Category: Articles

Longer pieces; we’d call them essays if that didn’t sound pretentious.

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Scary climate change story

ResearchBlogging.orgA paper ((Lobell, D.B., Burke, M.B., Tebaldi, C., Mastrandrea, M.D., Falcon, W.P., Naylor, R.L. (2008). Prioritizing Climate Change Adaptation Needs for Food Security in 2030. Science, 319, 607-610.)) and commentary ((Brown, M.E., Funk, C.C. (2008). Food Security Under Climate Change. Science, 319, 580-581.)) in the latest Science make pretty compelling reading for anyone with an interest in how climate change will affect agriculture and food security. Long-standing readers will remember a little round-up that included the work of our chums Andy Jarvis and Annie Lane. They predicted the effect of climate change on the suitability of different areas for different crops. David Lobell and his colleagues at Stanford University take a different tack, to answer a slightly different question: what are the top priorities for investing in agriculture to cope with climate change.

They isolated 12 regions where most of the world’s malnourished people are concentrated. Then they analyzed 20 different climate change models to get a feel for how temperature and rainfall would change in those areas. And finally, they looked at the specific crops that people in those regions eat and used past correlations between yield and temperature and yield and rainfall to predict how those crops might respond to the predicted changes in climate. This is an important step. As the researchers point out, “Rice, maize and wheat contribute roughly half of the calories currently consumed by the world’s poor and only 31% of the calories consumed by those in sub-Saharan Africa”. There’s a whole bunch more jiggery-pokery in there that ends up allowing the researchers to come up with best and worst case scenarios for each of the regions they consider, and some sharp conclusions.

Southern Africa and South Asia are going to be hit hard. Maize in Southern Africa and wheat and millet in South Asia are likely to show large declines. But there are also regions with large uncertainty, with some models predicting an increase and others a decrease. Groundnut in South Asia and sorghum in Southern Africa are examples of these, probably because the historical data on yield correlations are poor.

The results are summed up in a table that, the authors point out, could help agencies decide where to invest scarce resources. Those that are really risk averse might focus on wheat in South Asia, rice in Southeast Asia and maize in Southern Africa, all of which are predicted to drop by all the models. An investment in those crops is most likely to generate “some benefits”. A different view would be that investment should focus on crops and regions where at least some of the models predict strong depression of yields, because even if the projection is unlikely, if it does happen the consequences will be great. Many crops in South Asia, along with sorghum in the Sahel and maize in Southern Africa fall into this group.

The bigger question is, what form should those investments take? This is where the commentary adds its 2 cents worth. Molly Brown and Christopher Funk point out a double-whammy awaiting poor farmers:

In food-insecure regions, many farmers both consume their product and sell it in local markets. This exposes farmers to climate variations, because when they produce less their income goes down while their costs go up to maintain basic consumption. Large-scale hunger can ensue, even when there is sufficient food in the market that has been imported from elsewhere.

The solution that Brown and Funk see is largely technological; irrigation, fertilizers, improved varieties. Indeed, they aver that “technological sophistication determines a farm’s productivity far more than its climatic and agricultural endowments,” and of course at one level they are right. They also say that “poor farmers in the tropics will be less able to cope with changes in climate because they have far fewer options in their agricultural systems to begin with”.

I wonder whether that is correct. For the most marginal farmers, without irrigation or fertilizers or improved varieties, options — in the form of agricultural biodiversity — is all they do have. Development agencies are again starting to pay attention to agricultural research, and the Lobell paper and others on climate change are going to help them focus their efforts. It is clear that all approaches will need to be explored, among them helping people to adopt new foods in their diets and cultures. Will that include helping the most marginal farmers to use agrobiodiversity — local and exotic — to secure their food supplies in the face of climate change?

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Golden rice redux

OK. Mea culpa. Jorge Mayer, Manager of the Golden Rice project, rightly took me to task for using out-of-date data about the carotene content of the new generation of Golden Rice. The project’s web site says:

The recommended daily allowance (RDA) of vitamin A for 1-3 year-old children is 300 µg (half the RDA is enough to maintain vitamin A at a normal, healthy level). Based on a retinol equivalency ratio for Beta-carotene of 12:1, half the RDA would be provided in 72 g of the new-generation Golden Rice. This is perfectly compatible with rice consumption levels in target countries, which lie at 100-200 g of rice per child per day.

