Genetic Diversity and the Green Revolution

One of the common criticisms environmentalists make of the Green Revolution is that it supposedly reduced the genetic diversity of crops. Usually environmentalists complain that by doing so, the world’s crops are open to being wiped out by a single catastrophic crop disease. This scenario is certainly scary, but is it true?

Melinda Smale of the International Maize and Wheat Improvement Center set out to examine the status of genetic diversity in wheat. Her paper on the subject, “The Green Revolution and Wheat Diversity: Some Unfounded Assumptions,” maintains there is insufficient evidence for claims that the Green Revolution caused either genetic erosion of wheat crops or an increase in genetic vulnerability to disease.

First, Smale notes that much of the environmentalist concern is highly exaggerated even if their worst fears were accurate. As she notes, there doesn’t at the moment seem to be any shortage of potential genetic wheat combinations,

Given the size of the wheat genome and possibilities of incorporating genes from wild relatives or unrelated species through biotechnology and other breeding techniques, genetic combinations do not seem determinate in number.

There also doesn’t seem to be much risk of genetic vulnerability to disease in and of itself leading to catastrophic crop failure. The classic case of such a scenario is the destruction of 15% of the U.S. corn crop in 1970 due to disease, but as Smale notes that was hardly catastrophic. The real weakness to catastrophic crop failure is not so much genetic vulnerability but a lack of infrastructure in some countries to deal quickly and efficiently with outbreaks.

That said, when it comes to bread wheat the act of domestication itself appears to have significantly decreased genetic diversity. Smale writes,

According to some scientists, the utilization of bread wheat landraces maintained in collections offers only limited possibilities for diversification within the gene pool constituted after domestication … Continued farmer selection and modern plant breeding have extended wheat cultivation into new and different area, creating diversity in one sense and narrowing it in another. Statements about the relative breadth of the genetic base of wheat over time seem more a matter of scientific intuition than of scientifically proven fact.

In other words, what those who claim a lack of genetic diversity fail to realize is that agriculture by its very nature involves a selection process which reduces genetic diversity.

Which explains when it comes to the supposed increased in vulnerability to disease, Green Revolution varieties seem no more prone to disease and may in fact be more resistant thanks to the process whereby hybrids such as dwarf wheat were chosen than traditional varieties. Smale writes,

Data from screening nurseries for advanced breeding lines used in the developing world also show a gradual increase in the level of resistance to rust since the late 1960s.

Smale’s paper certainly does not rule out the possibility of declining genetic diversity in wheat and other crops, but it does mean that those who make the claim must step up to the plate with more concrete numbers and analysis beyond the vague claims and predictions that have so far been presented.

The full text of Smale’s article appears in World Development, Vol. 25, No. 8, pp. 1257-1269, 1997.

Werner Fornos’ anti-immigration efforts

Werner Fornos, with the Population Institute, made his way through Michigan on a speaking tour a few weeks ago, but my child was sick that day and I missed his lecture when he was in town. I did get a friend to tape it for me, though, so expect to see a critique of Fornos’ particular message of doom and gloom added to the Overpopulation FAQ soon.

In the mean time, the Detroit News, one of Michigan’s two major dailies for which I occasionally do freelance work for, did send a reporter to cover Fornos when he spoke in Detroit and wrote an excellent editorial entitled Apocalypse Deferred pointing out the errors in Fornos’ anti-immigrant fearmongering. Check it out.

The Overpopulation FAQ joins the ‘brownlash’

Reading a recent newsletter at the Zero Population Growth web site, I realized this site is solidly part of the “brownlash.” For those unaware, “brownlash” is the term used by Paul and Anne Ehrlich to describe “a body of anti-science — a twisting of the findings of empirical science — to bolster a predetermined worldview and to support a political agenda.”

I know, I know — it sounds like a description of Ehrlich’s books, but Peter H. Kostmayer, Executive Director of ZPG, thinks Ehrlich has a point and as an example of the “brownlash” cites Michael Sanera and Jane Shaw’s book Facts Not Fear: A Parents Guide to Teaching Children about the Environment. For those like me who haven’t read Sanera and Shaw’s book, Kostmayer describes the chapter on population “particularly distressing” and provides the following quote from page 67 of the book as an example:

With this background, you can readily answer questions that your children may ask about food and population. For example:

Are there too many people? No. The Earth’s ‘carrying capacity’ is enormous. Human ingenuity is more than equal to the challenge of meeting the demands of a growing population.

