An emerging debate in the world of natural sciences: Are "invasive species" really that bad? 

The reasons to fight invasive species may be economic, or conservationist, or just practical, but underneath all these efforts is a potent and galvanizing idea: that if we work hard enough to keep foreign species from infiltrating habitats where they might do harm, we can help nature heal from the damage we humans have done to it as a civilization.

In the past several months, however, that idea has come under blistering attack. In a polemical essay that appeared in the leading science journal Nature in June, a biologist from Macalester College in Minnesota named Mark Davis led 18 other academics in charging that the movement to protect ecosystems from non-native species stems from a “biological bias” against arbitrarily defined outsiders that ultimately does more harm than good.