I confess, I did not find that, as it wasn’t actually my primary concern. My primary concern was to ask whether the approach Golden Rice embodies, its mindset, if you will, is actually going to deliver the goods as effectively as some other approaches. Is it, for example, what vitamin A deficient people would choose for themselves?

The Golden Rice project’s home page says that:

The best way to avoid micronutrient deficiencies is by way of a varied diet, rich in vegetables, fruits and animal products.

The second best approach, especially for those who cannot afford a varied diet, is by way of nutrient-dense staple crops.

It then goes on to explain how some cereals, such as rice, are capable of producing provitamin A in the leaves but not in the grain, because some of the necessary genes are switched off in the grain, and how the inventors of Golden Rice inserted those genes from other species “to account for the turned-off genes”.

So far so good. And maybe that’s as far as things need to go. But here is where I part company from the project.

In the most remote rural areas Golden Rice could constitute a major contribution towards sustainable vitamin A delivery mechanisms. To achieve this goal a strong, concerted, and interdisciplinary effort is needed. This effort must include scientists, breeders, farmers, regulators, policy-makers and extensionists. The latter will play a central role in educating farmers and consumers as to their options. While the most desirable option woud be a varied and sufficient diet, this goal is not always achievable, at least not in the short term. The reasons are manifold, ranging from tradition to geographical and economical limitations. Golden Rice is a step in the right direction in that it does not create new dependencies or displace traditional cuisine.

And right below that paragraph is a crosshead that reads:

Golden Rice will reach those who need it at no additional cost

Note that “consumers” are passive recipients of education. I really do not see the chain that binds Golden Rice to “the most remote rural areas” “at no additional cost”. How are those people going to get their Golden Rice? As a handout, in perpetuity? As a supply of seeds? Furthermore, and this was my original point, if a varied and sufficient diet is the most desirable option, is there not a danger that the inherent sexiness of Golden Rice and the scientific attraction of cutting-edge genetic engineering could possibly be creating a funding well that draws in support to the detriment of that most desirable option? Why, indeed, is that most desirable option not always achievable?

Golden Rice, as a poster child for engineered biofortification, has come a long way. Those promoting it have become much less strident and have sought to build alliances. But I haven’t seen anyone willing to give the most desirable option — a varied and sufficient diet — a fair crack of the whip.

That was my point. I’m happy to concede that Golden Rice could deliver provitamin A. I’m just still not sure it is the best way to do so.

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Time for a test?

A few things have come together at the same time in that serendipitous way that makes me value even more the pattern detecting abilities of dear old Homo sapiens. First, I blog a feature that takes quite a close look at what the Gates Foundation is trying to do with (for?) agriculture in sub-Saharan Africa. Then I read a post from Marcelino over at Biopolitical arguing that the best way to help the poor may be to give them money. And finally, Karl over at The Inoculated Mind, introducing our post on high-carotene maize, says this: “Grrr, the opposition to humanitarian efforts such as golden rice sure gets my blood boiling … perfect for this weather”.

And I think, hmmmn, I feel a hypothesis creeping up on me.

Let’s go back first to Marcelino. He quotes Robin Hanson, an economist, who says:

A suspiciously large fraction of people who claim to care about the third world poor believe that the best way to help is to pursue their favorite hobby or career, and not to just give the poor money. Medical researchers seek disease cures, computer folk build laptops or subversive software, musicians hold concerts to inspire donations, policy wonks lobby governments to build schools, and so on.

That certainly seems true of the Golden Rice effort. The reasons it is unlikely to help the third world poor are many. Even the new improved version does not contain very much in the way of vitamin A precursors; you would have to eat an awful lot of it each day — probably an amount impossible to ingest in a day — to overcome the levels of malnutrition seen among the poorest children. The people who need it most are not going to be able to afford it — indeed, they are often out of the cash economy completely. And as for giving them seed and expecting them to grow it, their effort would probably be much more successful ploughed into more diversity in their fields and in their diets. Dark green leafy veg and orange fruits could make a much greater contribution than golden rice.

So the idea that Golden Rice was created, or given away, to help the third world poor does seem a little far-fetched. At the very least, the idea wasn’t thought through very carefully.

Then there’s the Gates Foundation’s support for agricultural research, which to me on the outside often seems to be suspiciously like using the previous generation’s weapons to fight the generation before that’s battles. Now, Gates wants results, and he wants impact. So, why not let two (or more) methods fight head to head?

