Category: Domestication

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Rusty conclusions about iron deficiency

Iron deficiency anaemia is a big problem. WHO estimates that about 2 billion people — that’s roughly one in three — lack enough iron in the diet. And the consequences are grave for health and the economies of developing countries. So of course people are focused on ways to combat iron deficiency. Two hog the limelight: supplementation by adding iron to the diet and biofortification, breeding to add more iron to the staples that make up the diet. A recent paper in The Lancet reviews the story of iron deficiency and how to treat it. ((Michael B Zimmermann and Richard F Hurrell, Nutritional iron deficiency, The Lancet, 370 (9586), 11 August 2007-17 August 2007, Pp 511-520.)) Perhaps not surprisingly, the study concludes that “targeted iron supplementation, iron fortification of foods, or both, can control iron deficiency in populations”. And yet, having said that “dietary iron bioavailability is low in populations consuming monotonous plant-based diets,” the authors do not appear to have seriously considered the idea of trying to attack that monotony instead. Maybe enriching and diversifying those plant-based diets to include more dark green leafy vegetables and more pulses would be as effective, with additional benefits in other realms. But that kind of intervention isn’t nearly as glamorous, and gets little attention.

Of course, it could be that solving the problem of iron deficiency will just give rise to other difficulties. Another paper suggests that iron deficiency protects us against some of the epidemic contagious diseases that have hitched along as people crowded together in agriculturally-fed cities. ((S Denic and M Agarwal, Nutritional iron deficiency: an evolutionary perspective. Nutrition. 2007, 23:603-14. Epub 2007 Jun 20.)) Maybe iron deficiency — at least in moderation — is a good thing?

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A second helping of rice

More today to satisfy your hunger for rice information, hot on the heels of the recent paper trying to explain the pattern of genetic variation across and within two subspecies of cultivated rice, discussed by Jeremy a couple of days ago.

First there’s a paper ((Global Dissemination of a Single Mutation Conferring White Pericarp in Rice. Sweeney MT, Thomson MJ, Cho YG, Park YJ, Williamson SH, et al. PLoS Genetics Vol. 3, No. 8.)) looking at how the red pericarp of wild rice became the white pericarp of cultivated rice. The answer is that a mutation arose in the japonica subspecies, crossed to the indica and became fixed in both under very strong selection pressure by ancient rice farmers. They must have really liked those funny mutant white grains when they first noticed them! Oh to have been a fly on the wall — or a brown plant hopper on the rice stalk — when the white pericarp mutation was first noticed in some ancient paddy…

Then comes news that the three CGIAR centres with an interest in rice — IRRI, WARDA and CIAT — are to boost their collaboration to solve the pressing production problems of Africa. There’s talk of forming a consortium. More flags being prepared.

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Diversity in rice varieties: what caused it?

Larry Moran has a very good article on the genetic diversity found in the DNA of rice varieties. I won’t try to summarize what he has to say, because he says it so well. But I will emphasize something that he doesn’t. The biologists who looked at rice wanted to know what caused the pattern of diversity they see across rice vareties. One possibility is selection. The other is the founder effect, where a very small subset of a larger population gives rise to a new species (or variety) so that the new species contains less diversity than the ancestor population from which it sprang. In rice, neither explanation on its own is sufficient.

An agricultural scientist might not care one bit, or might simply assume that it was all due to selection by farmers. But the truth is that it needed a combination of the founder effect and positive selection to create modern rice diversity. The founder effect relates to the fact that Oryza sativa indica and Oryza sativa japonica were both domesticated independently from the wild Oryza rufipogon, maybe a few times. The results of those early events set up the foundation genes for rice. Then selection was brought to bear and created the diversity we now see. Luck and hard work, every time.

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Farming butterflies conserves forests

East African farmers are making good money — and conserving their local surroundings — by going after butterflies. The Manila Times picks up a story from Agence France Presse reporting from the villages in Kenya and Tanzania where locals have learned how to trade in butterflies. The article is built on the words of the farmers themselves, and it makes for uplifting reading. A sample:

“I would be foolish to cut trees,” says Suleiman Kachuma, a 42-year-old villager, who earns between 15 and 23 dollars a month from his work with Kipepeo, double what he used to make selling timber.
“Before, people had a few chickens and goats… Now there is a big change. Farmers have more chickens, some even have some cattle. The project really changed our lives,” he says.

I thought I’d seen this somewhere before, and I had.