From Material Science to Physiology

When we observe tensile strengths of copper or glass and we do this with a hundred samples, we can get the average tensile strength of the material. We may observe how temperature and other factors influence the result. Our certainty that we have described what is happening is pretty high. And our ability to predict in the future is high.

When we boil water under a vacuum, we can chart the pressures and boiling temperatures (lower pressures = lower boiling temperature). We can change the salinity of the water and notice changes. We can reach high certainty and develop high confidence in predictions.

When we water a plant, we can observe it may grow more quickly at first and then die from over-watering later. We can try to measure many features of the plant and get a model for optimum water level for the plant. This model may change when new temperatures, new breeds, new soils, new fertilizers, etc., are included. Our model is weaker since we can’t control all the variables and may have to adjust the model with more information. Our certainty that we know exactly what is happening in all detail is moderate and our ability to predict in the future is moderate.

When we dose a human with anything, the possible variables to monitor are infinite. The possible differences between humans are infinite. And, the number of variables that we don’t know about yet to measure are infinite. Therefore, our model on how the agent and the dose works in the human is limited. This is a type of “science” that can’t make absolute claims. What works for many people, may not work for several others. Our certainty is lower than the other scenarios, and our ability to predict in the future is lower.

All of these are called science. In the first instance, we can observe the structure more closely and develop an understanding of how and why the material behaves the way it does. In the second scenario, we can observe most of the key variables. In the plant watering and more so in the human, there are limited tests we can do on the living being to see its multiple internal responses to our impact.

For example, since calcium builds bones, we might assume that eating calcium would make our bones stronger. However, the absorbability of the calcium, and the body’s choice to use or not use the calcium for bones versus other things means that eating the calcium may not always have the intended effect, especially given the presence or absence of other conditions in the body. The body has stimuli that trigger bone building, and the body may not use the calcium to build bones if those triggers haven’t been met (e.g., exercise). The body has a target range for calcium depending on many factors. It can add calcium to bones or release calcium from bones, and it’s doing both constantly. Many factors determine how the body will use the calcium. So, the science of how to get the calcium into the bones is in on-going development. Biphosphonate therapy, for example, gets more calcium into the bones but in a weaker structure. We can’t observe every gland, muscle, organ, and bone and their living responses to calcium. So, our models are necessarily limited.

All of this is called science and assumed equally to have high veracity. However, lumping them together is sometimes confusing. Since material science is far more understood than biological and more so physiological sciences, the surety of one doesn’t flow to the other. Often, medical science relies on heavily on statistical probabilities. This simply means that the expectation will apply most of the time. We haven’t always minutely observed and understood the processes; instead, we may have correlated variables as they increased and decreased. It doesn’t mean we really understand all the relevant causes and effects.

For example, we now know that dietary fat, blood cholesterol, and atherosclerotic plaque don’t correlate as closely as we once thought. There are many more factors at play. In fact, as an ultrasound technician, I’m often surprised at how someone may have a lot of plaque in one area of their body and almost none in another area. What is the mystery factor?  Sometimes what we have are statistical probabilities of what will occur with incomplete understanding of why or how or other possible effects or other possible factors.

As we receive changing information on what is good for us and not good for us, it’s helpful to listen to our own bodies.