Like nature, the human body must maintain a fragile balance in order to thrive. The smallest factor can effect human ecology. Human ecology can be thought of in two ways. There is human ecology in the sense that humans effect their environment and vice verse. However, their is also a fragile ecology inside the human body. This type of human ecology can be thought of as biology ecology. While humans can effect their natural environment the same cant always be said for our effect on our biology ecology. In some sense humans have control over their biology ecology. However, our environment and heredity can also directly effect the fragile balance in our bodies.
Getting lung cancer is an example that could be explained in either way. Human ecology might say that a person got lung cancer because they were a heavy smoker throughout their lifetime or where exposed to known cancer causing material such as asbestos. These days, people are aware of the effects of smoking on the human body and should act accordingly. By smoking or exposing ourselves to known carcinogens, we as the subject, caused ourselves to get lung cancer. However, lung cancer can also be explained through biology ecology. Certainly if the subject smoked and introduced a foreign substance into the human body, they caused the effect on the biology ecology of that subject. However, it could also be said that that persons biology effected the outcome of cancer. There are people that never smoke or purposefully exposed themselves to known carcinogens and they still get lung cancer. Those people may have not had a balance in their biology ecology and could complete no outside action (human ecology) to directly effect the outcome of lung cancer. We cannot always be held responsible for our biology or how it effects us. Regardless of the type of ecology, balance is always a necessity for an organism to thrive.
Human ecology may study the social reason for our smoking habit. It may also study the reason that society has allowed known carcinogens such as lead, to remain in our environment. In studying the social interaction between humans and their environment, human ecologists are able to find solutions to problems that are caused as a direct result of interaction between humans and their environment. Biology ecology may study biological factors in the human body that are out of our control. By studying the relationship between humans and their bodies, ecologists can sometimes find links in other types of ecology and find ways to produce a positive outcome.
Human health depends on many ecological factors. In many cases, humans have the ability to effect those factors. Humans can usually change their environmental factors through geography or through direct environmental contact. While we can not always change our biology, we can change environmental factors that will effect our biology. Humans have the ability to change many factors that effect us both directly and indirectly.