they may or may not actually be more retarded. but they certainly appear that way. this is because of temperature. it is an observable phenomenon that on any large contiguous body of land the appearance of intellectualism increases as you move north (or south in the southern hemisphere) and temperature decreases. people will look at europe and claim that these is an evolutionary reason for this, that the cold climates of northern europe required a more calm and contemplative temperament with longer time horizons in planning than the mediterranean areas, and this creates a character that has the appearance if not the reality of being more 'intellectual'. and there is a lot of truth in this. but it is not the full picture. this is because we see the same phenomenon play out in the new world. it is observable in both the americas and australia. if you want to conduct this analysis yourself then just remember to control for population size, as the larger a cities population the more 'intellectual' it will appear, so you must compare cities of similar population at different latitude. also the appearance of intellectualism differs greatly along longitudinal lines. in other words the us east coast and west coast must be looked at separately. i don't know exactly why this phenomenon occurs. some people think that different weather promotes different lifestyles, with colder weather promoting a more bookish and studious lifestyle, all else being equal. i also don't know if this phenomenon only reflects the appearance of intelligence or actual intelligence. in australia i would say that it really only impact the appearance of intelligence. victoria is the coldest of the east coast mainland states and appears to be more intellectually inclined but all that really means is that it is more faggy. there ability to actually think is arguably the weakest of all the states.
Australia