July 1, 2012
To be posted on Silentnursery.com and Nobabies.net
Professor Patrick Bateson
ppgb@cam.ac.uk
http://www.zoo.cam.ac.uk/zoostaff/bateson.htm
Dear Professor:
This is an unsolicited shameless, plug for Plasticity, Robustness, Development and Evolution Patrick Bateson and Peter Gluckman Cambridge University Press, Cambridge 2011. I intend to post it on my web site. Since you wrote the book you know what’s in it and I invite you to take a most cursory glance at this, but I thought simple courtesy dictated I let you know what I am saying about it. If you would like to respond either to me or to the site I of course would be delighted.
I read this book because I liked Mate Choice so much and because I found the contents important and central to my work. I fully expected this one to be peripheral to my own interests. It gets right to the heart in two ways.
The general theme of the book is that the distinction in animals between nature and nurture, between genetic effect and environmental effect has become so simplistic as to be misleading. When I saw that this was where the book was headed I thought, “Heredity and environment. They seem petty clear to me. How does he expect to make this stick?” Well you do make it stick, and my brain is much the better for the exercise, I’m sure.
You point out that nature and nurture cannot be opposites because one is a state and the other is a process. You point out that while the genomome encodes information used in developing the body there are ambiguities, whereby the same genome can produce different body types according to environmental clues and there are redundancies such as the case where the HOX gene cluster that functions as the source of the information that lays out the basic body plant can be removed and yet the body develops just the same, there being other ways to accomplish the same function. On top of that there are feedback loops between the genome and the environment and between environmental cues and choices made by the animal. And all of these things are going on at every level of organization. The result of all of this, not just the genome, is what is exposed to evolution.
This touches my interest in kinship and fertility, what you term “optimal outbreeding.” Optimal outbreeding is conceptually different in humans and animal. With farm animals it means optimizing fertility while maintaining desirable characteristics. For me with humans it means optimizing stability of a population.
I have long been troubled by an observation. I frequently hear, “There are too many babies in the world,” which is quite true in my mind and which is rendered worse by the fact that they seem to go to the places least prepared to nurture them. When I hear it I think, “That is your opinion. And indeed your own lack of children is consistent with it.” But reviewing the graph of number of grandchildren against shared ancestors on page 65 of your book there is little room for opinion to be effective. Shared ancestors predict the number of grandchildren within very tight limits. What scraps of relevant data I can find suggest that the process is epigenetic, and I am trying to work out the underlying chemistry as well as how it works to produce the effect.
So the question is, is it opinion or is it chemistry? Is it nature or nurture? There is plenty of evidence for opinion affecting fertility: birth control most obviously. Yet the sum of those opinions yields an effect that is quite predictable. Now I feel reassured. There is no answer because it is not a good question. What is going on is no doubt more complex than I or anybody else could ever understand.
A second point of contact again involves the page 65 graph from the Iceland study. I had always been a bit unsure of the ordinate “Mean of standardized number of grandchildren.” I had taken the zero line to be “population does not grow or sink.” But I was unhappy with that. But I thought that before I troubled you for a clarification I would make a more concerted effort to find out. I finally ran across the same statistical method being used [Average Number of Children per Woman Butler County Ohio 1930, Warren S. Thompson, Director of the Scripps Foundation, published in Washington 1941 and printed by Edwards Brothers Incorporated, Lithoprinters, Ann Arbor, Michigan 1941 Downloaded June 27, 2012 from http://books.google.com/books?id=FDDIAAAAMAAJ&pg=PA16&lpg=PA16&dq=standardized+number+of+children&source=bl&ots=ba9GVFDUfd&sig=u12PMI7BAASNf-HfknACN1DiDqQ&hl=en&sa=X&ei=gsXrT_3aMImc9gS1nfXBBQ&sqi=2&ved=0CEsQ6AEwAA#] and saw that they simply averaged the number across the whole range and then calculated whether each point on the graph lay above or below that level and by what proportion. So zero does not mean, “break even.” Zero means “same as the average for Iceland as a whole.
At first blush, then, there does not appear to be a very strong effect. If total strangers marry the result is only 5% below average. But if kin at the optimal outbreeding (for farm animal) level of consanguinity marry the effect is 20% above average for a total of 25% loss of fertility because of the choice. There is also a graph for children, which is very similar except at quite low levels of outbreeding. So the affect accumulates over generations, for two generations for sure and I believe for more as they went back ten generations to calculate kinship, and one would expect them to have up to a 50% fall in fertility over a couple of generations.
As fate would have it, the crude birth rate in Iceland fell from 3.4 births per woman in 1968 [http://www.tradingeconomics.com/iceland/fertility-rate-total-births-per-woman-wb-data.html] to 2.14 children per woman, the highest in Europe [http://www.expatica.com/de/news/european_news/Iceland-tops-European-birth-rate-chart-_50817.html] last year. That’s 38% in 45 years, or not that far off 50% in two thirty year generations. Of course that’s a “might be” not a “must be.” You can find all sorts of things if you look at enough statistics. I do not find sources to be particularly consistent.
So my thought that the zero line meant no growth must have been true on at least one day during the past ten years.
So thank you for a splendid read and for a profound insight into biology.
Sincerely,
Linton Herbert
I am delighted to report that Professor Bateson responded a second time. However he did not mention giving me permission to post his remarks and besides there are some styistic contrasts between his book and the letter and I am not totally convinced he wrote the letter without the input of an assistant.
There have been 59,449 visitors so far.