Using Students' Own DNA Sequences to Explore Human Evolution

Although people may look rather different on the outside, genetic analysis shows that all humans are closely related. DNA studies confirm that all people alive today share a common ancestor in Africa about 150,000 years ago, and that we interbred with ancient Neanderthals and a mysterious group called the Denisovans. This seminar introduces an integrated biochemical and bioinformatics workflow that allows students to use their own DNA as an entrée to the study of human evolution. Students learn how DNA sequence polymorphisms are used as a molecular clock to discover relationships between modern populations and ancient hominids.

DNA from the hypervariable region of the human mitochondrial (mt) genome is isolated using almost foolproof methods for Chelex DNA extraction and PCR amplification. The PCR products are sent by overnight mail to our partner, Genewiz, where sequences are generated ($3 per read) and automatically uploaded to our server within 48 hours. Either of two educational interfaces – Bioservers or DNA Subway– are used for multiple sequence alignments between student samples, sequences obtained by BLAST searches, or reference sequences from modern human populations, ancient hominids, and other animals. The web accessible tools include an electropherogram viewer, a “barcode” alignment viewer, and tree building by neighbor joining and maximum likelihood methods.

The experiment can readily be performed in the context of introductory biology or genetics courses. Since its development in 1997 more than 110,000 mt DNA sequences have been uploaded to the student database, and the bioinformatics sites have received 1.6 million visits.