Take two villages, or even two countries. Give one a bunch of cash to spend with scientists and others solving problems in a genuinely participatory way, trying some weird stuff (like agricultural biodiversity) along the way. For the other, put the usual advice to work in the usual ways. Give them both, say, five years. Then see which has improved most.

Simplistic, I know, but what, actually, is wrong with the idea? Smart people (not just me) are criticizing current approaches with sensible suggestions. Humour them, listen to them, do the experiment; then one way or another we’ll know. And smart people, as opposed to those who merely have an axe to grind, will change their opinion based on the results.

Something like this could have been tried with the Millennium Villages, but as far as I know it hasn’t. I wonder what would happen if you created the equivalent of a voucher system for research and development, and gave poor people in rural areas a choice of how to use their vouchers.

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More to maize evolution than selection

Our thanks to Hannes Dempewolf for this guest post.

ResearchBlogging.org What forces drive maize evolution and what factors contribute to the generation of maize agrobiodiversity? This question has been the focus of a recent study, published in PNAS. ((Dyer, G.A., Taylor, J.E. (2008). A crop population perspective on maize seed systems in Mexico. Proceedings of the National Academy of Sciences, 105(2), 470-475. DOI: 10.1073/pnas.0706321105))

Contrary to the popular opinion that maize diversity at present is largely a result of artificial selection on local germplasm, the authors call for careful consideration of the ‘larger social context of maize evolution’ and explore the implications of ‘farmer-led selection’ on maize diversity. Using a theoretical approach, underpinned with some empirical data, they investigate the interplay between farmer-led selection and informal seed systems. This can result in the spread of varieties that are not necessarily ones of superior agronomic properties, but are favoured due to other factors, such as superior seed supply mechanisms:

…A frequent supplier of seed might be a farmer whose seed is faithful to a type. His seed line will be well represented locally or even fixed… Another farmer that keeps a stock of maize might be known as a sure supplier of seed when others are lacking. His seed might not be preferable to others’ but might still become locally predominant if the seed population is small. If the population is large, the demographic outcome depends not only on the rate at which he gives out seed but also on how long he keeps it.

In the context of their discussion of seed replacement, they correctly recognize that

High revenue is of less concern to subsistence farmers, who deal with a larger set of issues and overwhelmingly prefer landraces…New seed does not always perform well, especially nonlocal types acquired through informal seed systems. Farmers test seed and discard ill-adapted and inferior types. Most introduced seed is replaced after its first year, more than twice the rate of local seed.

However, introduced germplasm which has not been discarded might introgress into local seed stocks and help to maintain diversity: “When more variation within a locality is lost than created, an external source is required to maintain diversity… It is unlikely that introduced seed is displacing local types systematically.” This is because most introduced seed is not kept true to type but hybridizes with local landraces. What the prevalence of hybridization means for the genetic makeup of local landrace varieties is still unclear, but this question has received considerable attention lately, especially in the context of GMO risk assessments. ((Soleri D, Cleveland DA, & Aragón Cuevas F (2006) Transgenic crops and crop varietal diversity: The case of maize in Mexico. BioScience. 56:503–514.))

The view that, once markets are well developed, farmers shift to adopting improved varieties and hence cease to maintain diversity seems not to hold true in the case of maize in Mexico. There doesn’t seem a loss of diversity even in well developed markets. Diversity at the local level might instead be the result of individual farmer’s unintended actions, as described above.

Further contemplating the role of farmers in maize evolution, the authors suggest:

Farmers’ main goal is appropriating value, whether economic, cultural, or ritual. Whereas some might achieve this through improvement of local seed stocks, others might prefer to keep these stocks unchanged, defying our conceptions of improvement. Others may find it optimal to replace those stocks. It does not follow that seed improvement and conservation traditionally have been performed by farmers specialized as seed curators. Unlike modern maize farmers and breeders who specialize in distinct tasks, most Mexican farmers engage in seed improvement, diffusion, and farming simultaneously. Although individual management decisions have a specific intent (i.e., to preserve or replace seed), it is the sum of farmers’ actions that drives changes in maize populations. These actions can have unintentional albeit predictable effects on the metapopulation dynamics of maize.

One limitation of their study, as the authors acknowledge, is their assessment of the system at one single point in time. They suggest that even after major disruptions of the seed systems, such as catastrophic weather events, normal dynamics are bound to return after seed diffusion through government and relief agencies has ceased. Although these dynamics might indeed return, it would be interesting to see how the genetic makeup of the maize genepool changes in response to human intervention on such dramatic scales.

