3 ms·

Okay so if I am understanding you correctly, your theory is this: “Diseases from animals have evolutionary pressure to hurt humans because hurting humans is be

Okay so if I am understanding you correctly, your theory is this: “Diseases from animals have evolutionary pressure to hurt humans because hurting humans is better for the survival of its preferred host.” That does make sense to me, but I think it doesn’t track with how slow evolution works. According to Yale, Lyme disease has likely been around in North America since 60,000 years ago: https://medicine.yale.edu/news-article/ancient-history-of-lyme-disease-in-north-america-revealed-with-bacterial-genomes/ https://medicine.yale.edu/news-article/ancient-history-of-ly... Natives were not very destructive to forests and I don’t think very destructive to mice. Mass deforestation to the level of evolutionary pressure would have come when Europeans first settled. Meaning Lyme disease would have had to specialize after that, which I would assume is unlikely. Maybe the diseases do specialize to harm humans, but it feels like the period where diseases can effectively stop humans and humans were doing mass deforestation is too short. Lyme disease is problematic, but it hasn’t stopped anyone from chopping down trees. You could argue it has the opposite effect. We drain swamps because of malaria, destroying its habitat.

__MatrixMan__ 3y ago
I was perhaps too zoomed in on the details of how interspecies evolutionary pressure would work. Sorry for the wall of text. My theory is that some ecosystems have a niche for pathogens that remain at low concentrations in healthy circumstances, but that become amplified in cases where the ecosystem is taking damage. The article you linked describes such an amplification: > “The Lyme disease bacterium has long been endemic,” she said. “But the deforestation and subsequent suburbanization of much of New England and the Midwest created conditions for deer ticks—and the Lyme disease bacterium—to thrive.”... > Ticks expanded into suburbanized landscapes—full of animals like white-footed mice and robins, excellent hosts for B. burgdorferi It may not have been humans that posed the initial differential threat to everything-but-the-mice-and-robins. But something did, and that created the pressure to arm mice and robins with invader-discouraging pathogens, and that pressure made B Burgdorferi what it is today. The increased pathogen concentration is an immune response. The stimulus is a reduction of predators (which are known to be more sensitive to habitat disruption) and the response is that the prey, left unchecked, amplify the pathogen and infect the invaders.

__MatrixMan__ 3y ago

I was perhaps too zoomed in on the details of how interspecies evolutionary pressure would work. Sorry for the wall of text. My theory is that some ecosystems have a niche for pathogens that remain at low concentrations in healthy circumstances, but that become amplified in cases where the ecosystem is taking damage. The article you linked describes such an amplification: > “The Lyme disease bacterium has long been endemic,” she said. “But the deforestation and subsequent suburbanization of much of New England and the Midwest created conditions for deer ticks—and the Lyme disease bacterium—to thrive.”... > Ticks expanded into suburbanized landscapes—full of animals like white-footed mice and robins, excellent hosts for B. burgdorferi It may not have been humans that posed the initial differential threat to everything-but-the-mice-and-robins. But something did, and that created the pressure to arm mice and robins with invader-discouraging pathogens, and that pressure made B Burgdorferi what it is today. The increased pathogen concentration is an immune response. The stimulus is a reduction of predators (which are known to be more sensitive to habitat disruption) and the response is that the prey, left unchecked, amplify the pathogen and infect the invaders.