How useful is the information you get from the measure of any thing? That depends on what you chose measure in the first place, and that's not always clear.
The international prototype kilogram keeps changing weight so scientists have come up with a new way to calculate.
From sundials to atomic clocks, a journey through the way humans have measured time.
The big question being asked is: where does Homo naledi fit in the evolutionary tree? Assessing the similarity or dissimilarity between fossil skulls has provided a possible clue to the answer.