When fossils of a diminutive, recently extinct race of humans were discovered in a cave on Flores, one of the most easterly islands of the Indonesian archipelago, researchers can be forgiven for assuming they were down-sized by the peculiar selection pressures that act upon insular species.

On Flores, natural selection has morphed several familiar species to unfamiliar sizes. There be dragons: three metre, 200kg monitor lizards, also known as the Komodo dragon, plus the fossilised remains of an extinct giant rodent, Spelaeomys, and extinct Stegodon pigmy elephants.

The tiny skulls of the Flores fossils ignited a heated, sometimes ad hominin, debate about whether they represented a new species of Homo, or were merely microcephalic mutants of a Floresian form of H. erectus, or even a microcephalic H. sapiens.

But a new cladistic analysis by an Australian National University PhD student suggests the diminutive, gracile humans who lived on Flores as recently as 12,000 years ago, now popularly known as 'hobbits', might not have been dwarfed by insular life.

Debbie Argue, of the Australian National University's School of Archaeology and Anthropology, has produced strong evidence that Homo floresiensis was tiny because its African ancestors were tiny.

If Argue is right, H. floresiensis descends from the first hominins to leave Africa, and this might have happened some 2.25 million years ago, around the time when the first, primitive Homo species was emerging in Africa.

If so, the hobbits' forebears could have colonised the Indonesian archipelago up to half a million years before the first large hominin species, Homo erectus - Java Man - crossed the deepwater gaps separating Java and Lombok, and Sumbawa and Flores, by means that did not involve swimming.