Heightened awareness of the danger of viruses to ourselves and to other forms of life brings up again the question of origins. How did structures little more than packages of genes, come about, and how did they manage to come up with the genetic material necessary to command an infected host to reproduce them? The most commonly accepted hypothesis is that viruses have evolved from escaped bits of the genetic material of other organisms, some by chance having the necessary genes.
This is not the only possibility, however. We know that many parasites
have evolved to become almost entirely reliant on their hosts, losing parts and
processes no longer needed. Indeed, some internal parasites consist of little more than
reproductive structures and the minimal tissues required to support those organs.
It's been suggested that viruses began as parasites that have gone the ultimate
distance in that direction, managing to shed even reproductive organs by evolving the
ability to take over the host cell to reproduce themselves. Natural selection is not
only fascinating, at times it's downright scary!
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.