Adaptation is when the people or parts inside a system learn from what is happening to them and change their behaviour in response. A system does not just sit there and get acted on. It reacts, adjusts, and sometimes finds a completely new way to behave that nobody who designed the intervention expected.
This is a different idea from climate adaptation, which is about communities adjusting to a changing climate. Here, adaptation means something narrower and more general. Any system with people, or living things, in it can learn and change its behaviour in response to what is done to it, whether or not climate is involved at all.
This is closely tied to feedback loops, since watching how a system reacts to an intervention and adjusting your next move accordingly is really a feedback loop running through you as the practitioner, not just within the system itself. If you want a closer look at that idea, we wrote about it separately in Feedback Loop: What It Actually Means.
In 1995, the Mahila Housing Trust (MHT) launched the Parivartan Slum Networking Programme (SNP) in Ahmedabad as a collaborative model to upgrade informal settlements and provide basic infrastructure. Each household in the slum was asked to contribute ₹2,100 towards its infrastructure connection. The families living there were from low-income groups and did not have that sum of money or even a formal proof of residence to open a bank account and take a loan. But MHT didn’t change the rule. What changed, however, was how people met that requirement. MHT collected ₹100 at a time through SEWA bank accounts and helped residents use the papers they already had, such as electricity bills and municipal tax receipts, as evidence that they lived where they said they did. The people inside the system had understood what the rule required, and found a different way to behave in response to it.
Where You'll See It

The same pattern shows up in systems that have nothing to do with each other:
Bacteria and antibiotics. Give the same antibiotic again and again, and most bacteria die, but a few survive by chance and pass on whatever let them survive. Over time, the antibiotic stops working as well, not because the antibiotic changed, but because the bacteria did.
A scheme's eligibility rule. If qualifying for a benefit depends on owning a certain amount of land or earning below a certain income, some families will find ways to appear to qualify, splitting a landholding on paper or under reporting income, without their actual circumstances changing very much at all.
The One Thing People Get Wrong About It
It is easy to assume that if a rule or a target worked well the first time, it will keep working the same way every year after. Adaptation says something less comfortable. Once people understand what is being measured or rewarded, some of them will adjust their behaviour to look good against that measure specifically, sometimes without the underlying reality changing very much at all. A rise in an attendance register does not always mean more people are actually engaged. It sometimes just means people have learned what gets recorded.
A measure that worked well once is not guaranteed to keep meaning the same thing. The system reading it has had time to learn.
Key Takeaways
The rules of the game change as you play it. A system is not a fixed target. The people or parts inside it are watching, learning, and adjusting as your intervention unfolds.
Be ready to adapt your own approach in response. How a system reacts to what you have already done should shape what you do next, not just what you originally planned.
Notice the pressure your own intervention is creating. Any new rule, incentive, or measurement puts pressure on the people inside a system to respond to it, and that response is worth watching for on its own.
Expect some reactions you did not predict. Individuals and systems can adapt to an intervention in ways nobody designing it anticipated, and that is not a sign something went wrong. It is simply what adaptive systems do.
The next time an old rule or target seems to be losing its bite, it might not be a coincidence. It might just mean the system has finally learned it.
What does adaptation look like in your work? Tell us in the comments!
Related reading: Feedback Loop: What It Actually Means · How Do We Know Our Work Is Actually Working: Theory of Change

