The PANY Bulletin

Psychoanalytic Association of New York
Volume 39, Number 1 Spring 2001

The Human Genome
by Lawrence Kunstadt, Ph. D.

The recent almost complete sequencing of the human genome is one of the most superlative accomplishments in the history of science. What meaning does it have for psychoanalysis?

This past week (mid-February) both Science magazine in the US and Nature magazine in England published alternative versions of the genome. That there are slightly different versions of the genome stems from their being worked out by two different teams, one at Celera, a genomics company, and the other by academic scientists funded by the public purse. What has been accomplished is a first draft of the sequence of genes. As one wag put it, now the real work begins. What remains is to clarify the sequence, reconciling the discrepancies and filling in the gaps, something that will take years, and to work out what the genes actually do. This latter task is exceptionally complex. Genes are now known to produce more than one protein, to jump around on the chromosome, to be turned on and off under varying conditions of the ambient microenvironment and, perhaps most complicating of all, to interact.

Scientists believe that perhaps a third to more than half the genes have some effect on the organization and functioning of the brain. Some scientists have made claims that enormous advances will now be made in understanding psychiatric diseases for which some biological basis is suspected such as schizophrenia, drug addiction and depression, and I have no doubt that, understood properly, this is true. But it is important among all the hoopla to understand what it is that genes actually do, what they do not do and how they relate to other biological processes (I use the term 'process' for a gene deliberately).

Genes have a physical and a codical dimension. Their physical dimension refers to their physical structure, that is the actual DNA, its coiling, its sequence of base pairs, its chemistry, and so on, the "real substance" that comprise the gene. The codical dimension refers to the non-physical function of a gene, that it provides a type of instruction, a "blueprint". The gene itself is considered by many biologists to be "the transcribable information coded by the molecule", not the physical DNA (1). The distinction between physical and codical is the same as that for a book, which can be either the physical copy made of paper and ink or the content. The latter can be stored in any number of media besides paper such as CD, tape or human memory.

The codical dimension of genes is something special, not quite unique but rare, in living tissue-under appropriate conditions the code specifies the sequence of base pairs in a segment of RNA. That is all a gene does! Genes do not specify traits, as is so often claimed. They specify, and then only under certain conditions, the sequence of base pairs in RNA. This RNA, in turn, through a complex building process, specifies the sequence of amino acids in a polypeptide chain or protein. Under other conditions it may specify a different protein. What is of interest to us is that these specifications are all at the molecular level. That is, a molecule can direct the synthesis of another molecule, but it cannot directly affect a trait at a higher level of organization.
Thinking this way, there is not a gene "for" eye color, hair color or any of the many other traits undergraduates are taught are under genetic control. That is not to say genes have no effect on phenotyptic traits, of course they do, but it is not a direct specification. For a gene to affect a structure at a higher level of organization, a different type of relation must obtain.

When biologists talk about genes "for" a certain trait in an individual, they are using a shorthand phrase for a complex developmental pathway. Or, they are talking about how genes in a population affect the distribution of a trait, rather than how the trait comes into being in a given individual. For instance, if I say there is a gene for blue eyes and a gene for brown eyes, what I mean is that in a population a certain percentage of people will have blue eyes and a certain percentage brown eyes, and, assuming the trait is related to alternative genes, that this percentage varies in lawful ways from generation to generation. Used this way I am saying nothing about how the actual trait develops in an individual. This distinction is critical because the idea that a gene "causes" schizophrenia or depression or any other higher level process is a misuse, or at least a confusion, of the term "cause". Causality of DNA to RNA is one type of causality, closer to the conventional sense of linearity that is usually implied by the term . Causality from a gene to a higher level trait is something quite different and something that is not well understood.

This issue of vertical causality has become more important because one of the Human Genome Project's surprising findings is that that the human genome contains only 30-40,000 genes, not a lot more than the mustard weed's 25,000 genes. (What this will do to what is left of human narcissism after Darwin and Freud is hard to say.) This raises the importance of the question, what are the rules by which the enormous complexity of the human organism can be derived from such a relatively simple genetic system? That is, now that strict genetic determinism has been thrown out, and now that we know that there just are not a lot of genes in our human genome, how do we explain our relative complexity? Another possibility is that we may conclude that our self-labeled complexity is not an accurate description. A third possibility is that it is not the number of genes but the much larger number of proteins that matters.

Human genes "do" more than genes in other species. Each human gene, which is the same size as genes of other species, by using different combinations of coding regions, can specify the manufacturing of more than one protein. Studying this phenomenon will be one of the main areas of research over the next few years. Likewise, while humans do not have proteins that are substantially different from the proteins of other species, subunits of human proteins, called domains, are combined in novel and more complex ways than those of other species. What these findings mean is that while the building blocks of life seem to be common or at least similar throughout the animal kingdom, they interact in more complex ways in humans than in other animals. This suggests that complexity itself in the way parts of the whole interact will tell us a lot about human uniqueness. Since very few genes actually code for proteins, perhaps only 1.5%, it is likely that the key to understanding how genes affect higher level traits will come as we understand how each level "creates" the next higher level and interacts with it. That is, the question will no longer be, how does a gene determine a trait, but how do the one or more proteins coded for by a gene interact with each other to causally determine their higher level? So between the increased number of proteins and the increased degree of interaction of higher levels, we have the seeds of how our complexity may have come about.

Although we do not know the answer to this question, over the past century biologists, confronted with similar questions in evolution, ecology, development and anatomy, have started to develop a framework for answering it. The general idea is that lower levels create opportunities or potentials that can be effectuated by "selection" by a higher level. That is, once a gene specifies a protein, the proteins have the potential to interact in many different ways. How they actually interact depends on the ambient microenvironment in which they find themselves. Once they have interacted, "causing" a result in the next higher level, let's say membrane structure, the same process occurs at the next higher level and so on all the way up to the level of investigation, let's say the brain. Somehow, I believe, the answer to the mind-body problem, that is, the relation between what we call the brain and what we call the mind, lies in this general selective process.

What this means for psychoanalysis is that the mind is not a deterministic result of the genes. It is an outgrowth, although that is not a great word for what is going on, of enormously complex vertical causal processes, from genes up through cells, tissues, organs, the organism itself and its environment. Genes are only one input. So are each of the things psychoanalysts study: wishes, mother's behavior, memories, situations of satisfaction and so on. Genes are certainly no more important to understanding the individual than are his memories. I believe that the interaction of higher level processes will eventually be shown to be at least as important, if not more important, than the contribution of the genes. That is, there is no a priori reason to suspect that the rules of vertical causality do not themselves become more complex as we look at ever higher and higher level processes. Genes may turn out to be rather trivial in the whole scheme of development, just the starting blocks rather than the whole path. What will eventually reveal the uniqueness of humans are both the horizontal and vertical interactions of the enormous number of processes that comprise the organism.

"The Human Genome", Science 16 February 2001. George Williams, 1992, Natural Selection, Oxford UP, NY.