The Systems of Systems and Systems Thinking
"A system is a set of things—people, cells, molecules, or whatever—interconnected in such a way that they produce their own pattern of behavior over time." - Donella Meadows.
The use of Dichlorodiphenyltrichloroethane (DDT) in malaria control has been controversial for decades. Environmental harm caused by DDT is debated against the health benefits of its use in malaria prevention.
Unattended Consequences
During the early 1950s, a severe malaria disease broke out among the Dayaks on Borneo, an island in southeast Asia. The World Health Organization (WHO) was called in to assist. They came up with what they thought was a good idea for eliminating the disease. The idea was that if they could kill the mosquitoes carrying the disease, the problem would be solved. DDT was their weapon of choice. Spraying took place inside dwellings, which in each village were longhouses, large thatched-roof buildings that could house up to 100 families. The chemicals caused mosquitoes to die and malaria to decline. The mission was accomplished. However, other insects were also affected. As with all complex systems, such as an ecological system, there were other unanticipated consequences. The first was the roofs falling on the villager's heads. In addition to killing mosquitoes, DDT also killed wasps. Caterpillars are eaten by wasps. Before DDT, wasps controlled the caterpillar population. As the caterpillar population grew by about 50%, they destroyed the villagers' thatched roofs (grass hut roofs). Since there were no wasps, the caterpillars multiplied and thrived, gnawing their way through the roofs of the villagers to the point of collapse.
Wait, it gets better. Other insects were also affected by DDT. Insects are eaten by geckos. Geckoes do not metabolize DDT very quickly, and they retain the chemical for a long time. Over time, the geckos accumulated relatively high levels of DDT. However, cats do not have the same metabolism as geckos, and as nature would have it, cats eat geckos. As a result, cats start dying. Once the cats began to die, rats grew in number, and two new diseases were spread by rats, sylvatic plague and typhus. The Dayaks have traded malaria for sylvatic plague, the same bacterium that causes bubonic and pneumonic plague in humans. They are also facing food shortages. It turns out the rats run amok without the cats. Rat overpopulation caused not only the plague but also the destruction of grain stores.
At this point, the Dayak people call the World Health Organization again, but it is not malaria that is a problem. But this time, WHO didn't have a ready-made solution and had to devise one. They parachuted live cats into Borneo. The Royal Air Force conducted Operation "Cat Drop" to stabilize the situation. WHO collected new cats from coastal towns, placed them in parachute-borne containers bulging with cats of every age and rage, and helped the Royal Air Force (RAF) drop them. There are many stories about these cats with parachutes attached to diaper-like harnesses around their bodies.
Systems Thinking
"Mission accomplished" is an excellent example of an anti-pattern to Systems Thinking. Over time, a single change in a system will produce patterns of behavior. There will never be a point when you can say the mission is accomplished. Systems are constantly changing. You must continuously re-learn and adapt the system as you desire to change it.
