Thursday, September 25, 2003
Genetically engineering extinction
It has been reported that 50 of the 225 Marine Corps soldiers who went into Liberia have been hospitalized with Malaria. Scholars like Jeff Sachs have commented at length about the disastrous economic consequences of malaria and of living in malarial zones. After all, over a million lives are lost to malaria each year and costs African countries approx $12 billion to cope. So, I read with some interest an evolutionary biologist's insight on how it might be possible to engineer the extinction of the malarial mosquitoes.
attach a useful gene to a selfish genetic element, release individuals modified to carry the element and, within about a dozen generations, that gene should be present in every individual in a population. Or, to engineer extinction, devise an extinction gene — a selfish genetic element that has a strongly detrimental effect. The element could, for example, be designed to put itself into the middle of an essential gene and thereby render it useless, creating what geneticists call a "knockout." If the knockout is recessive (with one copy of it you're alive and well, but with two you're dead), it could spread through, and then extinguish, a species in fewer than 20 generations.
Of course, it cant be that easy, else someone would have thought of it much earlier.
As with any new technology, the benefits of using it must be measured against possible risks. Here, the risks are two: ecological collapse and genetic escape. Genetic escape is the idea that the extinction gene might somehow get into a species other than the target and inadvertently wipe it out as well. In principle, this could happen in either of two ways. Anopheles mosquitoes might not be fussy about whom they mate with; if they engage in sex with mosquitoes of other species, the gene could spread into those species and eliminate them, too.
I certainly dont have the knowledge to comment on the feasibility of the idea or whether other approaches are less risky, but an intriguing idea nevertheless.
attach a useful gene to a selfish genetic element, release individuals modified to carry the element and, within about a dozen generations, that gene should be present in every individual in a population. Or, to engineer extinction, devise an extinction gene — a selfish genetic element that has a strongly detrimental effect. The element could, for example, be designed to put itself into the middle of an essential gene and thereby render it useless, creating what geneticists call a "knockout." If the knockout is recessive (with one copy of it you're alive and well, but with two you're dead), it could spread through, and then extinguish, a species in fewer than 20 generations.
Of course, it cant be that easy, else someone would have thought of it much earlier.
As with any new technology, the benefits of using it must be measured against possible risks. Here, the risks are two: ecological collapse and genetic escape. Genetic escape is the idea that the extinction gene might somehow get into a species other than the target and inadvertently wipe it out as well. In principle, this could happen in either of two ways. Anopheles mosquitoes might not be fussy about whom they mate with; if they engage in sex with mosquitoes of other species, the gene could spread into those species and eliminate them, too.
I certainly dont have the knowledge to comment on the feasibility of the idea or whether other approaches are less risky, but an intriguing idea nevertheless.
