Earth is 'in the middle of mass extinction'

Posted by Emma Woollacott

You may not have noticed, but according to an Australian academic, we're currently in the middle of a mass extinction event comparable to that which killed off the dinosaurs.

Macquarie University palaeobiologist Dr John Alroy says it's caused by a range of human behaviours and activities, along with climate change.

And he predicts major changes to the rules of evolution as we currently know them, which could have devastating consequences for future biodiversity.

Alroy studied data from nearly 100,000 fossil collections worldwide, tracking the fate of major groups of marine animals throughout the fossil record, and espeically during the Earth's most massive extinction event, 250 million years ago.

He concluded that while we've assumed the rules governing diversity of these major groups to be invariant, they have actually changed over geological time.

Thus, a group's average rate of diversification or branching into new species in the past is not a good predictor of how well it will fare after a future mass extinction event.

As a result, he says, the major extinction event currently underway will be much more severe than most - indeed, he says, there have been only three mass extinctions on the level of the current one in the last half billion years.

Organisms that might have adapted in the past may not be able to manage it this time, he says.

"You may end up with a dramatically altered sea floor because of changes in the dominance of major groups. That is, the extinction occurring now will overturn the balance of the marine groups."

Alroy likens what is happening now to rolling the dice with evolution.

"What's worrisome is that some groups permanently become dominant that otherwise wouldn't have," he says. "So by causing this extinction, we are taking a big gamble on what kind of species will be around in the future. We don't know how it will turn out. People don't realise that there will be very unpredictable consequences."