Environmental changes have always had a profound impact on the evolution of species. The advent of cities like NYC, have especially brought along swift environmental changes, steering evolution in a completely new direction. White footed mice for example, originally brought along by European settlers, have now become accustomed to urban stress, and have adopted from living in forests to modern day buildings. Scientists have also identified mutations in more than 1,000 genes in NYC mice, as compared to mice from other parks upstate.