Why you don't really know what you know October 2020 What does it really mean to know anything? How well can we understand the world when so much of our knowledge relies on evidence and argument provided by others? These questions matter not only to scientists. Many other fields are becoming more complex, and we have access to far more information and informed opinions than ever before. Yet at the same time, increasing political polarization and misinformation are making it hard to know whom or what to trust.

But growing usable human tendon cells--which need to stretch and twist--has proved trickier. Over the past two decades, scientists have encouraged engineered tendon cells and tissue to grow and mature by repeatedly stretching them in one direction. However, this approach has so far failed to produce fully functional tissue grafts that could be used clinically, in human bodies. A new study, published in Nature Communications Engineering today, shows how humanoid robots could be used to make engineered tendon tissue that is more like the real thing. "The clinical need is clearly there," says Pierre-Alexis Mouthuy from the University of Oxford, who led the team.