GM plants: when the evolutionary issues trump all others

We discussed GM technology and some of the debate about it on Friday.  Today we're addressing some other aspects of the debate that may not be as clear even to many of the disputants over the issues. These are issues that are relevant to things we often talk about here on MT.

Flavr Savr tomatoes engineered to delay ripening; Wikipedia

Why not GM?
There are numerous reasonable objections to genetic modification, some of which we touch on below.  We ignore the ill-informed reactions -- such as that tomatoes with a fish gene inserted will taste fishy, or that orange trees with a spinach gene will produce green fruit.

One objection is economic.  It is a resistance to the greedy monopoly of economic control of farming, and the exploitation of domestic and (especially) developing-world farmers.  It offends a sense of equity. 

Another source of resistance is epidemiological.  It is the distrust of the produce itself, such as that it might trigger unexpected toxic or allergic reactions. We always eat foreign proteins (we're not corn or chickens, after all), and unless we're allergic, we readily digest them, and reap their nutritional benefits.  Still there are concerns that some GMOs may engender reactions.  There have been various claims, few if any strongly as yet substantiated, for other sorts of effects (such as on fertility). 

A third is sociological, involving resistance to the displacement of more putatively sustainable multicrop, multispecies, mixed, smaller scale farms by huge monocropping.  For long-term sustainability, mixed crops save soil from runoff, require less fertilizer, fewer pesticides and are more natural.  Small, mixed farms are run by communities of local farmers, not itinerant workers, and so on. 

And, there is the evolutionary objection, which is related to the sociological objection.  The latter is in some ways the most scientifically inflammatory, or so it would seem.  It is this that is most relevant to MT and our personal interests in evolutionary genetics. The idea is that if you make a crop inedible, or make it resistant to pesticide, you put heavy selection pressure on pests, animal and plant, eventually favoring those with resistance mutations--and then you've got a real problem on your hands. Wild crops may gain transgenes through cross pollination (see Friday's post), and crop diversity, a major evolutionary asset, will be reduced. Further, as with antibiotic resistance, every herbicide or pesticide that can no longer be used is an economic jolt to farmers practicing conventional agriculture.  Evolutionary biologists opposing the Monsantoizing of the world point this out, and have done, in quite strong terms--and their warnings have been born out repeatedly.

Still....
However, this objection is not always warranted; again, not all GM is alike. Many GM changes should not have particular evolutionary implications. Transgenes that keep fruit from spoiling, or that affect its taste or color seem like examples. While such changes dramatically affect the plant or animal's reproductive fitness through the intense artificial selection that is agriculture, it's harder to envision these transgenes conferring a fitness advantage for related species if they escaped into the wild, such as is seen with pesticide or herbicide resistance.

The transgene would perhaps be more likely to have negative implications (just because it's a random gene tossed into the genomic mix of the recipient wild species). But most likely it would be selectively neutral--that is, it would have no effect on the recipient species reproductive chances.  In this case, the most likely fate of the transgene is to be lost just by chance--because this is the typical fate of any mutational change in any species.  But even if it persisted, it would have no implications for agriculture.

This seems to be the story of golden rice, with the transgenic modification to make vitamin A in rice, a potential boon to many underdeveloped countries where vitamin A deficiency is highly prevalent and rice is heavily the staple food.  A Sunday NY Times commentary discusses the issues.  The article doesn't describe the transgenic engineering that was done, but it does note that it's not a particularly strange modification, even for plants, it's developed by a non-profit institution, and the farmers can replant seeds they've grown.  So many of the ethical objections would seem to be avoided.  Still, there appear to be many reflex objections of a generic type.

Could something go awry with this plant, densely used in very widespread and global areas?  Any new gene could, in principle, interact somehow with local pests from bacteria to insects, and it is plausible in principle that some allergic or other reactions could occur.  However, this seems far less likely compared to GM species engineered in relation to strong selection involved with agents like antibiotics, pesticide and herbicide resistance.  So such objections do, at this point, seem rather a stretch, unless one is just nostalgic for some supposed good old days in agriculture.  After all, artificial selection has been tinkering with all our domesticates' genomes for millennia.  On the other hand, if someone really is pining for older ways, that's a legitimate viewpoint (even if it may ignore the real-world plight of our heavily populated globe).

Whatever one feels about GM plants, a productive debate can only happen if people actually understand the issues.  It is perfectly legitimate to object to economic, epidemiological, sociological, or evolutionary aspects of GM foods.  But many have opposite views, and are unconcerned about the industrialization aspects, for example (after all, many have jobs related to industrial ag).  In any case, it is not legitimate to mix issues.  That can't move the debate forward.

Whether GM crops are here to stay or will be displaced for either scientific or political reasons, only time will tell.  That there are very serious evolutionary issues is by now very clear indeed.  To many, they trump all the other issues.  In any case, while the epidemiological and sociopolitical sides of GM technology's impact are absolutely suitable for the policy arena, they are largely separate from the issues stemming from the evolutionary problems.

If the evolutionary issues prove to be intractable--if agribusiness can't keep one step ahead of natural selection, then we will eventually, maybe even rapidly, revert to other means of maintaining high global agricultural output.  If the problems can be addressed by big-science methods, then the overall economics--whether you like it or not--may well leave them in the driver's seat of future agriculture.  However the issues play out, billions of peoples' lives will be affected.