Worried that the latest Pokémon generation wouldn't find much traction on North American store shelves due to their absence of titular color? Your fears were unwarranted -- within the first 24 hours of their launch, 1.08 million copies of Pokémon Black and White were sold, beating out the record of 780,000 units set by Pokémon Pearl and Diamond.
The reason for this growth? It probably has something to do with the fact that we keep getting older, but still love playing Pokémon, and also babies keep getting born, and eventually they love playing Pokémon too. That's no unnatural phenomenon -- that's basic physical anthropology.