[bnjemian]

I don't know if this is true – that pupil sizes vary meaningfully between races and folks from Africa and Aboriginal populations in Australia have smaller pupils – but it may make sense. Those are both relatively sunny places; Northern latitudes are less so. Greater dilation (or dynamic range around the dilation), more light, possibly improving certain aspects of vision in low light. Of course, the inverse may also hold – less ability for pupils to constrict in very sunny places would be problematic too. And yet, I say this knowing that hypotheses derived from first principles and uninformed of biological context tend to be very low mileage in the biological sciences. Biology is rarely so simple.