The megafauna of South America belonged to nine different orders, ranging from: Carnivora (carnivores) and Cetartiodactyla (a sprawling group of even-toed ungulates including cattle, deer, camels, pigs, goats and sheep) to Perissodactyla (odd-toed ungulates such as zebras, hippos and tapirs) and Proboscidea (elephant relatives)," he said. "This indicates a high level of biodiversity in prehuman South America, where many different mammalian orders could exploit a varied landscape without detrimental competition."

Today, Faurby continued, "the megafauna of Africa 'only' belong to six orders: Carnivora, Cetartiodactyla, Perissodactyla, Proboscidea, Tubulidentata (the aardvark) and the primates. It is possible that this lower ordinal diversity could potentially be a cause of why there is such high diversity in the New World."


It's like reassembling a puzzle with most of its pieces buried and forever lost

In other words, there are fewer different kinds of large mammal species in Africa today compared to prehistoric South America in the past because of interspecific competition for the same limited resources in modern Africa—limited due to human encroachment, land conversion and direct take in the form of hunting and, today, poaching and wildlife trafficking.

The team's analysis is remarkable for its bold approach to seeking out the true cost of our evolutionary ascension. Faurby points out that, "no previous study has systematically estimated the natural distribution of all species within larger clades [a clade is a taxonomic grouping that includes a common ancestor and all the genetic descendants, extant and extinct, of that ancestor]," making this study crucial for establishing baselines for modern conservation strategies. Like reassembling a puzzle with most of its pieces buried and forever lost, we can construct only a facade of an Earth that through the ages we've violently transformed into something more to our own liking.

Rewilding—the reintroduction of species, especially the big ones, that had been previously eradicated from an ecosystem—is thus a piecemeal form of evolutionary recovery from the millennia of exploitation that removed so much wild from the world. When informed by research such as this, rewilding efforts are granted a window into a lost world, paleontological proof of where animals suitable for reintroduction can best reestablish themselves according to the buried bones of their ancestors.


One finding of particular interest is a reappraisal of the presence of megafauna in mountainous regions. "Steep mountains may offer a refuge from humans, both prehistorically and today," according to the study. "Therefore, our results suggest that the positive effect of elevation range on the current diversity of terrestrial megafauna may be largely anthropogenic."

This older BBC documentary offers good background on megafauna diversity.

So while we may view the elk bugling in the Rockies and brown bears prowling the Urals as animals in their natural habitats, both species actually evolved in the open plains and taiga, and were forcibly relocated to higher elevations solely because of human pressure. Those species that did not adapt (rapidly) to this unprecedented variety of hunter upon its sudden emergence were extinguished.

But by creating an overlay depicting where things would be without our having evolved as we did, the authors offer serious conservationists a starting point from which to build some semblance of what should still be. And by knowing what species we've lost and where they had been, these scientists assert, we can better shape the rejuvenation of a world which, while no longer purely "natural," can at least approximate the ecological heritage looted by humans long ago.

Correction: An earlier version of this story misstated the number of elephant species and subspecies that have gone extinct. The number 175 refers to the number of elephantine species for the entire fossil record over 65 million years, not just the Pleistocene era covered in this story, which had only 19 species of elephantine mammals (elephants, mammoths, mastodons, etc.) when modern humans migrated out of Africa.