Researchers at Stony Brook University have developed a model to estimate how long evolutionary forces would take to restore natural balance among mammalian communities plagued by extinction.

For the Caribbean's New World leaf-nosed bats, the most varied and diverse bat family, the process would take at least 8 million years.

Since the arrival of humans, dozens of Caribbean bat species have gone extinct. Over the last 20,000 years, a third of all bat species across the Greater Antilles have disappeared.

It's difficult to determine whether or not -- or to what extent -- humans are responsible for these extinctions. To quantify the influence of human colonization on bat extinctions, Liliana Dávalos, a professor of ecology and evolution at Stony Brook, developed biogeographical models.

Dávalos and her colleagues used a wealth of paleontological and evolutionary New World bat data -- including data on both living and extinct species -- to build the models. Their work revealed an equilibrium of biodiversity for millions of years prior to the arrival of humans, and allowed researchers to simulate how long it would take natural forces to reinstate equilibrium sans human interference.

"Remarkably, it would take at least 8 million years to regain the species lost," Dávalos said in a news release. "This incredibly long time required to restore diversity reveals the staggering consequences of extinctions, many caused by humans, on the long-term ecology of islands."

Dávalos and her researcher partners detailed their new model in the journal Nature Ecology & Evolution.