There are two questions that I have found are worth asking myself when undertaking any complex task. These questions are, What am I trying to do? and How am I tying to do it? In undertaking the task of writing The Physics of Living Systems, I will be trying to show how two concepts “propensity” and “selection” interact. The fact that propensity and selection are two separate processes seems to have been largely overlooked by the scientific community. People either combine the two processes or assume that either one or the other is the only process that needs to be considered. This leads to confusion about what one is measuring.
Propensity and selection are two separate variables. Propensity is an individual variable and selection is an environmental variable. The interaction between differences in propensity and differences in selection factors is what creates outcomes. When the outcome is a rate of occurrence in a population, the rate is the cumulative result occurs because many individuals with varying propensities for action interacted with many different environmental situations over the time period being measured.
The primary problem is that the variation in propensity is typically distributed normally in the population. In many cases the environmental conditions also vary normally. When two normally distributed variables interact, changes in one or the other can have highly non-linear effects on the outcome. The cumulative distribution of outcome rates is a sigmoid curve.
For example, when looking at crime rates, it is easy to confuse the crime rate with the propensity to commit a crime. For example, if the car theft rate is 12% in 2022 and 10% in 2023, there is an implicit assumption that the propensity to steal cars has gone down. It is also probable that
The answers to these questions are hard for me to formulate. There is a lot going on in my head. I have been thinking about the topics I will be covering in this book for several decades. Whenever I start to write on one topic, three or four other related ideas pop into my head. That is why I am writing four book instead of one.
The Physics of Living Systems is an online book that provides two areas of study. At the individual level, I will offer a new perspective on how living systems function. At the population level, I will show how individuals interacting with the environment create statistical patterns.
At the individual level, living systems are “complex adaptive systems.” Adaptation is occurring at two levels of analysis. Between and within individuals. It seems that between individual variation has been studied more that within individual variation.
We seem to have a good understanding of between individual variation. At the genetic and environmental level, an infinite variety of possible states are created between individuals. Therefore, some individuals in the population have a good chance of surviving when changes in the environment occur. Assuming that the environmental changes are not too drastic, and there is sufficient between individual variation, some individuals in some species should survive and reproduce. The population will change to adapt to the environment.
There seems to be less of an understanding of within individual variation. There are infinite variety of states within the individual. Living systems use “high dimensional chaos” to maintain the ability to change almost instantaneously when required. The caveman musing at the fire will get up and grab a spear in a second when the saber tooth cat appears. The processes that drive the high dimensional chaos in living systems have not received much attention. My work approaches this topic at a macro level. I will be exploring the dynamics of within individual variation and how the characteristics of individual trajectories might be studied to help us predict outcomes and produce more reliable interventions.
You can read Explorations in Science for a more autobiographical introduction to how I came to develop The Physics of Living Systems.
The initial work involved self-analysis and simple observation but, as time went on, I started doing more empirical research. This lead to several discoveries about the nature of changes in human characteristics and the related changes in population measures such as crime rates or health spending.
As my analyses continued, I realized that I had stumbled upon basic facts that apply to all living systems from the most basic to the most complex. My basic premise is that living systems operate using a universal blueprint. The blueprint for life is built upon the concept of variability. Individuals are infinitely different from each other, and also changing from moment to moment so that an individual is never the same from moment to moment.
Traditional scientific methods tend to focus on sameness. That is, a human is generally similar to other humans, a bacterium is generally similar to other bacteria, etc. My thesis is that all organisms use similar processes in different ways to create life. Genetic variation creates infinite variation between individuals within a species, and high dimensional chaos creates constant change within the individual. These two things make life possible and robust enough to allow species to survive.
In general, scientists have tried to deal with the issues related to the “why” of between and within individual variability by ignoring them. When these issues are addressed, the subject is not dealt with directly. Scientists develop “work-arounds” to deal with variability.
For example, psychometric tests deal with “inter-individual” variability (variability between subjects) under the heading of “validity.” A “valid” test will find the differences between subjects with sufficient accuracy for the test results to be useful. The fact that most tests have fairly low validity is simply a “fact of life.”
“Intra-individual” variability (variability within the subject) is dealt with under the heading of “reliability.” A reliable test should give the same result each time. The fact that tests are not reliable and give different results on repeated application is simply accepted as another “fact of life.”
My premise is that we should understand the reasons tests have low validity and are unreliable, rather than ignoring the problem. We should understand the “facts of life.”