Hobbit Humans Had Big Brains

Hobbit humans, the tiny folks who lived on the remote Indonesian island of Flores until about 12,000 years ago, had bigger brains than previously thought, according to a new paper that strengthens the theory that hobbits evolved from own own ancestor, Homo erectus.

Homo erectus, in turn, is thought to have evolved into our own species in Africa. The new study, published in the latest Proceedings of the Royal Society B, reveals how location and environment could mean the difference between an individual who looked like us, and someone who wound up a hobbit.

"They were extremely short (about 3'6"), much shorter than any healthy living humans," co-author Yousuke Kaifu told Discovery News. "Their legs were short relative to their arms and feet, (features that) some researchers think were primitive."

Kaifu, a senior researcher at the National Museum of Nature and Science in Tokyo, conducted the study with lead author Daisuke Kubo and Reiko Kono.

The three used high-resolution micro-CT scanning to study the brain regions of hobbit human skulls. The scans found that the brains measured 426 cc, as opposed to earlier estimates of around 400 cc. The former is still not huge by modern standards, and was about the same size as a chimpanzee's brain.

Nevertheless, the difference means it was possible for a Homo erectus population to have evolved such brains. The prior estimate ruled that out, since there is only so much shrinkage that could have taken place.

The researchers believe H. erectus, living on the mainland, either intentionally or unintentionally -- such as due to a storm -- made it to the isolated island of Flores.

The hobbits' "unique evolution suggests they did not go out of the island once they got there," Kaifu said.

He explained that "a popular theory is that big mammals tend to reduce and small mammals tend to increase their body sizes on an isolated island because of energetic demands."

Elephants, for example, tend to get smaller, since without many carnivores, they have no need to maintain such big, bulky bodies. Remains suggest that the hobbits hunted primitive elephants called Stegodon.

In contrast to the pygmy elephants, a type of stork and lizard evolved larger bodies on Flores, probably because predators were few and food was plentiful.

Known distribution of Homo erectus extends all the way from Africa to parts of Europe and Asia. Thus far, it looks like they could not survive the extreme cold of the North, but they did reach at least the one isolated island.

"So there are chances that they were also present on other near-shore islands of that region, such as Sulawesi and possibly the Philippines," Kaifu said.

Yet another likely regional population of Homo erectus, called "Peking man," inhabited the Asian continent, but it is still unclear if they evolved into more advanced humans or even interbred with Homo sapiens arriving from Africa. DNA analysis of what are known as Denisovans from Melanesia, Australia and the Philippines suggest that some interbreeding did indeed take place.

As for the hobbit human's contribution to the mix, much hinges on the brain size, given how that either strengthens or weakens the possible relationship to Homo erectus.

Dean Falk, whose team previously estimated the brain to be smaller, told Discovery News that the new measurement is “the most precise estimate available to date because it has been calculated with improved methods and great care." Falk, a Florida State University professor of anthropology, hopes that the "thoughtful and thorough analysis" will move "the discussion forward" about H. floresiensis.

William Jungers, professor and chairman of Stony Brook University Medical Center's Department of Anatomical Sciences, said, "this is the normal brain of a very small and now extinct human relative that evolved in isolation for at least a million years on Flores Island."

Read more at Discovery News