Sérvio Pontes Ribeiro
Um artigo recente, e arrongante, saiu na Nature, discutindo a possibilidade da erradicação dos mosquitos da face da Terra. Terrivelmente equivocado, o único consolo a ainda ver cientistas que acham que existam possibilidades de futuro em um mundo evolutivamente desconfigurado (e desfigurado em rápida velocidade, o que nos impede a chance de continuidade via seleção natural), é que o mesmo resultou em uma avalanche de críticas no site da revista. Engrossei estas críticas, e reproduzo o comentário abaixo:
"Published online 21 July 2010 | Nature 466, 432-434 (2010) | doi:10.1038/466432a
Ecology: A world without mosquitoes
Eradicating any organism would have serious consequences for ecosystems — wouldn't it? Not when it comes to mosquitoes, finds Janet Fang.
(leia na íntegra em http://www.nature.com/news/2010/100721/full/466432a.html)
William D. Hamilton died by malaria which he acquired while trying to join evidences for his final theory on evolution of sex and diseases. Since the 80â€™s until his death, his intellect was pretty devoted to demonstrate how strong is the soft-selection pressure caused by diseases and parasitism on the evolution of genetic variability, and its intriguing mechanism, the sex! More than killing people, diseases act by weakening some genotypes relatively to the others. Hence, the selection strength of a disease is directly proportional to the frequency and density of the vulnerable genotypes (what is then called soft-selection). Survival and demographic responses to a tragic epidemic event depends then on the rare resistant/tolerant host genotypes remaining in nature and kept by sexual reproduction.
Considering this scenario, it is absolutely certain that the vertebrate species have had evolved fast immunological responses to an uncountable invasive microorganisms that take daily contact with our circular system by mosquito bites. Tolerance, resistance and vulnerability are balanced accordingly to the strength of a presently acting selective pressure. As a consequence, mosquito transmitted diseases, such as malaria, dengue, etc, are likely to be an extreme minority from a huge number of microorganisms species which try to invade and colonize vertebrate bodies along the evolutionary time.
No doubt that it is just beyond naivety to believe our technology could eradicate diseases as efficiently as our body immunologic system can. The question is, are we going to be more vulnerable to diseases by having not contact with bloody-sucking organisms along the generations? Do we have how to dimension the relative importance of mosquito interactions to the evolutionary maintenance of vertebrate immunological response? One should not forget that allergy is more likely to manifest among those that grew up away from infections and dirty hands! Would we be claiming a germ-free rat life style for our future generations? Sounds horribly risky to me!
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- 2010-09-23 11:27:10 PM
- Posted by: Servio Pontes Ribeiro