Victim of Biology and Circumstance?

An area of controversy in the life sciences relates to the relative roles of genetics and the environment. Confusion commonly afflicts politics. For example, early Communists glommed on to the discredited genetic theory of “inheritance of acquired characteristics.” This theory holds that changing a person’s attitude and behavior would somehow result in changes to his or her genes, which would allow for genetic transmission of the changed attitudes and behavior to his or her children. For this idea to be true, outside influences on the brain would have to change the genes not only in brains but also in the sex cells (sperm and egg cells). The idea was held in ancient times by Hippocrates and Aristotle, but it gained scholarly imprimatur with formal publication in 1809 by Jean-Baptiste Lamarck. In the 1930s, the Russian president of the Soviet Academy of Agricultural Sciences, Trofim Lysenko, applied the doctrine to Soviet agriculture with disastrous results. At the same time, Soviet political leaders extended the mistaken doctrine to inheritance of educational and social experiences; that is, changing human nature by government policy. They expected that indoctrinating the current generation in collectivism would genetically transfer collectivist attitudes and behavior to all future generations. Cuba, North Korea, and China showed that collectivism can be transferred culturally but not biologically.

In the United States, much political angst arises from disputes over whether more effective educational and social policies will succeed in lifting people out of poverty and dysfunctional behaviors. When I was a child, I often heard the axiom, “You can take the boy out of the country, but you can’t take the country out of the boy.” Today, the corresponding axiom would seem to be, “You can take the boy out of the ghetto, but you can’t take the ghetto out of the boy.” The reality is that you can take the country or ghetto out of the boy, but this won’t transfer to his children by his genes.

What we are now discovering is that environment and experience affect the expression of genes. Whether or not genes are accessible for readout often depends on the environment. People have underestimated their capacity to sculpt their own brains, attitudes, and behavior by controlling experiences that affect gene expression. Though people may control to some extent how their own genes are expressed, there won’t be any biological transfer to their heirs. Environmental and cultural influences do of course transfer, so one’s heirs can be taught how to likewise exert control over how their genes are expressed.

Having the right chemicals in the right environment at the right time is believed by most scientists to be all that is needed for creating life and shaping the mental life of the individual. To them, life seems like a highly improbable occurrence. But it did happen, and even more improbable, there may be a life force that sustains it.

Many scientists also think of the brain’s conscious mind as an emergent property of brain function. Emergent properties follow the rule that the whole is greater than the sum of its parts. Another way of saying this is that the properties of the whole cannot be predicted from what you know about the properties of the contributing parts. Yet, paradoxically, most scientists believe that as they learn more and more about less and less, they will somehow explain the whole.

Emergent properties apply both to molecules in a primordial soup that generate simple living organisms and to the 87 billion or so neurons of a human brain that generate a conscious mind. A physical world that can generate emergent properties is a mysterious and magical world indeed.

What gets left out in such consideration is the capacity for personal control over one’s biology, which is an important theme. I contend that at the level of the individual person, mind itself—especially conscious mind—is a major force of natural selection that drives creation of mental capacity and character. The implications for daily living could not be more profound. Accepting one’s biology and circumstance breeds helplessness and fatalism. So, it boils down to one’s belief system. Either you are “captain of your own ship, master of your own fate,” or you are shackled by the belief that change is not possible. What you think and do shapes your brain's function.

Excerpted from Mental Biology. The New Science of How the Brain and Mind Relate, by W. R. Klemm. New York: Prometheus. See rave reviews at WRKlemm.com, click on "author."

Brave New World of Gene Change in Brain

In recent years scientists have discovered mobile pieces of genetic material that move around inside cells. These pieces are called retrotransposons. They can copy themselves and insert near and into DNA and thus induce mutations. Australian research recently reported in the journal Nature reveals that retrotransposons can alter the genome of human brain cells. In fact, retrotransposons more effectively penetrate neuron genes than those in blood cells that were used for comparison. Thousands of retrotransposon mutations were seen in two of the five areas examined from brains of human post-mortem donors.

Though these pieces of DNA are not genes, they interact with genes that hop around to different sites within a chromosome (perhaps you heard about Barbara McClintok’s 1983 Nobel Prize winning discovery of “jumping genes”). All cells have enzymes that cut transposons out of a string of DNA, which then insert back in at other locations in the DNA. Sometimes the cut includes an adjacent gene along with the transposon, and thus when reinsertion occurs the gene hitchhikes along to the new location. The jumping around is not random; it occurs preferentially into active protein-coding regions, even sometimes in a different chromosome. The potential for changing function is enormous, yet we don’t know just what functional consequences occur. We do know that the process is most common in humans and higher primates.

We have known for some time that all cells are influenced by epigenetic effects; that is, events in the environment can alter the genome. The mechanism may well involve retrotransposons. Gene manipulation may be especially robust for altering learning and memory. It may be no accident that retrotransposon mutations were seen in human hippocampus, the brain region most directly involved in forming memories and the one part of the brain where new cells are continuously born in adults. Memory of learned events results from more or less lasting changes in the junctions (synapses) among cells in the circuits that processed the learning. These lasting changes are enabled by new protein production in those synapses. That protein is under genetic control (thus a memory can be sustained because the genes can replace any protein that degrades over time). 

Aldous Huxley, 1894-1963

The implications of this discovery for learning and memory―and brain function in general―are inestimable. More importantly, and here is where the “Brave New World” comes in, there should be the potential for manipulating gene functions in predictable and lasting ways by using synthetic transposons (which should be easy to manufacture).  Transport of synthetic retrotransposons into neurons might be accomplished by packaging them with a harmless virus; the basics of “transfection” technology are already well established. The hard part will be in discovering what transposons produce desired changes in brain function. But it seems reasonable to test various retrotransposons in the hope that some can be found that will help to cement or magnify memories and perhaps others that erase unwanted memories, as occur in post-traumatic stress syndrome. There is a potential down-side, however. Some retrotransposons may be a cause of cancer.

Source:

Baillie, J. K., et al. (2011) Somatic retrotransposition alters the genetic  landscape of the human brain. Nature. 479: 534-537.

NOTE: My new book on practical ways to improve memory will be released on August 1. You can order now at http://www.skyhorsepublishing.com/book/?GCOI=60239100060310