The Great Brain Debate: Nature or Nurture?

by John E. Dowling

How much of our behavior is determined by our genes and how much by our environment? Fiercely debated but not fully resolved, we continue to grapple with this nature-vs.-nurture question. But data from the study of the developing and adult brain are providing us with new ways of thinking about this issue ? ways that, finally, promise answers. Whether our personality, our intelligence, and our behavior are more likely to be shaped and affected by our environment or our genetic coding is not simply an idle question for today's researchers. There are tremendous consequences to understanding the crucial role that each plays. How we raise and educate our children, how we treat various mental diseases or conditions, how we care for our elderly ? these are just some of the issues that can be informed by a better and more complete understanding of brain development. John Dowling, eminent neuroscience researcher, looks at these and other important issues. The work that is being done by scientists on the connection between the brain and vision, as well as the ways in which our brains help us learn new languages, are particularly revealing. From this groundbreaking new research we are able to gain startling new insights into how the brain functions and how it can (or cannot) be molded and changed. By studying the brain across the spectrum of our lives, from infancy through adulthood and into old age, we see how the brain develops, transforms, and adjusts through the years. Looking specifically at early development and then at the opportunities for additional learning and development as we grow older, we learn more about the ways in which both nature and nurture play key roles over the course of a human lifetime.

Genres: Science, Nonfiction, Psychology, Biology, Neuroscience

198 pages, Hardcover

First published January 1, 2004

Reviews

[Mark · Rating 4 out of 5]

This book is a good primer on how the brains of humans and other creatures develop in the womb and beyond, and it deals with many of the thorny issues in the nature-nurture debate.

The bottom line for Dowling, a Harvard neuroscience professor, is that we still understand so little about the complete workings of the brain, even though our knowledge is increasing by leaps and bounds, that it is impossible to say how much of our cognitive abilities are hard-wired and how much are influenced by the environment, whether it is external signals or internal ones in the womb.

To use just one example, he notes that animal studies have shown that there is a critical developmental period where visual abilities can be altered by closing off vision to one or both eyes. In those cases, certain kinds of vision can never be recovered, and there is evidence that the other eye (if one eye has been sealed) takes over the neuronal territory of the other in the visual cortex. At the same time, though, these manipulations don't change the routing of neurons from the retina of both eyes to their first way station in the brain -- they only change the "interpretation" area in the visual cortex at the back of the brain.

If it's so hard to figure out the mix of genetics and the environment in something as straightforward as basic vision, think of the difficulties in parsing out the much more complicated areas of human memory, IQ, social abilities and other more advanced traits.

Along with other neurobiologists, I think Dowling believes that much of our brain function is inherited, maybe half or more, depending on the particular ability, but that the full interplay of genetic instructions, environmental signals, messages in utero and other factors is far from being unraveled.

He even presents his own theory for why he believes human life span will not grow much beyond the 100-120 year range: because the brain itself inevitably deteriorates and there seems to be little evidence of being able to stave off that decline indefinitely. "My own view is that our life span is determined mainly by our brain," he writes. "That neurons are not replaced in the brain for the most part and that brain structure and function gradually deteriorate with age seem unequivocal and the ultimate determinant of a finite life span ... It is possible to transplant hearts, livers and kidneys as well as other organs from humans and even animals, and artificial organs are being developed. But I don't think anyone seriously believes that we can transplant a whole brain or make an artificial brain. Indeed, even if one could do this, the uniqueness of the individual would be destroyed. Furthermore, as noted earlier, if whole brain transplantation were possible, it would be better to be the donor than the recipient!"

As you can tell from this excerpt, Dowling's writing stays firmly in the academic mode, but his knowledge of the field is impeccable and the book is a quick read.

[Essam Munir · Rating 4 out of 5]

Interesting, but it may seem boring for those with no background in neuroscience.
It slightly scratches the surface of the Nature vs Nurture debate and it's mostly about how the brain develop and what the experiments have shown.
If you're a researcher, then this book is good for you.