A new study has found that more than a million single-letter variations in human DNA reveal that in evolutionary terms, most genetic mutations originated fairly recently.
These kinds of mutations change one nucleotide - an A, C, T or G - in the DNA sequence. Over 86 percent of the harmful protein-coding mutations of this type arose in humans just during the past 5,000 to 10,000 years.
Nucleotides are biological molecules that form the building blocks of nucleic acids (DNA and RNA) and serve to carry packets of energy within the cell (ATP), the journal Nature reports.
Some of the remaining mutations of this nature may have no effect on people, and a few might be beneficial, according to project researchers.
While each specific mutation is rare, the findings suggest that the human population acquired an abundance of these single-nucleotide genetic variants in a relatively short time.
"The spectrum of human diversity that exists today is vastly different than what it was only 200 to 400 generations ago," said Joshua Akey, associate professor of genome sciences at the University of Washington, Seattle, who co-authored the study with colleague Wenqing Fu, according to a Washington statement.
He is one of several leaders of a multi-institutional effort among evolutionary geneticists to date the first appearance of a multitude of single nucleotide variants in the human population.
The work stems from collaboration among many genome scientists, medical geneticists, molecular biologists and biostatisticians at the UW, the University of Michigan, Baylor College of Medicine in Houston, the Broad Institute at MIT and Harvard, and the Population Genetics Working Group.
The study is part of the Exome Sequencing Project of the National Heart, Lung, and Blood Institute at the National Institutes of Health.