July 5, 2012
to be posted on nobabies.net
Anthony D. Barnosky
Department of Integrative Biology
University of California
Berkeley California 94720
I had read your article, or rather that of your team, in the June 7 issue of NATURE, and seeing that it at least grazed my own field of interest had prepared to mention it on my web site. Yes I remain haunted by your words and have a question that I feel constrained to pass on.
I understand how terribly busy you are and how fan mail is a nuisance to a celebrity like you save that it validates your celebrated status. There was a movie “Enemy at the Gates,” the title referring I think to a quote of Cicero, about the siege of Stalingrad. I saw only a bit of the movie, but at one point a sniper remarks more or less that colonels care little for telephone operators. I am hoping on this point that I, as he, shall be proven wrong.
I trust I do acceptably little violence to your paper to say that there is evidence that biological systems tend to fluctuate around a mean in terms of any parameter you might select. Such a system can be destroyed in one fell swoop or may be nudged imperceptibly past some tipping point, after which its destruction is also assured. The warnings of such a threshold are subtle and may consist of fluctuations that are more frequent, more pronounced and show an asymmetrical time course.
My own interest is in medium term demographic shifts. On this point I have become such a bore that I have achieved almost complete social isolation. The bottom line is that we always married cousins in the old days and had lots of children and now never marry cousins and have so few children that unchecked this must wipe us out. Here is a link if you want evidence that this is a causal relationship http://nobabies.net/Orlando%20meeting.html but there is little point in following it up. You know perfectly well it’s true. Everybody does.
Sometimes when the weather is pleasant and other worries are few I turn to Gapminder.org and have the computer run up a graph with number of children per woman on the horizontal axis (the top choice on the menu of axes) and age at first marriage for women (under the “population” button on that menu. Then I have the computer run the graph, for every country in its data base, over the years since 1850. This never fails to restore my gloom.
During the greater part of the last century and a half, it looks to me like age at first marriage is different in different countries but almost constant within a country. Fertility fluctuates like any viable biological system would. Then, perhaps it is my feverish imagination, maybe, you’d be able to tell better than I, those fluctuations increase in frequency and size. And then, in different years in different countries, births per woman plunges, never to recover. Does that mean the tipping point is already past, that a biosphere change is underway and already irreversible? None of those countries will ever recover a sustainable birth rate, and other countries are following right along?
Then the birth rates stabilize. They stabilize below replacement but they stabilize and even increase to a degree. This has been seized by the UN as salvation. Fertility will stabilize at replacement levels. Sure it will. In medicine we once had the phrase “Spes tuberculorum,” the unreasonable hopefulness of the dying consumptive.
The test is the other coordinate. Generally age at first marriage is constant, or at least only fluctuating imperceptibly until fertility has fallen below replacement. Then, with exemplary coordination, it starts inexorably upward. Think how strange that is. Women are waiting longer before starting their families – their biological clocks are stopping – but they are still dropping the same (if inadequate) number of babies. Obviously this is not a trend that can be maintained forever. There must come a time when the age of marriage comes after fertility has finished. At all events, it looks like a second tipping point has been passed. A permanent change in the biosphere is on the way and it looks like the extinction of one of my favorite species.
But don’t worry about how it feels. How does it analyze from a mathematical standpoint?
Sincerely,
M. Linton Herbert MD
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