According to one study, nature will need five million years to fill the gaps caused by massive extinctions of human origin.

Humanity has brought the world to the brink of mass extinction that could eliminate vast expanses of life on Earth for millions of years, scientists said in a new study.

The work suggests that humans kill animal and plant species so quickly that evolution is unable to keep up with the gaps left behind.

According to the researchers, unless conservation efforts are intensified, it will take between three and five million years for nature to recover the levels of biodiversity that should be lost over the next 50 years.

There have been five massive extinctions over the past 450 million years, and scientists have warned that climate change, poaching, pollution and habitat destruction are causing a sixth.

According to researchers from the Aarhus University in Denmark and the University of Gothenburg, more than 300 species of mammals have been eradicated by human activity. Others may follow them to extinction in the coming decades.

The team studied the impact of humankind on nature using a large database of living species as well as those that have become extinct in the relatively recent past as a result of the spread of humanity in the world.

With the help of advanced simulations, researchers estimated how long it would take for evolution to fill the gaps in biodiversity after extinctions.

Instead of simply counting lost or threatened species, the study took into account the time spent by each to evolve. The extinction of species with distinct lineages and few close relatives resulted in the loss of "unique ecological functions and the millions of years of evolutionary history that they represented", said the researchers.

"Large mammals, or megafauna, such as giant sloths and saber-toothed tigers, which have been extinct for about 10,000 years, were very distinct from the point of view of evolution," said Matt Davis. paleontologist from the University of Aarhus, who led the study. "Since they had few close relatives, their extinctions cut off whole branches of the Earth's living tree."

Researchers have suggested that conversations about endangered mammals with a long history of evolution should be prioritized.

They highlighted Asian elephants, one of only two species of a once mammoth order of mammoths and mastodons, which would have only a 33% chance of surviving the century.

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"data-reactid =" 16 ">" There are hundreds of species of shrews, which allows them to withstand some extinctions, "said Mr. Davis. There were only four species of saber-toothed tigers; they have all disappeared. "

Professor Jens-Christian Svenning, also from the University of Aarhus, added: "Even if we lived in a world of giants – giant beaver, giant armadillos, giant deer, and so on. – we live now in a world increasingly poor in large wild mammals. .

"The few remaining giants, such as rhinos and elephants, may disappear very quickly."

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Even if humans stopped completely behaving in a prejudicial way and extinction rates returned to normal, it would be between five and seven million years before biodiversity returned to the way it was before. the advent of man.

Tony Juniper, executive director of advocacy and campaigns at WWF-UK, said the study was "another warning sign that our world is in crisis".

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"As we shred the web of life, unique animals and plants that have evolved in different ecosystems are disappearing forever."

Fundamental changes in the natural world could have disastrous consequences for humanity, Juniper warned.

"We must urgently put an end to this loss of natural diversity, not only because of the importance of wildlife for its own benefit, but also because human societies are as deeply rooted in this web of life as tigers, bumblebees and primroses, "he said.

"The more we damage the natural fabric, the more we jeopardize our own future."