The debate over controlling invasive species raises the question of humanity's role in the world of nature.
Invasive species are an issue in North and South America due mainly to European colonization. Earthworms and honeybees are two early invasive species that aided our colonization of North America.
Most of the food we eat comes from invasive species, such as cattle, sheep, apples, wheat and a host of other animals we've brought with us.
There were lots of contributions the Americas made to the rest of the world, such as corn and potatoes, but generally we've brought along the plants and animals that produce the food we were used to eating.
Whenever a species is suddenly introduced someplace where it hadn't been before, it will cause a conflict.
When the isthmus of Panama arose from the ocean and allowed mammalian carnivores into South America, large numbers of interesting marsupial and avian carnivores perished.
Clearly, such beasts as the quagga or zebra mussel should be excluded from as many places as possible, if only to slow the damage they do.
But in many cases our attempts to pick which species to exclude is the other side of the coin that introduced them in the first place. In those instances, we are another force of nature, a role with which we are not always entirely comfortable.
