SPROUTING UP: HUMBLED BY THE GENOME

Sprouting Up: HUMBLED BY THE GENOME’S MYSTERIES

March 2001

These are exciting times for genomics research. At the end of January, Syngenta announced that, with Myriad Genetics, it had finished mapping the rice genome. Two weeks later, two rival teams – one from the public sector, one private – announced the completion of the human genome map. These events were accompanied my much hoopla from the agribiotech and pharmaceutical companies hoping to capitalise on the findings. According to Syngenta’s David Evans, understanding the genetic structure of rice and other cereals will "enable plant breeders to produce crops that are more nutritious, more productive and easier to process." The genome unveilings have also been applauded by public sector research institutes, such as the International Rice Research Institute (IRRI). The mapping of the rice genome will "make a very big difference to our work at IRRI, not only in areas such as biotechnology but also by greatly improving the efficiency of research," says IRRI’s Director General.

But for many people, the findings of the human genome project have raised more questions than they answer, and call into question some ground rules of science that will require a complete reassessment of the way we look at genes and how they function. One of the most profound findings was that humans contain far fewer genes than we thought. The fruit fly Drosophila possesses 13,000 – 14,000 genes and the roundworm C. elegans (which contains just 959 cells) has just over 19,000 genes. The general estimate for humans – sufficiently large to account for the vastly greater complexity of humans under conventional views – was well over 100,000. But the human genome study only came up with something in the range of 30,000. This finding has thrown out of the window the "central dogma" of genetics, which assumes that one gene codes for one protein.

Things, it seems, are a little more involved than that. It appears that the key to complexity is not more genes, but more combinations and interactions generated by fewer units of code. The implications of this finding cascade across several realms. The commercial effects will be obvious, as so much biotechnology, including the rush to patent genes, has assumed the old view that ‘fixing’ an aberrant gene would cure a specific human ailment. Similarly, in agriculture, these findings will hopefully lead to more restraint on the ‘slap-a-gene-in’ approach to crop development. The social implications are that we may finally be liberated from the simplistic and harmful idea that each aspect of our being, either physical or behavioral, may be ascribed to the action of a particular gene.

It turns out that our 30,000 genes make up only about 1% of our total genome. The rest has (rather disrespectfully) been called "junk DNA," because scientists couldn’t figure out what it was for. "We have to look beyond the genes," said Richard Gallagher of Nature, which published the findings of the public sector effort, known as the Human Genome Project. "We know what they are. We don’t know what the rest of the stuff is that is sometimes called ‘junk.’ It is that drawer you have at home that is stuffed with memorabilia. Some things are essential, like your passport and birth certificate: they are your genes. But there is other stuff that gives insight into who you are and where you came from and why you do the things that you do."

Perhaps the most interesting questions raised by the human genome map go well beyond the science of genetics. According to Harvard professor Stephen Jay Gould, "the deepest ramifications will be scientific or philosophical in the largest sense. Since the late 17th century, science has strongly privileged the reductionist mode of thought that breaks overt complexity into constituent parts and then tries to explain the totality by the properties of these parts ... The reductionist method works triumphantly for simple systems - predicting eclipses or the motion of planets, for example. But once again - and when will we ever learn? - we fell victim to hubris, as we imagined that, in discovering how to unlock some systems, we had found the key for the conquest of all natural phenomena."

Where will these new findings lead us? Gould has some answers. "The failure of reductionism doesn’t mark the failure of science, but only the replacement of an ultimately unworkable set of assumptions by more appropriate styles of explanation that study complexity at its own level and respect the influences of unique histories. Yes, the task will be much harder than reductionistic science imagined. But our 30,000 genes - in the glorious ramifications of their irreducible interactions - have made us sufficiently complex and at least potentially adequate for the task ahead."

Sources: Syngenta press release, "Researchers complete rice genome map," 1/26/01; Tim Radford, "Door opens on deeper mysteries." The Guardian, February 12, 2001; Stephen Jay Gould, "Humbled by the genome’s mysteries," The New York Times, February 19, 2001.