On to what, if one could be said to have favorites in this context, the theorist who would have to be mine, Jean Piaget, and our cognitive development. The first stage of cognitive development is called the sensorimotor stage, and is characterized by the engagement in the physical world. This stage is concerned with the development of two primary milestones: object permanence and language acquisition. Object permanence is the ability to conceive that an object, or person, continues to exist even when it is out of sight. This initial feat of memory is the beginning of our mental gymnastics across time. The second, language acquisition, is not strictly speaking the full access of language, so much as the beginning to express themselves in symbols. This is the very first step in abstract thought, the ability to turn a concept into a symbol.
At this point I think that we have enough on the table to begin talking about the developmental process. We have mentioned stages and aspects and phases, and maybe it still feels like we haven't described anything, yet. We know that people are complicated, so it stands to reason that the developmental process, if it is to be in any way accurate, will be at least similarly complex. Generally, the way that complex problems are broken down is by isolating different aspects and dealing with them in isolation before then considering them in collaboration. Which is actually exactly what psychology has been doing for the last couple of decades! Great news. So, applying our First Law of Human Dynamics, we want to identify different parts of people that we think every person has.
First we can identify the body. We all have one. At least, as far as I am aware. When I run into a disembodied human I will update my perspectives. So we have a body, and that body goes through a series of changes that compound in a gradual process leading to a greater complexity, and an accompanying greater range of functionality. This is the foundation for a lot of the changes that happen in the other areas of development. To be clear, I am not suggesting that every psychological change is entirely determined by biological changes. There are definitely social, cultural, geographic, and general environmental factors that come into play. What I am saying is that some of these developmental changes are made possible by biological changes. The ability to walk depends on the post-natal growth of the inner ear allowing for balance. Puberty follows the advent of hormones and a bump in brain space. There are things that we can do that hasten or inhibit those biological changes, but those biological changes create new capabilities and functionalities. If I want to understand the process, I start with the biological, and then I understand different aspects in light of those biological parameters.
This is a good point to address what has been a frequent misunderstanding in the many conversations that lead to this project. DNA is awesome. We understand a lot about the mechanics of how we work in light of the recent work in genetics. I just submitted my 23andMe sample a few weeks ago. I'm excited to know about my genetic marker and predispositions, because I know exactly what they are: markers and predispositions. Here is the critical distinction: genes are not fate. A high-risk allele just indicates that your risk is higher. You then have a choice as to whether or not to modify your behavior to adjust for your higher risk. What appears to be the difference between genes and fate is human volition. We have a lot of influence acting upon us at all times, and usually by being aware of them we can more appropriately decide how to respond to them.