Researchers who studied the bones of Homo floresiensis, a species of tiny human discovered on the Indonesian island of Flores in 2003, say their findings should end a popular theory that it evolved from an ancestor of modern humans.

Diminutive humans that died out on an Indonesian island some 15,000 years ago were not Homo sapiens but a different species, according to a study published Monday that dives into a fierce anthropological debate.

It was the 18th-century scientist Carolus Linnaeus that laid the foundations for modern biological taxonomy. It was also Linnaeus who argued for the existence of Homo troglodytes, a primitive people said to inhabit the caves of an Indonesian archipelago.

Human beings have come to dominate our planet like no other creature before us. Today, our seven-billion-strong population inhabits most of the surface of the world, secure in its status as the only truly intelligent species on Earth.

Yet if we look even a little way back into the planet’s history, we come to a time – possibly as recently as 50,000 years ago – when there may have been as many as seven distinct types of human, from Africa to Europe to the wilds of Siberia and the remote islands of Indonesia. We, Homo sapiens, are the sole survivor of this menagerie – but for most of human history, we were not alone.

For much of the past five million to seven million years over which humans have been evolving, multiple species of our forebears co-existed. But eventually the other lineages went extinct, leaving only our own, Homo sapiens, to rule Earth. Scientists long thought that by 40,000 years ago H. sapiens shared the planet with only one other human species, or hominin: the Neandertals. In recent years, however, evidence of a more happening hominin scene at that time has emerged. Indications that H. erectus might have persisted on the Indonesian island of Java until 25,000 years ago have surfaced. And then there's H. floresiensis—the mini human species commonly referred to as the hobbits—which lived on Flores, another island in the Indonesian archipelago, as recently as 17,000 years ago.

Now researchers writing in the journal Nature report that they have found a fifth kind of hominin that may have overlapped with these species. (Scientific American is part of Nature Publishing Group.) But unl