Claim: In evolutionary terms, the urban environments we take for granted represent radical ecological upheavals, the sort of massive changes that for most of Earth’s history have played out over geological time, not a few hundred years.
Reason 1: This is new, and animals are adapting, all around us.
Backing:
"A growing body of scientific evidence suggests that the brains and behaviors of urban animals are changing rapidly in response." (assertion of facts)
Reason 2: The adaptable early immigrants, and other species that once avoided cities but are slowly moving in, are changing fast.
Backing:
"Museum specimens gathered across the 20th century show that Minnesota’s urbanized small mammals — shrews and voles, bats and squirrels, mice and gophers — experienced a jump in brain size compared to rural mammals."
"Snell-Rood thinks this might reflect the cognitive demands of adjusting to changing food sources, threats, and landscapes." (assertion of facts)
Reason 3: Urban animals tend to be bold, not backing down from threats that would send their country counterparts into retreat.
Reason 4: The city’s salamanders tend to be languid.
Reason 5: Muted stress responses have been found in many species of urban animals. When surprised or threatened, their endocrine systems release lower-than-usual amounts of stress hormones.
Backing:
“They’re clearly attenuating their physiological response to stress, probably because they’re constantly inundated with noise, traffic, and all kinds of environmental stresses in cities,” said biologist Jonathan Atwell of Indiana University. (use of scientific source)
Reason 6: The San Diego juncos sing at higher frequencies than those living in rural, traffic-free settings.
Reason 7: Urban squirrels, for example, seem to have adjusted to vocalization-drowning ambient noise by making tail-waving a routine part of communications.
Refutation 1: Not all changes in urban animals will represent adaptations to urban living, however.
Backing:
"Most genetic mutations are neither beneficial nor harmful, at least not right away. They simply happen and, over long periods of time, accumulate in populations through what’s known as genetic drift."
Reason 1: This is new, and animals are adapting, all around us.
Backing:
"A growing body of scientific evidence suggests that the brains and behaviors of urban animals are changing rapidly in response." (assertion of facts)
Reason 2: The adaptable early immigrants, and other species that once avoided cities but are slowly moving in, are changing fast.
Backing:
"Museum specimens gathered across the 20th century show that Minnesota’s urbanized small mammals — shrews and voles, bats and squirrels, mice and gophers — experienced a jump in brain size compared to rural mammals."
"Snell-Rood thinks this might reflect the cognitive demands of adjusting to changing food sources, threats, and landscapes." (assertion of facts)
Reason 3: Urban animals tend to be bold, not backing down from threats that would send their country counterparts into retreat.
Reason 4: The city’s salamanders tend to be languid.
Reason 5: Muted stress responses have been found in many species of urban animals. When surprised or threatened, their endocrine systems release lower-than-usual amounts of stress hormones.
Backing:
“They’re clearly attenuating their physiological response to stress, probably because they’re constantly inundated with noise, traffic, and all kinds of environmental stresses in cities,” said biologist Jonathan Atwell of Indiana University. (use of scientific source)
Reason 6: The San Diego juncos sing at higher frequencies than those living in rural, traffic-free settings.
Reason 7: Urban squirrels, for example, seem to have adjusted to vocalization-drowning ambient noise by making tail-waving a routine part of communications.
Refutation 1: Not all changes in urban animals will represent adaptations to urban living, however.
Backing:
"Most genetic mutations are neither beneficial nor harmful, at least not right away. They simply happen and, over long periods of time, accumulate in populations through what’s known as genetic drift."
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