Poison

Most of us are aware of what happens when we eat or drink something that is tainted - it's not long before our entire physiology is out of place and we're in need of removing the said corruption from our bodies rapidly.
What happens when it isn't that sudden, though?
What if we were gradually poisoned, or if the dreadful material was introduced to us in such a way that our bodies initially accepted it as good - which is what happens in measure with the chemistry of some types of virus?
The consequences are more gradual, but the results are usually far more fatal.

In the 1850s, Charles Darwin published his findings that pointed to the notion that life is essentially a random series of accidental events that eventually resulted in human beings. He was personally reluctant after publishing to really push the notion loudly, but pretty soon, a pro-evolutionary 'bulldog' appeared in the form of one Thomas Huxley, who made sure that the notions Darwin had presented in Origin of the Species became essential to the culture of the West (See Michael Denton's excellent work, Evolution - A Theory in Crisis).

The consequences of this are now being played out in the nuts and bolts of what is happening in our world.
Here's a discussion on those current events, and how these underlying concepts of meaninglessness are being played through.