The study "shows without any significant doubt that we are now entering the sixth great mass extinction event," said co-author Paul Ehrlich, a Stanford University professor of biology.
And humans are likely to be among the species lost, said the study -- which its authors described as "conservative" -- published in the journal Science Advances.
"If it is allowed to continue, life would take many millions of years to recover and our species itself would likely disappear early on," said lead author Gerardo Ceballos of the Universidad Autonoma de Mexico.
Remember the mass-extinction event that wiped out the dinosaurs? Earth is apparently on the verge of another great biological extinction, and humans are solely to blame.
Scientists have previously classified five large-scale losses of animal life as mass-extinction events, all of which occurred millions of years ago. In recent years, the planet has seen the loss of hundreds of species of animals, and according to a new analysis from an international team, the planet may be in the early days of its sixth mass-extinction event.
As part of the study, researchers analyzed previous studies and scientific data to draw their conclusion that human activities and population surges worldwide -- not a catastrophic event, like an asteroid impact, for example -- are responsible for the drastic decline of animal life. Lead author Rodolfo Dirzo, a biology professor at Stanford University, cites actions like overexploitation of resources and habitat destruction as examples of harmful human activities.