Mitochondrial Eve

Mitochondrial Eve refers to the woman believed to be the mother source of the mitochondria found in humans today.  Because mitochondrial DNA is passed solely through the mother, theories suggest that early in evolutionary history there was one common ancestor.  From her descendants, many tribes spread throughout the world and evolution 
led them towards characteristics that would best suit them to inhabit the regions to which they had migrated.

The many cultures across the globe provide examples of the great diversity that originated from a single source. 

These people are citizens of the Democratic Republic of the Congo:

These people are from further north on the continent of Africa, from Egypt:

This is a picture of schoolchildren in Seoul, south Korea:

This woman and child are inhabitants of Brazil:

This elderly woman is from Russia:

The Native Americans were the original inhabitants of North America prior to the arrival of European influences:

  

Despite the many variations of human physiology depicted in these portraits, modern times allow travel and immigration much more readily than in times past.  This easier access makes it more common for people of different cultures and races to marry and reproduce.  Thus, it is more and more common to see people who display a myriad of cultural traits.  It is not unreasonable to assume that in the coming centuries the people of the world will continue to converge and return to a kind of global "norm" of features with less distinction from one location to the next.