I was thinking antibiotics and vaccines but what we are doing to our planet because of overpopulation changed my mind.
Kind of a mixed bag there.
I can't help but think of any system in terms of an op-amp with or without negative feedback.
We're hardwired to favor positive feedback:
Push your gas pedal.
Car goes faster.
"Ooh, faster is good. I want to go even faster!"
Push gas pedal more.
Eventually the system reaches an unstable peak.
Negative feedback ensures that the system doesn't grow too quickly and become unstable: Ease up on the gas pedal as your speed increases, realizing that maxing out your engine isn't a good long-term solution.
Reproduction: Nature seems to assume that there's no problem that can't be solved by making more of a life form. It's a good survival tactic: If there's abundant resources, reproduce as quickly as your biology will reasonably allow. Your population will then likely spread out over a large geographic area. When the good times end, you might lose 95% of the resulting population, but now you have greater geographic diversity. The species as a whole has a greater chance of survival.
We usually place more value on individual well-being, but that instinctual drive still remains. The negative feedback is largely gone though: Major predators are mostly gone, diseases can be prevented and treated more easily, and deaths during childbirth are low. (At least in the first world, for the latter few of those.)
If we're talking about analyzing a system, this one has many characteristics of one that is not under control due to insufficient negative feedback.