TO THE EDITOR:
Dr. Mackowiak [1] proposes that the "preservation of the species rather than survival of the individual [is] the essence of evolution." This concept is logically untenable. Evolution results in the formation of new species and in the extinction of others. If species are preserved, no evolution occurs.
Richard Dawkins' book The Selfish Gene [2] is a cogent polemic against "the erroneous assumption that the important thing in evolution is the good of the species (or the group) rather than the good of the individual (or the gene)."
Dr. Mackowiak advances the hypothesis that "the febrile response and its mediators might have evolved both as a mechanism for accelerating the recovery of infected individuals with ... mild to moderately severe systemic infections and for hastening the demise of hopelessly infected individuals, who pose a threat of epidemic disease to the species." However, he then undermines his hypothesis by identifying fever as adaptive in such contagious epidemic (or endemic) diseases as poliovirus, Coxsackie B virus, rabies, and herpesvirus but as maladaptive in gram-negative bacteremia, which is never epidemic.
If fever is adaptive for most individuals, then individual selection will maintain this trait in the population, and no need exists to invoke group selection as an explanation for the persistence of this trait. If fever is maladaptive for most individuals, can group selection explain the widespread phenomenon of febrile response to infection? This is unlikely, given that group selection is an extraordinarily rare evolutionary phenomenon that occurs in special circumstances that do not seem present here [3].
It would be more fruitful to view the maladaptive aspects of fever in the host as side effects of the pathogen's struggle to maximize its own reproductive fitness. Some symptoms of disease (for example, diarrhea in cholera and phlegm production in respiratory infection) are clearly maladaptive for the host but favor the pathogen's transmission to other hosts, thereby enhancing the pathogen's reproductive fitness [4].
1. Mackowiak PA. Fever: blessing or curse? A unifying hypothesis. Ann Intern Med. 1994; 120:1037-40.
2. Dawkins R. The Selfish Gene. New York: Oxford University Press; 1976:2.
3. Johnson RB. The group selection of variola minor in the Americas: an anthroponootic analogue of the myxomatosis epizootic in Australia. Med Hypoth. 1986; 19:341-4.
4. Johnson RB. Human disease and the evolution of pathogen virulence. J Theor Biol. 1986; 122:19-24.
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