Social aspects of crop evolution, although undeniably of great importance, have received only limited attention by many students of evolutionary theory. One can only hope that papers like this spark the debate and contribute to a more rigorous scientific exploration of these complex interactions between social factors and crop population genetics.

It should be interesting to see how demographic modelling attempts on the evolution of crops other than maize are taking into account these factors. One could well imagine that this might lead to a major change in the way crop evolution is understood by many researchers.

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Can’t stomach golden rice? Get your teeth into golden maize!

ResearchBlogging.orgVitamin A deficiency causes eye disease in 40 million children each year and places another 200 million or thereabouts at risk for other health problems. In sub-Saharan Africa and Latin America, between 17% and 30% of children under the age of 5 suffer vitamin A deficiency. Simple solution: give them more vitamin A. But how?

The poorest regions, which stand to benefit most, often do not have the infrastructure to deliver vitamin supplements, either directly or in fortified foods. Diversifying the diet is dismissed out of hand. ((Full disclosure: I don’t myself buy the reasons given for not doing more to diversify diet, but this is not the place for that argument. This is: Johns, T. & Eyzaguirre, P. B. (2007). Biofortification, biodiversity and diet: A search for complementary applications against poverty and malnutrition. Food Policy, 32(1), 1-24.)) So the technical types turn to plant breeding, and in particular the notion of biofortified foods, whereby staple crops are selected to contain higher levels of micronutrients. It was this approach that gave the world Golden Rice, by shifting one of the enzymes in the carotenoid synthesis pathway from daffodil to rice.

An ungrateful world still has not accepted golden rice as the saviour of blind little children, but the technical types have not stopped working. In the latest Science ((Harjes, C.E., Rocheford, T.R., Bai, L., Brutnell, T.P., Kandianis, C.B., Sowinski, S.G., Stapleton, A.E., Vallabhaneni, R., Williams, M., Wurtzel, E.T., Yan, J., Buckler, E.S. (2008). Natural Genetic Variation in Lycopene Epsilon Cyclase Tapped for Maize Biofortification. Science, 319(5861), 330-333. DOI: 10.1126/science.1150255)) a large team led by Edward Buckler at Cornell University, reports on a different approach to biofortification.
Harjes2Hr

So what other staples are there, preferably ones that might already contain the genes to make vitamin A precursors? Step forward maize, some varieties of which have yellow and even golden orange kernels. It is not enough, however, simply to look at the maize kernels and score them on some scale from pale yellow to deep orange. The reason is that not all carotenoids are created equal. Beta carotene is the precursor of choice, because it contains two of the necessary chemical rings to make vitamin A. Shade of yellow correlates very poorly with total beta-carotene. But all this is detail above and beyond the call of duty. The point is that maize varieties display enormous variability both in total carotenes and in the proportion of beta carotene.

Maize varieties are also hugely genetically diverse. In fact, the differences between two maize varieties is considerably greater than the difference between humans and chimpanzees. Buckler’s group took the known variability in maize kernel colour and asked whether genetic differences were associated with the carotene profile of the variety. They were. The gene for one particular enzyme — lycopene epsilon cyclase — has a large effect on the provitamin A carotenoids.

There’s more in the full paper (which requires a subscription), but one reason that this could be an important result is that it is reasonably easy for others to make use of it. Genetic markers for the favourable versions of the crucial gene make it possible for breeders to look for the potential in any varieties they have that are already adapted to the conditions for which they are breeding. The favourable type is reasonably widespread, so finding parents for crosses should be reasonably easy. Analyzing carotenoid compounds is expensive and difficult, but scoring the target gene is not only about 1000 times cheaper, it is also well within the capabilities of those developing countries that need more vitamin A.

The contrast with Golden Rice couldn’t be greater. That is a proprietary technology that has graciously been made available to those who have the expertise to make use of it. This approach to a nutritionally-improved maize should be much simpler to put to work. Information needed for the DNA analysis is being made freely available, as are inbred maize lines that could make it easier for breeders worldwide. So things look good for biofortified maize, at least technically.

There’s just one remaining little problem — will people eat yellow maize, even if they know it is good for them? Changing human feeding behaviour can be so much harder than changing the food they eat.

Stop press: Prefer wheat to maize or rice? Golden wheat comes a step closer too, with a paper in Euphytica. Italian and Spanish wheat breeders transferred nuclei from wheat into cells from wild barley and from wild wheat relatives. Wheat wild relatives increased the amount of lutein, another carotenoid.