Discovery Files

Genomes from 240 mammalian species reveal what makes the human genome unique

Parts of the human genome that have remained unchanged for millions of years shed light on diseases and unusual traits

Over the past 100 million years, mammals have adapted to nearly every environment on Earth. Scientists with the Zoonomia Project are cataloging the diversity in mammalian genomes by comparing DNA sequences from 240 species that exist today, from the aardvark and the African savanna elephant to the yellow-spotted rock hyrax and the zebu.

This week, in papers supported by the U.S. National Science Foundation and published in a special issue of Science, the Zoonomia team demonstrated that comparative genomics can not only shed light on how certain species achieve extraordinary feats, but also help scientists better understand the parts of our genome that might influence health and disease.

The researchers identified regions of the genomes, sometimes just single letters of DNA, that are most conserved, or unchanged, across mammalian species and millions of years of evolution — regions that are likely biologically important.

They also found part of the genetic basis for uncommon mammalian traits, such as the ability to hibernate or sniff out faint scents from miles away. And they pinpointed species that may be particularly susceptible to extinction, as well as genetic variants that are more likely to play causal roles in rare and common human diseases.

The findings come from analyses of DNA samples collected by researchers at more than 50 institutions worldwide.

More than 150 people across seven time zones have contributed to the Zoonomia Project, which is the largest comparative mammalian genomics resource in the world. The effort is led by Elinor Karlsson, director of the vertebrate genomics group at the Broad Institute of MIT and Harvard, and Kerstin Lindblad-Toh, a comparative genomicist at Uppsala University in Sweden.

"One of the biggest problems in genomics is that humans have a really big genome and we don't know what all of it does," said Karlsson. "This package of papers really shows the range of what you can do with these kinds of data and how much we can learn from studying the genomes of other mammals."