Flores 'hobbits' revisited

darjeeling

The Flores 'hobbit' was in the news again last week with a couple of papers in Nature.

First dug up in 2003 on the Indonesian island of Flores and dubbed 'Homo floresiensis', the hobbits (bones from up to nine have now been found) were a little over a metre tall, and their remains date from around 95,000 years ago to 17,000 years ago. They had long forearms, long feet, vertical faces and small teeth - like ours - yet no chins, and very small brains for their size.

There's been a debate over whether they were pathologically stunted modern humans, or something much less closely related to us - possibly an island-dwarfed descendant of Homo erectus, which had reached Asia by 800,000 years ago, or an unknown hominin.

An argument against H. erectus ancestry was the hobbit's unusually small brain - just the size of a chimp's. Shrinking an H. erectus, it was thought, would give a larger brain. However, it's now been proposed that disproportionate brain shrinkage may be a common result of island-dwarfing - a Madagascan island-dwarfed hippo was seen to have a disproportionately small brain, as reported in Nature.

Also, the hobbit's unusually long feet have now been shown to have primitive apelike characteristics, meaning that their owner, while bipedal, wasn't cut out for running.

Jungers et al wrote:

The bony pelvis, lower-limb bones and feet of H. floresiensis combine to reveal an unequivocal adaptation to bipedalism, yet they also depart in functionally significant ways from the skeletal design of modern humans
[...]
The foot of H. floresiensis was not well-designed for either high-speed or efficient endurance running
[...]
the foot of H. floresiensis exhibits a broad array of primitive features that are not seen in modern humans of any body size. Primitive traits are also seen in the LB1 I]H. floresiensis[/I cranium, mandible, brain, shoulder, wrist, pelvis, limb bones and body proportions. It is conceivable that a few of these plesiomorphic traits could have evolved through reversals during approx 800 kyr of insular isolation on Flores, but it is improbable that all of them from head to toe were simply a consequence of 'island dwarfing'.
[...]
The comparative and functional anatomical evidence of the foot (and much of the rest of the skeleton) suggests that H. floresiensis possesses many characteristics that may be primitive for the genus Homo. It follows that if these features are primitive retentions, then H. floresiensis could be a descendant of a primitive hominin that established a presence in Asia either alongside or at a different time than H. erectus sensu stricto.

An accompanying 'news and views' piece, picks up on this.

Daniel Lieberman wrote:

[...] if the species evolved from early H. erectus, possibly like the fossils found at Dmanisi, then this species (or group of species) was more diverse and anatomically more primitive in many respects (hands and feet for example) than previously recognized. A more audacious hypothesis is that H. floresiensis evolved from an even more primitive species, perhaps H. habilis. If so, then this species also migrated out of Africa but left no trace yet found, except on Flores.

Consensus, then, is building that the hobbit wasn't a close relative of modern humans. A DNA sequence would prove it definitively, but the hot, damp climate makes it unlikely we'll get a bone preserved enough to yield good DNA. If the hobbit isn't human, it remains to be seen whether it was a descendant of H. erectus, or something even older that had found its way out of Africa independently.

[Edit: hominin family tree attached]

[Re-edit: and embedded]

Capt'n Midnight

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJS-4KKNDVW-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c21accf8da326c85450e659b087e62c5

However, notably less attention has been directed towards addressing the biological limits to increasing brain size. Here we explore variation in brain size in orangutans. We evaluated both raw and size-adjusted cranial capacity (CC)
...

The association of a relatively small brain and poor diet quality in Pongo further suggests that ecological factors may plausibly account for such a reduction in brain size as observed in the recently recovered Homo floresiensis from Indonesia.

darjeeling

The new-look Observer (now with added science) yesterday had a nice review of recent Homo floresiensis research.

It seems increasingly likely that the hobbit people left Africa and made their way half way round the world a million years or so before Homo erectus got out of the blocks. Previously it was thought that only a big robust and properly modern hominin like H. erectus would be able to do this, yet now it looks as though the hobbits got there first, despite their small size and inadequate feet.

You can read the piece here.

Wibbs

If what darjeeling noted is true that opens up an even bigger rethink of early hominids. Many scratched their heads trying to figure how erectus could have made the trip across open water. How more "primitive" hominids could do it makes this even more of a head scratcher. If proven then the books on the development of organisational intelligence will have to re written.

It is surprising though that the only evidence so far found outside of indonesia of the first out of Africa migration is that of erectus. Though according to that article they have found 2.2 MYA stone tools in nearby Sulawesi. :eek: That's unreal. You would think we would have similar or older aged tools along their migration route.

darjeeling

Wibbs wrote: »

If what darjeeling noted is true that opens up an even bigger rethink of early hominids. Many scratched their heads trying to figure how erectus could have made the trip across open water. How more "primitive" hominids could do it makes this even more of a head scratcher. If proven then the books on the development of organisational intelligence will have to re written.

It is surprising though that the only evidence so far found outside of indonesia of the first out of Africa migration is that of erectus. Though according to that article they have found 2.2 MYA stone tools in nearby Sulawesi. :eek: That's unreal. You would think we would have similar or older aged tools along their migration route.

There does seem to be a rewrite of the early out-of-Africa story going on. We now have the primitive-looking Homo georgicus from Dmanisi, Georgia dating to around 1.8Mya, crude stone tools from China at about the same time or earlier, and now the possibility that the Flores 'hobbits' were an offshoot from the hominin tree dating substantially earlier than Homo erectus.

A 2005 Nature review paper (here, for those with access) brought these three sets of finds together and concluded:
"it is time to develop alternatives to one of palaeoanthropology's most basic paradigms: 'Out of Africa 1'"

Wibbs

More going on it seems. Earlier tools found. Million years old. http://news.bbc.co.uk/2/hi/science/nature/8574037.stm