The "Ewwww factor"

Genetically engineered rise that incorporates human genes is provoking an "ewww" reaction from some people.

Scientists have begun putting genes from human beings into food crops in a dramatic extension of genetic modification. The move, which is causing disgust and revulsion among critics, is bound to strengthen accusations that GM technology is creating "Frankenstein foods" and drive the controversy surrounding it to new heights. <snip> Environmentalists say that no one will want to eat the partially human-derived food because it will smack of cannibalism.

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OK, I can understand that, but...

What does it mean to insert "a human gene" into another organism?

It means a gene that happened to be one of the 30,000 (or whatever the number is these days) in the human genome.

There are a lot of genes in our genome that appear, in a slightly modified form, in other species. Some genes appear in a few groups of organisms, and others are found in all living things.

A gene that codes for histone proteins, for example, will be found in one form or another in every animal, and probably in most plants as well. Because these genes are strongly conserved, there'll be very little difference between one of our histone genes and, say, the same gene in a squirrel. If we find (just to make up a number) that 2% of the DNA bases differ between our histone gene and a squirrel's histone gene, what happens if we insert that gene into the wheat genome? We're inserting a squirrel gene into wheat. If 98% of that gene is identical to the human analog, have we inserted 98% of a human gene into wheat? If we eat that wheat, are we being 98% cannibalistic?

If we eat fish, we're eating a creature whose histone gene might have 94% of its DNA bases in common with human histone genes. Does that mean we're being 94% cannibalistic? If we replaced that gene with a human one (for whatever reason), does that 6% change in one gene out of tens of thousands make that much of a difference?

It's hard to see how that little bit of difference is all that significant.

So why put a human gene into rice in the first place?

The gene makes an enzyme, code-named CPY2B6, which is particularly good at breaking down harmful chemicals in the body. Present GM crops are modified with genes from bacteria to make them tolerate herbicides, so that they are not harmed when fields are sprayed to kill weeds. But most of them are only able to deal with a single herbicide, which means that it has to be used over and over again, allowing weeds to build up resistance to it. But the researchers at the National Institute of Agrobiological Sciences in Tsukuba, north of Tokyo, have found that adding the human touch gave the rice immunity to 13 different herbicides. This would mean that weeds could be kept down by constantly changing the chemicals used. Supporting scientists say that the gene could also help to beat pollution. Professor Richard Meilan of Purdue University in Indiana, who has worked with a similar gene from rabbits, says that plants modified with it could "clean up toxins" from contaminated land. They might even destroy them so effectively that crops grown on the polluted soil could be fit to eat.

Interesting. I hear complaints about plants that are modified to resist herbicides. "Are they planning to make people more resistant to the pesticides in our food?" People imagine this resistance will result food crops being loaded with chemicals. Farmers will take advantage of this resistance to load crops with high levels of chemical, because they can.

But it turns out it doesn't work that way.

Since the resistance is conferred using genes that speed the breakdown of the pesticide, we don't need to become more resistant. The food crops break down the chemical into harmless compounds, and the weeds can't do it before they die from its effects. By the time the food crop is harvested, all the chemicals that were applied are long gone, broken down by the plants and disposed of.

And in case people object to the possibility of eating plants that were used to break down toxic waste? Plants absorb carbon dioxide and turn it into glucose, and ultimately, into more plant. Carbon dioxide is a waste product excreted by animals. If you don't think it's a toxic waste, try breathing air containing even very small amounts of the stuff. We rely on the ability of plants to break down this toxic waste and turn it into food.