Mice have been used for scientific study since the 16th century, when William Harvey wanted to learn more about reproduction and blood circulation. Even after hundreds of years of technological innovation, the ordinary lab mouse is still the go-to option for learning more about our own species — and for good reason.

A large international consortium study recently found humans and mice have a lot in common in terms of how our genes are expressed and regulated. While mice don’t hold a candle to the genetic similarities of, say, the chimpanzee, whose genes are 96 percent similar to our own, the majority of the mouse’s genes that have endured through evolution are indeed “conserved” — meaning they serve the same functions after all these years — just as humans’ are.

“This is the first systematic comparison of the mouse and human at the genomic level,” said Dr. Bing Ren, a professor of cellular and molecular medicine at the University of California, San Diego, and a co-senior author of the new study, in a statement. Ren and an enormous team of colleagues from around the world found many of the processes and pathways are shared between humans and mice. “This allows us to study human disease by studying those aspects of mouse biology that reflect human biology,” he said.

Some differences were bound to show up. Immune system processes and some related to metabolism and stress response tended to differ in mice. That doesn’t mean, however, that scientists should be throwing out their studies on genes related to immune function and metabolism just because they used mouse models as their vehicle for investigation.

“That’s not the message we want to convey,” Dr. Feng Yue, first author of the study and Penn State University professor in the Department of Biochemistry and Molecular Biology, told Medical Daily. “We want to say that, indeed, mice are probably the best system to use for studying these two systems. But if you’re studying the immune system using mouse models you probably need to be more careful and perform more functional experiments. It’s not saying that their findings are wrong.”

The findings come on the heels of the ongoing mouse version of ENCODE — the Encyclopedia of DNA Elements — a parts list of the entire mouse genome that launched in 2007 as a way to complement the existing human ENCODE, which was published in full in 2012. In the latest study, researchers analyzed 100 different mouse cell types and tissues. They found many of the underlying processes (genomic functions) served the same purpose, but the mechanisms that let those things happen were different.

“In general, the gene regulation machinery and networks are conserved in mouse and human, but the details differ quite a bit,” said co-senior author Dr. Michael Snyder, director of the Stanford Center for Genomics and Personalized Medicine. But even though they may differ, what scientists care about is how they’re expressed. The trick is not getting lost in translation. “By understanding the differences,” Snyder added, “we can understand how and when the mouse model can best be used.”

That perhaps is the crucial point going forward. While mice models have been researched time and again for their differences to human models, scientists had yet to understand how they are different or how much they are different. Now they can use these important differences to pinpoint where similarities actually lie.

“By the most comprehensive studies,” Yue said, “we confirm it is, indeed, a good system to use.”

Source: Yue F, Cheng Y, et al. Nature. 2014.