Note: I just started to listen, and this is only on the new radio station near Nelson.

Woot! I personally love hubby’s cousins who live in the small towns of BC’s interior! They had the best stories at a recent family gathering.

Especially about the Sons of Freedom sect of the Doukhobors.

As a professional in the fields of genetics, genomics, and evolutionary biology, I generally try to give a great deal of slack to non-professionals who are attempting to discuss these topics in a constructive way. That being said, I must take exception to two things David Shenk said in his interview (NB, I have not read his book). First, his descriptions of heritability studies, especially in twins, was inaccurate and not representative. The negative connotations giving to probability, statistics, and the use of the term heritability are unwarranted (this is technical term that has issues when used with non-professionals), suggesting his misunderstanding more than anything. Second, his conclusion appears to be that everything is so dependent on everything else that we cannot know anything. The inability for science to be usefully predictive now does not mean their are fundamental barriers to that understanding that cannot be overcome in the future.

He implied that “geneticists” have signed off on his writing implies that his statements represent scientific consensus, which is not accurate. Shenk, in the interview, seems to conflate public confusion over genetics with scientific controversy.

My apologies for the long comment.

Thanks for the great comments, Josh and Jim. There’s a lot to say in response. First, let me say to both of you that if either one of you want a review copy of the book, I’d be happy to arrange it — just go to my blog and email me from there.

First to Josh’s comments about heritability. If you interpreted me as merely trying to denigrate statistics and probability, then I wasn’t doing a very good job of articulating my point. I wasn’t trying to put down statistics, but to point out that statistical distinctions are not always going to reflect biological truths. I’m sure you are aware of the critique of the interpretation of heritability studies coming from Patrick Bateson, Jablonka & Lamb (pp. 363, 364), and others. Your point that “heritability” is a technical term that is misused by non-professionals is also a huge part of the point I’m trying to make. Because it sounds so much like “inherited,” journalists (and some scientists) have often taken the wrong meaning from it. Part of my criticism here is that the word should not have been used in the first place by scientists because it is so destined for popular misunderstanding and abuse. I do have a lot more to say about heritability in the book — let me know if you want to take a look and discuss.

Your second point is not as clear to me. As you state it, that’s certainly not what I believe.

To your third point, about geneticists and others signing off on my work, let me say this. First, yes, I am extremely proud that my work has been carefully vetted by very smart scientists and endorsed by some very reputable ones as well — Rudy Tanzi at Harvard, the great Patrick Bateson , Mark Blumberg at Iowa. I do acknowledge early on in the book that I am not speaking for all scientists, and that there is some disagreement on some issues — though, I suspect if you read my book you’ll see that very little of the scientific work falls outside the realm of consensus. I think you’re right that I am guilty of occasionally slipping into a conflation of public confusion and scientific controversy, and I’ll try to be more careful about this; the truth is that there are a lot of moving parts to the book (and the overall argument) and since most of them are much more about public confusion, that’s where I tend to go rhetorically in a public discussion.

Those are my replies to Josh.

***

Jim,

I appreciate your question: “From the perspective of an adult individual, what difference does it make whether they have a capacity fixed by genetics or fixed by early environment (either in the womb or in the first few years of life)?”

In my view it makes a huge difference. First, just explaining the difference is an important part of educating people who have a rigid, outdated understanding of how genes work. Second, while it surely is true that every adult reading my book or following this conversation is already well past the point of absolute pitch being fixed in one direction or another in his/her particular brain, there are future generations to contend with. Perfect pitch and other musical abilities are great examples of how parents and the culture around them may influence the development of children.

Incidentally, it’s a mistake to refer to height and night vision synonymously. Height is a developmental trait — strongly influenced by genes to be sure, but also influenced by all sorts of other things, some of which are in our control if we care to learn about them more. We don’t happen to be very aware of it right now, but we do have an impact on our height with decisions we make as parents and with priorities we choose in our culture. I discuss this a little in the book and there’s a terrific article about it in the New Yorker by Burkhard Bilger (2004). I don’t want to leave the impression here that I particularly think we should try to manipulate our height, or that it could ever be completely in our control. But the broader point is that the more we learn about development, including very early development, the more we are going to be able to impact it in small ways and some large ones. So, yes, the distinction between fixed-by-genes and fixed-early-on matters now, and will matter more and more as time goes on.

best,

David Shenk

David,

Thank you for your reply. Hopefully, I was clear that, having not read your book, that some of my critiques were based solely on the podcast version of your interview, which is a constrained format. Therefore, the second half of my original comment was on the impression given, not on assumptions of your true position. Given, however, that your critique of scientists is in part on the impression they give the public, I claim turn about as fair play, as it seems you recognize.

Heritability is a difficult concept. First, part of my critique is based on the use of language placing the blame for confusion on the scientists. While not absolving them, the use of technical terminology when communicating with the public is a problem in many fields. Science journalists have also failed us by either not asking for an explanation of terms or not stating the explanation when provided. As a counter-example, DJ Grothe on the podcast “For Good Reason” (and formerly of “Point of Inquiry”) generally does an excellent job of insisting on the definition of technical terms in his interviews.

The utility of “heritability” studies varies greatly. Bateson’s critiques are interesting and often appropriate, but one must bear in mind that his primary field of study is ethology (i.e., animal behavior, in European). Behavior is an extremely difficult field for genetic study, as behavior, which can be very hard to quantify objectively, is necessarily a response to environmental stimulus, which can be very difficult to control experimentally. As experimental control and the ability to rigorously define the phenotype decline, so does the utility of the associated statistical measures.

You are, justifiably, concerned with what I would call GENE BY ENVIRONMENT INTERACTIONS, in which the effect of a gene variant depends on the environment. ON one hand, I’m concerned that you are portraying the genetics as being hypersensitive to the environment to such a degree that we have no predictive power. On the other hand, heritability is best understood if one defines the environmental conditions for which that measure is valid. When research says, “trait X is Y heritable, when we control for Z conditions”, that is actually saying that those Z conditions may be important in the trait for any given individual.

At one time, I made a stab at demystifying some of the confusion that surrounds heritability, which you may read here: http://www.scientificblogging.com/rugbyologist/blog/heritability_primer

As you will see, I’m actually sympathetic to your position that heritability is misapplied in many cases, especially in regard to humans, but I fear we approach a baby and bath water situation.