How DNA tells history
Short facts that population genetics rests on, each with a reference source.
46 chromosomes
In humans, each cell normally contains 23 pairs of chromosomes, 46 in total. Twenty-two pairs, the autosomes, look the same in males and females; the 23rd pair, the sex chromosomes, differs between them.
MedlinePlus Genetics (U.S. National Library of Medicine): How many chromosomes do people have?
Mitochondrial DNA
Human mitochondrial DNA spans about 16,500 base pairs and contains 37 genes. Children inherit mitochondria, and with them mitochondrial DNA, from their mother, so it traces the maternal line.
MedlinePlus Genetics: Mitochondrial DNA; NHGRI Talking Glossary: Mitochondrial DNA
The Y chromosome
The Y chromosome spans more than 59 million base pairs, almost 2 percent of the DNA in cells. It is present only in males, which is why it is used to follow paternal lines.
Ancient DNA
Genomes recovered from ancient skeletons are published in scientific papers and gathered into curated databases. The Allen Ancient DNA Resource (AADR), which powers the maps on this site, is one such compendium.
Mallick S. et al. (2024). The Allen Ancient DNA Resource (AADR). Scientific Data 11, 182