Nature.

In an experiment, I don't know yet.

Why is it like so far?

Like, it sounds so simple.

They had no idea.

But now the data's...

I find this not only refreshing, but at some level, astounding.

Nature.

Welcome back to the Nature podcast. This week we bring you news of the oldest ever hashtag. Plus the hidden energy costs of all your data. I'm Charmany Bundell. And I'm

Adam Levy.

About 300 kilometres east of Cape Town on the coast of South Africa is Blombos Cave.

It's a pretty small cave, only some 55 square metres in the area.

But this tiny cave has hidden huge secrets about the ancient humans that visited it.

Inside the cave, we have a perfect record of the activities that were carried up by those people during that time period from 70,000 to 100,000 years ago.

This is archaeologist Christopher Hensselwood.

Christopher's been excavating Blombos caves since the 90s, peeling back the layers of the past.

So it's like layers of a cake. As people came in, they did a whole lot of things and they left and the next people came in.

It's extremely rare. You can really count the number of sites like that on the fingers on one hand.

And from this rare sight, Christopher has uncovered remarkable finds, engravings on ochre dating to

75,000 years ago, beads that would have been worn as jewelry.

And then finally, in 2011, we published this toolkit from the 100,000-year levels, which

was a real breakthrough, because here you had perfectly preserved, two abalone shells,

...