Robin Williams

Let's start with fire.

If you were to go to a landscape and take some samples...

Presumably you're doing it in the soil and places like that.

Can you tell something about the fire history of that region?

Not from the soil, but from a lake that's right next to it.

So lakes are little tape recorders, so they accumulate sediment from the bottom up.

You go and you take your lake core and within that core there's charcoal that came from those fires and a lot of people count the charcoal to see how much fire was there.

If you add the isotopes for the charcoal and you can tell what was burning, was it a grassland or was it a forest?

And that in turn relates back to climate.

And what we've shown in the Northern Territory is that you can use the isotopes and other measures to show that indigenous fire regimes were established there at least 11,000 years ago and possibly 40,000 years ago.

Do you mean it started possibly 40,000 years ago and continued until 11,000 years ago or what?

potentially started 40,000 years ago.

We don't have all the markers back that far from 11,000 years ago.

We can definitively say that the sort of cool burning that Aboriginal people did up here in this part of the world was established and was maintained through till European invasion.

You see a difference 11,000 years ago in the samples.

Yes, basically the isotope composition changes so you see more grass burning and we know from the pollen what the total vegetation was.

And so we can say it was the grass burning, it wasn't hot fires, which is what you tend to get without humans or with European humans.

So that change, which is unique in 150,000 years, can be reliably attributed to indigenous fire management.

So that was a sophisticated way of treating the landscape, even those many thousands of years back.

Yes, it was managing the land for biodiversity, for safety, really, for promoting food resources, animal and plant.