Does population growth cause starvation? No. Food production has increased faster than world population, and this trend is likely to continue.

Is the claim that “food production has increased faster than world population” a distortion of scientific truth for political gain? In their book The World Food Outlook Donald O. Mitchell, Merlinda D. Ingco and Ronald C. Duncan provide the following chart illustrating the growth of world cereals production and population based on data from the United Nations and the United States Department of Agriculture.

World cereals consumption and population growth, 1960 to 1990 (per cent increases)




Industrial economies
Total cereals consumption








Developing economies

Total cereals consumption








Mitchell, et al, along with numerous other experts on world agriculture argue world food production will continue to outpace population growth and food prices will continue to fall.

So somebody remind me — who here is twisting science to further political agendas?

What Will Replace Oil?

In the eyes of the environmentalists the fossil fuel economy is enemy number one. But what are they going to replace fossil fuels with for generating energy? According to a recent Cato Institute report, at the moment every proposed alternative energy source has both economic and environmental drawbacks which have yet to be overcome.

The best part of Robert L. Bradley’s Renewable Energy: Not Cheap, Not “Green” is the saga of wind power. Once heralded as cheap and supremely clean (what could be more clean than using wind?), the technology turns out to have unexpected drawbacks that are drawing criticism from environmentalists.

Aside from the large amounts of noise they generate and the relatively high cost of energy generated, windmills turn out to be extraordinarily effective killers of birds. As Bradley writes, “Wind blades have killed thousands of birds in the United States and abroad in the last decade, including endangered species, which is a federal offense subject to criminal prosecution.” Shades of the Exxon Valdez!

Both the Sierra Club and National Audobon Society have complained about the bird killing effects of windmills and the National Audobon Society has called for a moratorium on new wind farms unless and until the problem can be solved.

Hydropower, once considered a viable alternative to fossil fuels, has also been shelved because of environmentalists concerns about the effect of dam projects on the environment. Solar energy is still extremely inefficient and generates enormous heavy metal waste products.

Looks like we’re stuck with fossil fuels unless you’re prepared for pre-industrial nirvana.

Food: we can make it better, more abundant and cheaper?

A recently published book claims much of the environmentalist rhetoric about running out of food is fundamentally flawed. The World Food Outlook is the product of two economists with the World Bank, Donald O. Mitchell and Merlinda D. Ingco, and Ronald C. Duncan of the National Centre for Development Studies at the Australian National University.

The book jackets summarizes the main points of the book this way:

The fact is that the world food situation has improved dramatically for most of the world’s consumers. Output of cereals, the world’s main food source, has increased 2.7 per cent per annum since 1950, while population has grown by about 1.9 per cent per annum. Cereal yields have increased at 2.25 per cent per annum. Not all people in the world today have adequate diets and there is no doubting the desperate circumstances of some peoples, but diets for most of the world’s consumers have improved dramatically and per capita calorie consumption in developing countries has increased by some 27 per cent since the 1960s. It should continue to improve, and food will be cheaper than it is today.

The trio also estimate that to feed future population, agricultural growth needs to achieve at least 1.4 percent annual growth (current growth is about 1.7 percent), and a growth rate of 2 percent annually would allow up to 11 percent of the world’s crop land to be returned to other uses while still maintaining adequate food security.

More On Malaria

The Atlantic Monthly ran an enormous article in its August 1997 issue on the continued prevalence of Malaria worldwide. As author Ellen Ruppel Shell notes, almost 40 percent of the world’s population live in an area where malaria is endemic.

Shell chronicles how the World Health Organization set out to eradicate malaria in the 1950s only to see incidence rise to even higher levels by the 1960s when the eradication program was abandoned and replaced with a strategy designed to merely control the spread of malaria.

Today malaria kills close to 3 million people each year. Shell is to be credited for giving space to experts on malaria who note the often irrational fear over DDT (as opposed to rational concern about the excessive spraying of the pesticide) has removed an important method of reducing malaria deaths, although pesticide use remains a short term solution. For the long term Shell cites several nations which managed to dramatically reduce malaria deaths through extremely creative management of species which kill mosquitos.

Someday maybe malaria will be taken as seriously as a public health threat as AIDS, which kills less than half that claimed by malaria.