A recently released study led by Matt Davis which appeared in the science journal PNAS and was reported at the wonderful ScienceDaily web site, finds that it will take 3 to 5 million years for evolution to replace the number of species going extinct— both animal and plant --— to current levels of biodiversity and 5 — 7 million years to get to the diversity levels that existed prior to the emergence of modern humans.
As reported at ScienceDaily,
The sixth mass extinction is underway, this time caused by humans. A team of researchers have calculated that species are dying out so quickly that nature's built-in defense mechanism, evolution, cannot keep up. If current conservation efforts are not improved, so many mammal species will become extinct during the next five decades that nature will need 3-5 million years to recover to current biodiversity levels. And that's a best-case scenario.
A particularly interesting aspect of the the study was a focus on finding those species which represent entire evolutionary branches.
The researchers used their extensive database of mammals, which includes not only species that still exist, but also the hundreds of species that lived in the recent past and became extinct as Homo sapiens spread across the globe. This meant that the researchers could study the full impact of our species on other mammals.
However, not all species have the same significance. Some extinct animals, such as the Australian leopard-like marsupial lion Thylacoleo, or the strange South American Macrauchenia (imagine a lama with an elephant trunk) were evolutionary distinct lineages and had only few close relatives. When these animals became extinct, they took whole branches of the evolutionary tree of life with them. We not only lost these species, we also lost the unique ecological functions and the millions of years of evolutionary history they represented.
This distinction and the data that led to it could have a bit of an upside if, of course, we could get our act together as a species,
The research team doesn't have only bad news, however. Their data and methods could be used to quickly identify endangered, evolutionarily distinct species, so that we can prioritise conservation efforts, and focus on avoiding the most serious extinctions.
As Matt Davis says: "It is much easier to save biodiversity now than to re-evolve it later."
Hope you enjoy the piece.