File under 'stuff the aliens taught us'
I was going to use a stronger word than 'stuff' but I'm occasionally afflicted by fits of propriety. Anyway.
Human beings are amazing:
More impressive still, about half of the island is covered by "lithic mulching," in which the islanders scattered broken stone over the fields. The uneven surface creates more turbulent airflow, reducing daytime surface temperatures and warming fields at night. And shattering the rocks exposes "fresh, unweathered surfaces, thus releasing mineral nutrients held within the rock." Only lithic mulching produced enough nutrients - just barely - to make Rapa Nui's terrible soil cultivable. Breaking and moving vast amounts of stone, the islanders had engineered an entirely new, more productive landscape.
From an interesting review of a book about Easter Island (via).
{2011.07.30 22:25}