In this episode we first walk through two broad classes of viewpoints: the prescriptive vs the descriptive. Prescriptive views dictate how life should be, whereas descriptive views are concerned with understanding how life actually is.
We then introduce the descriptive framework of evolutionary thinking: how to think about the world in an evolutionary way. It rests on four pillars.
Pillar 1: Evolution is historical and contingent
An evolutionary mindset understands that actuality determines potentiality. What something is, determines what it can become. Adaptations are more of a pirate ship than a space shuttle. Evolution works in intermediate steps, and each step must be favored by natural selection.
Our bodies are the result of billions of small incremental steps which have optimized genetic transmission to the next generation, but these optimization are constrained from what they have been scaffolded on top off. We discuss the example of the blind spot in the vertebrate eye (“the scotoma”) to showcase that evolution is historically contingent. The vertebrate eye is limited by the orientation of light sensitive patches of its distant ancestor. The scotoma does not exist because it is adaptive, but rather because of a dependence on history.
Pillar 2: Evolution is functional
An evolutionary mindset cleaves nature based on function. We conceptually organize the body into component parts (heart, lung, liver) based on what their purpose is. For example, we divide the heart from the lung because the heart pumps blood throughout the body, while lung is responsible for gas exchange. We separate them because they each perform distinct functions.
Evolutionary thinking understands the body is adaptive, it is a collection of these adaptations, each responsible for solving recurrent problems of survival or reproduction. This functional mindset allows for discerning the proximate vs ultimate causes. The proximate deals with “how” whereas the ultimate deals with “why.”
Distinguishing the proximate vs ultimate cause is the only way to allow for informed decisions. Without understanding the purpose of a mechanism we can not know the effects of its removal or modification. To illustrate this, we go over the example of morning sickness.
Pillar 3: Evolution is a blind process
An evolutionary mindset recognizes that evolution has no “conscious goal”, rather, it is a blind directionless process. It is a process which describes how heritable traits change in a population over time. Those things which survive and spread are those things which maximize their genetic transmission to the next generation.
Evolution therefore, does not necessarily reward “happiness”, or “well-being.” These emotions exist only insofar as they maximize an organism’s ability to survive and reproduce. Happiness is not an end unto itself, only a means to an end.
Pillar 4: Evolution has trade-offs and constraints
An evolutionary mindset recognizes that adaptations come with trade-offs and constraints. They “work-on-average” rather than “perfectly” under all circumstances. We discuss the example of the peacock’s tail. The tail is not fully optimized for intersexual selection because it is constrained by the selection pressure of predation.
“Perfect” solutions rarely, if ever exist. There are a host of problems an organism must contend with over its life, and solving one inevitably comes at the cost of solving another. The result is that all adaptations are mediated by the respective weights of problems present in the environment. The heavier the problem, the more that selection will favor organism’s with adaptations that solve it at the expense of other problems.
