Smithsonian | 1.7-Million-Year-Old Rhino Tooth Provides Oldest DNA Data Ever Studied Read more: https://www.smithsonianmag.com/smart-news/million-year-old-rhino-tooth-provides-oldest-dna-data

DNA sequencing has revolutionized the way researchers study evolution and animal taxonomy. But DNA has its limits—it’s a fragile molecule that degrades over time. So far, the oldest DNA sequenced came from a 700,000-year-old horse frozen in permafrost. But a new technique based on the emerging field of proteomics has begun to unlock the deep past, and recently researchers extracted genetic information from the tooth enamel of a rhinoceros that lived 1.7 million years ago.

In traditional DNA sequencing, the molecule is run through a machine that amplifies the genetic material and is able to read off the sequence of nucleotides—adenine (A), cytosine (C), guanine (G) and thymine (T)—that make up the DNA strand and encode instructions to make amino acids and proteins. The quality and completeness of a genome depends on how well the DNA is preserved.

The new proteomics approach is essentially reverse engineering. Using a mass spectrometer, researchers look at preserved proteins and are able to determine the amino acids that make them up. Because researchers know what three-letter DNA sequence encodes each amino acid, they can then determine the DNA sequence for the protein.

“It’s reading DNA when you don’t have any DNA to read,” Glendon Parker, a forensic scientist at the University of California, Davis, says in a press release. He and colleagues are developing proteomics techniques that can be used in criminology, evolutionary biology and anthropology. “Protein is much more stable than DNA, and protein detection technology is much better now.”