Fu and her team are working on displaying the long process through extracting information from more materials and traces, such as ancient dental calculus and pathological bone samples.

"This work is not only based on our own interests, but more importantly, it may provide important genetic information for us to understand the health problems of modern humans," Fu says.

"At the same time, understanding the process of coevolution of ancient humans and microorganisms will also shed some light on modern or future human adaption to the environment."

What Fu hopes to pass onto younger scholars and students is a skeptical spirit.

Whenever she is about to overturn an existing result, she says her first response is not excitement, but suspicion of a possible mistake on her part.

The self-doubt only goes away through a process of constant faultfinding and authentication.

"I encourage them (students) to make an attempt at challenging authority, and then test and verify over and over again," she says.

"Many breakthroughs come from moments like this."