Having awoken in the middle of the night in a tussive fit the other night, I was having trouble falling asleep. Grogily, i contemplated the nature of viruses. What was the purpose of creating them? It's not like they're actual living beings that metabolize--they just float around and annoy their hosts. With my intellectual capacity diminished by my unquenched fatigue, this is what I came up with.

1. It's a way to control population. Perhaps viral infection and consequent mortality is a way of maintaing biospheric harmony. Say, when the bird population gets a little too high, avian influenza starts cutting them down. Or, with people, maybe it's the role of HIV. And, of course, killing their hosts too rapidly wouldn't be good either. Since viruses depend on their hosts for reproduction, it wouldn't make sense to just kill the hosts off so quickly. Instead, the hosts are destined to suffer through the torturous process of infection so that viral loads can multiple and the viruses can go on to infect others. After all, I guess it seems a little more natural than God randomly zapping people off the face of the earth.
2. God's just plain mischievous. I've often asked others why people create computer viruses and the answer is usually "because they can." I suppose that in itself isn't great reason--it could equally be used to explain why scientists make great discoveries and why dogs piss on fire hydrants. But I have always thought of it as mischief. And so with the same sense of mischief--wrought through His infinitely vast wisdom and omniscience--God created viruses.

Now, I must emphasize the dearth of lucidity when these thoughts were formed. It's not like I thought either of these options out thoroughly--nor that I cared to while half-asleep. Now if only I got better, then I wouldn't have to think about viruses at all...