Evolution does not have an aim but we could leverage it for a specific use. This is the theme of two articles I found recently (humm…say not long ago). The first is a new article in PLOS Computational Biology (Spanish source and PLoS CB paper) . The theme of the paper is that evolution does not tune the mutation rate for the long term. As one of the authors mentions (translated from Spanish in the press release): One of the most interesting problems in evolutionary biology is that of trait optimisation. That is, natural selection does not have a long term vision and acts only short term. As a consequence, traits that are beneficial in the short term but which could affect negatively its evolutionary future could fixate in the organism.
The idea would then be that you can change the evolutionary path of a species by favouring traits that in the long term would be detrimental.
One blog entry pointing in that direction is that of Olivia Judson’s in the New York Times (NYT). Dengue is a virus spread by mosquitoes and for which there is not known vaccine and that is on the rise. Judson describes a method that could be used to interrupt the transmission of the virus by genetically engineering the mosquitos that spread it. The idea is to put a gene that would kill mosquitos in the pupal stage. The next step would be to release male mosquitoes with that mutation into the wild and let them mate with female mosquitos. The twist is that the killing gene would be activated only in the presence of certain food. So if this male mosquito is, otherwise, fitter than the wild version and manages to spread the killing gene in the entire population (and, although not stated, I imagine that this is crucial, otherwise there could be a come back of the orginal population), then you would only need to add the special food in order to vanish the disease carrying-mosquitoes. A similar therapy but applied to cancer has been suggested by Wistar’s Carlo Maley (look for sucker’s gambit in his site).
The mosquito idea sounds too wacky – I can’t see it working. You would need several generations for the allele frequency to get high enough. You would also have to be sure that the deleterious gene and whatever genes made the males fitter couldn’t be split by recombination. And you would also have to be sure that the mosquito couldn’t re-colonize.
There was quite a bit of theoretical interest in these ideas a few years ago – they call it “evolutionary suicide”.
It’s ironic, really, that there are all these red-listed species that we are unintentionally killing off, but it’s so difficult to kill off some of the ones we don’t like.
Bob, I hope you realise the idea of evolutionary suicide went extinct shortly after invasion.
Well, there you go. You turn your back for 5 years, and the next thing you know, a theory is red-listed as Extinct in the Wild.
For more on harnessing evolution to stop disease, here’s an interesting TED talk on the subject