Malaria has evolved cold tolerance

To put matters in perspective, consider a related problem that has stumped malaria.  Although malaria is a ferocious parasite, quite willing to eat anything that gets in its path, P. falciparum needs a warm climate to reproduce.  If the temperature falls below about 65°F, the parasite slows down.  When the temperature gets to 61°F, it can’t reproduce  It’s stymied.  If a mutant parasite appeared that was tolerant to somewhat lower temperatures–not to freezing conditions, just to cool temperatures–it would be able to invade regions that are now closed to it.  Edge of Evolution, 82

Behe seems to think that P. falciparum is the only malarial parasite that infects humans.  P. falciparum is restricted to quite warm regions, but P. vivax has indeed invaded much cooler regions, including London in past centuries.  P. vivax tolerates temperatures of five degrees Celsius cooler, which amounts to nine degrees Fahrenheit cooler:

Compared with the more virulent Plasmodium falciparum, P. vivax tolerates a wide range of temperature environments (minimum: 16°C vs. 21°C for P. falciparum), which may explain its broader distribution. Host Switch Leads to Emergence of Plasmodium vivax Malaria in Humans

Then too, since Behe has no idea of what temperatures P. falciparum endured in the past, he does not know that it has not evolved to tolerate lower temperatures than it could initially.  Regardless of that, it is unsurprising that a Plasmodium species can live in cooler regions than can P. falciparum.

And when one species can survive in a region in which a related species cannot, competition often prevents evolution to fit the competitor’s adaptation.  After all, it may require several changes to endure cooler temperatures, and they may initially come with costs which make the species less fit.  When one species already can endure cooler temperatures it is not particularly likely that another species will, and especially not in the rather short time period in which P. falciparum has been infecting humans.  Nevertheless, P. vivax suggests that it could happen in other species, particularly if somehow P. vivax went extinct.

Behe could always ask why P. vivax can’t endure 6°C, or -6°C, or cryogenic temperatures.  And who knows, maybe he will.   But as I have previously argued, it is not for us who accept the constraints of science and evolution to explain why evolution is not all-powerful, it is for him to try to explain why his omnipotent god fails to reveal omnipotence in “his designs.” 

Evolving to live at lower temperatures has not “stumped malaria,” as he claims.  In fact, with P. vivax living at lower temperatures, P. falciparum‘s lack of evolution to tolerate lower temperatures is in line with evolutionary expectations, considering the relatively short time in which it has has to evolve.  So there you are, malaria seems to fit evolutionary expectations quite well, and Behe fails in this detail as well.

This is part of a series of posts that I am combining into one long post, which may be found at The Edge of Evolution

Explore posts in the same categories: The Edge of Evolution

One Comment on “Malaria has evolved cold tolerance”

  1. monado Says:

    Malaria plagued the people of Ottawa when the Rideau Canal was being built.

    This link has some of the history of malaria in Ontario, which gets below freezing in winter. One thing that it mentions is that P. vivax can suspend its life cycle and go dormant in the liver, surviving to re-infect mosquitoes in spring.

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