05 November 2004

Are Human Beings Weeds?

What is a "weed"? Generally it means a plant growing where it is not wanted. It is not the plant itself, but how it interferes with what we are trying to do with the environment that earns it the name of "weed". This definition is completely human-centered. The broader term "weedy species" applies to animals as well as plants.

But looked at another way, don't we humans ourselves have many of the characteristics of weedy species?

Characteristics of weeds and weedy species (as we humans have defined them):
  • They interfere with activities we value, such as the way we want our gardens to look, the production of crops and livestock at least cost, other economic activities, or our use of the environment.
  • They crowd out other species we would prefer to have at that site.
  • They crowd out native species already growing there.
  • They are directly toxic or otherwise bothersome to us (think of poison ivy).
  • They are costly or difficult to prevent or remove.
  • They tend to reproduce prolifically and occupy vacant or disrupted environments.
  • They are often versatile in terms of habitat, nutrition, and interaction with other species--flexible and adaptable.
  • Examples are rats and mice, or other species when introduced in new environments without their natural predators (dogs, prickly pear cactus in Australia)
Something that is a weed in one situation may be desirable elsewhere. Milkweed is an agricultural weed, and is toxic if eaten. But it is also the sole food of the larvae of monarch butterflies, which are highly esteemed. No milkweed plants--no monarch butterflies.

Those Pesky Humans!
  • They have invaded virtually every habitat on Earth except underwater zones (and will probably find a way to colonize Mars).
  • They can out-compete any other species that occupies territory they want or that threatens them.
  • They can reproduce rapidly when constraints of disease are removed by their technology.
  • They have become one of the dominant species on the planet in just a few thousand generations.
We're the kings and queens of the weeds! (Yes, there is a They Might Be Giants song on this subject. Download the video here.)

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