Doing the Numbers

I put Necroscope: Defilers aside last night, in favour of Lyndall Ryan's The Aboriginal Tasmanians. Prosiac as a lot of history writing is, it's still a damn sight more interesting than page after slime dripping page of crepuscular cliches.

In the comments thread to this post over at Troppo Armadillo, Norman asks:

Why does Ryan suggest approximately 15% of Tasmania had been given to whites by 1820, when in fact grants totalled only 1/2 of one percent by then?

The implicit answer, of course, is that it's a historical beat-up, and that Keith Windschuttle was right all along. So let's take a quick look at Ryan's figures.

In Chapter 1, Ryan states that Tasmania has a total land area of 67,870 square kilometres (p 7 in my copy). At 100 hectares to the square kilometre that's 6,787,000 hectares. In Chapter 4 (p 78), she says:

Between 1811 and 1814, the area under cultivation increased from 3,332 hectares to 12,711 hectares, the number of cattle increased from 421 to 5,060 and the number of sheep from 3,573 to 38,540.

My calculations for these areas as percentages of the total land area of Tasmania are 0.04% and 0.18% respectively. The 15% claim is made at the end of chapter 4:

By 1820, the Europeans occupied less than 15 per cent of Van Diemen's Land, but already they had depleted the Oyster Bay and Midland tribes. [my emphasis]

This looks like a fairly big discrepancy, until we take the cattle and sheep into account. If we assume (as the outrage over the wide discrepancy between the area under cultivation and the area occupied by Europeans does), that all of the cattle and sheep were confined to the 12,711 hectares of land under cultivation, we end up with approximately 2 hectares for every cow, and 1/3 of a hectare for every sheep. That's a generous estimate, which ignores any areas set aside for agrarian production. I'm no agronomist, but unless the Tasmanian grasslands were exceptionally productive in 1820, I can't see that level of grazing being sustained in the long term. So maybe the reason Ryan suggests that the Europeans occupied so much more of the land than the recorded 0.18% isn't so sinister after all. How else could they feed the animals?