I’d be interested, but evolution over the past 20,000 years doesn’t affect the argument I’m making here, which looks at a long-term trend in evolution.
ADDED: There are some factors that will increase genetic exchange and selective pressure, as discussed in some comments below; but not that increasing genetic exchange often slows evolution. There’s a balance between being able to spread beneficial mutations, and reaching premature convergence; the “sweet spot” of that balance is with very small communities, much, much smaller than continent-sized. Some equations and data indicate that species diversity is much larger when the environment is fragmented into small areas with little communication (google “island theory of biogeography”).
I’d be interested, but evolution over the past 20,000 years doesn’t affect the argument I’m making here, which looks at a long-term trend in evolution.
ADDED: There are some factors that will increase genetic exchange and selective pressure, as discussed in some comments below; but not that increasing genetic exchange often slows evolution. There’s a balance between being able to spread beneficial mutations, and reaching premature convergence; the “sweet spot” of that balance is with very small communities, much, much smaller than continent-sized. Some equations and data indicate that species diversity is much larger when the environment is fragmented into small areas with little communication (google “island theory of biogeography”).