People also need to understand that all humans came from the same patrilineal ancestor known as Y-chromosomal adam and the same matrilineal ancestor known as mitochondrial Eve.
Y-chromosomal adam is considered to be the starting point of all the existing hyplogroups because every living human on this planet inherited his y-chromosome variant.
Now, you will find that Europeans are White, Africans are black and so forth. This is because of something called Single nucleotide polymorphism (SNP). This is the mutation that alters a single base pair in the DNA sequence.
Whenever the SNP mutation occurs, it leads to the evolution of a different hyplogroup. The mutation in one hyplogroup could lead to the evolution of another hyplogroup and this is what has been happening. Usually, this mutation occurs in mitochondrial DNA sequences (mtDNA).
Mutations have led to the evolution of people of different colors, physiological build-up and stature, etc. Just a single alternation in one base pair of the DNA sequence could lead to the single nucleotide polymorphism or SNP mutation.