Until recently, I found out that the mitochondria are not merely the energy currency makers of the body, they are much more. Various genes in mitochondria and various mutations in these genes lead to the formation of various mtDNA haplotypes.
These haplotypes or haplogroups determine the metabolic rate of the body, the athletic ability, the ability to with stand cold and even longevity.
So, next time you meet a person who feels colder in the freezing winter nights as compared to you, show off some mitochondrial DNA haplogroups knowledge !!!!