London: Researchers have created the first estimate of how the world's mammal diversity map would have appeared if modern man had never existed.
In a world without humans, most of northern Europe would probably now be home to not only wolves, Eurasian elk (moose) and bears, but also animals such as elephants and rhinoceroses.
The current world map of mammal diversity by a team from Aarhus University in Denmark shows that Africa is virtually the only place with a high diversity of large mammals.
However, the world map constructed for the natural diversity of large mammals shows far greater distribution of high large-mammal diversity across most of the world, with particularly high levels in North and South America, areas that are currently relatively poor in large mammals.
“Northern Europe is far from the only place in which humans have reduced the diversity of mammals -- it's a worldwide phenomenon. In most places, there's a very large deficit in mammal diversity relative to what it would naturally have been,” explained professor Jens-Christian Svenning, one of the researchers behind the study.The natural diversity of large mammals as it would appear without the impact of modern man (Homo sapiens). The figure shows the variation in the number of large mammals (45 kg or larger) that would have occurred per 100 x 100 kilometre grid cell. The numbers on the scale indicate the number of species (Illustration: Søren Faurby)
In a previous analysis, the team has shown that the mass extinction of large mammals during the Last Ice Age and in subsequent millennia (the late-Quaternary megafauna extinction) is largely explainable from the expansion of modern man (Homo sapiens) across the world.
In this follow-up study, they investigated what the natural worldwide diversity patterns of mammals would be like in the absence of past and present human impacts.
Most safaris today take place in Africa under natural circumstances as many or even more large animals would no doubt have existed in other places.The current diversity of large mammals. It can clearly be seen that large numbers of species virtually only occur in Africa, and that there are generally far fewer species throughout the world than there could have been. (Illustration: Søren Faurby)
“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,” informed post-doctoral Fellow Soren Faurby and the lead author on the study.
The existence of Africa's many species of mammals is thus not due to an optimal climate and environment, but rather because it is the only place where they have not yet been eradicated by humans.
Today, there is a particularly large number of mammal species in mountainous areas.
“The current high level of biodiversity in mountainous areas is partly due to the fact that the mountains have acted as a refuge for species in relation to hunting and habitat destruction, rather than being a purely natural pattern,” the authors noted in a paper published in the scientific journal Diversity and Distributions.
The new study can provide an important base-line for nature restoration and conservation.