[BMCDA]

Well, just because a system is stable doesn't mean it cannot change. Depending on it's flexibility it accomodates faster or slower to changing conditions. However, if this change is too fast and/or too dramatic the system becomes unstable and breaks down.
You can observe this during catastrophic events where some populations simply cannot adapt to the new conditions and die out whereas others survive, although not without heavy losses.

[AndrewC]

Well, just because a system is stable doesn't mean it cannot change. Depending on it's flexibility it accomodates faster or slower to changing conditions.

But that is a point I made. The stable configuration does change, but it remains stable. That means that everyone is dragged along and follows the stable point.