currency

[Eway]

...Shettles was close to no one, so isolated in his work that he kept no lab notebooks, the common currency of scientific collaboration, insisting that he had all the details safely inside his own head...

What does it mean by "the common currency of scientific collaboration"?

[Casiopea]

Keeping notes of one's experiments is the regular or usual way that ideas and theories are passed from one scientist to another.