Homo floresiensis or Oh no foolishness?

[CDarwin]

Ohohohoho

 

Apparently some new finds are casting "Homo floresiensis," the vaunted "Hobbit" from the Indonesian island of Flores, as simply a pathological human.

 

http://www.newscientist.com/channel/being-human/human-evolution/dn13441-new-bones-suggest-hobbits-were-modern-pygmies.html

 

I'm still not convinced either way, but I can recall hearing on a documentary some paleoanthropologist, it might have been Lee Berger, saying that "We all might look very foolish over this" and that's the sort of feeling I've had since I first started hearing about "H. floresiensis."

 

But what are the thoughts of ye distinguished of SFN?

[ecoli]

Last year, my evolution professor seemed pretty convinced that H. florensiensis was the real deal. I'm not sure what to think now. Unless we get some DNA, I don't think we're going to be able to tell easily.

[CDarwin]

Last year, my evolution professor seemed pretty convinced that H. florensiensis was the real deal. I'm not sure what to think now. Unless we get some DNA, I don't think we're going to be able to tell easily.

 

DNA isn't necessarily the end-all either. There are still people debating over whether-or-not Neanderthals and humans interbred even though Svante Pääbo's partial sequencing of Neanderthal mitochondrial DNA found it made no contributions to modern DNA.

 

I'm afraid people are getting this messianic picture of DNA and ignoring that it can be wrong just like anatomical studies can be wrong. But perhaps that's a bit off topic.

[ecoli]

I'm afraid people are getting this messianic picture of DNA and ignoring that it can be wrong just like anatomical studies can be wrong. But perhaps that's a bit off topic.

 

Well having DNA information certainly couldn't hurt. It would be interesting to see the structure of their growth hormones and things like that.

[Blue Fire]

I don't think all the evidence is in quite yet - there will surely be more excavations and finds to argue over. Note that the "new finds" that the OP mentions were found on a different island. And, the article at NewScientist also presents opinions that cast doubt on those casting doubt that Homo floresiensis is a new species of human. I'm sure the debate will continue in earnest in scientific circles to get at the truth even as media reports continue to hype all hints of controversy on such a unique subject as "hobbits."

[Mr Skeptic]

Well, there's the "island rule" that all animals on islands tend toward rabbit size. The smaller ones become bigger and the bigger ones become smaller. Humans certainly have genes affecting their size, and it shouldn't be too hard to make a small breed of humans if there were an advantage to it. So I'd say its definitely plausible, but it would be nice if they found a few more bones.

[CDarwin]

Well, there's the "island rule" that all animals on islands tend toward rabbit size. The smaller ones become bigger and the bigger ones become smaller. Humans certainly have genes affecting their size, and it shouldn't be too hard to make a small breed of humans if there were an advantage to it. So I'd say its definitely plausible, but it would be nice if they found a few more bones.

 

What you're referring to is the Wallacean Effect and it mostly only applies to mammals. Consider Komodo dragons or giant tortoises both of which are considerably larger than rabbit sized as a result of evolving on islands. That's obviously neither here nor there to you point; I just like being pedantic.

 

The Wallacean Effect could certainly play a role to "shrink" humans in island environments. The preponderance of modern human pygmies on Indonesian islands demonstrate this. But the presence of those pygmies belies the notion that such island effects must result in speciation.

 

I really think the anatomical studies are going to clinch this one. If more analyses come up with the same "primitive" features in the postcrania of floresiensis, I'll feel confident enough to believe that it is a separate species. I wish I had the technical acumen to be able to examine the studies already out there and come up with an opinion for myself.

[John Cuthber]

If I choose a random direction and walk far enough I get to the sea. This is

1 because I'm on an island and

2 true no matter where I am.

Since everywhere is on an island I can't see how the hypothesis is meaningful.

Define "Island".

[CDarwin]

If I choose a random direction and walk far enough I get to the sea. This is

1 because I'm on an island and

2 true no matter where I am.

Since everywhere is on an island I can't see how the hypothesis is meaningful.

Define "Island".

 

A true point. The Wallacean Effect occurs whenever an ecosystem is restricted into a relatively small, relatively isolated territory.

 

When a population of elephant goes from mainland Asia to an island on the Sunda Shelf, then suddenly the number animals that island can support becomes much smaller. Large population size is still advantageous to maintain genetic diversity, so the selective pressure is for smaller individual size.

[Blue Fire]

National Geographic Channel is running a special on the discovery of Homo floresiensis right now as I write. I think it has been on before and that I've seen it before, but there's always something ya miss the first time around.

[Daecon]

It couldn't just be an "ordinary" human who happened to be a Primordial dwarf?

[Blue Fire]

It couldn't just be an "ordinary" human who happened to be a Primordial dwarf?

I'd say that would be highly unlikely since remains of multiple individuals were found of widely varying ages at the time of death, each consistent with the diminutive size range of these people.

 

And, now this from SciAm Observations:

The Palau bones certainly underscore just how variable modern humans are. But do they really spell trouble for the theory that the Flores hobbits represent a new human species? I don't think so. Although Berger estimates that the Palau people had a brain size close to the low end of the modern human range, that's still a lot bigger than LB1's brain, which was on par with a chimp's. And hobbit critics have yet to come up with a genetic disorder that can account for LB1's diminutive brain size and all of her other odd traits. Furthermore, some aspects of LB1's skeleton are simply not found in H. sapiens. Her wrist bones, for example, look just like a chimpanzee wrist and nothing like our own. This is particularly strong evidence for LB1 belonging to a different species, because the wrist takes shape in the first trimester of pregnancy, well before most growth disorders could affect it. According to the National Geographic report, Berger's team has yet to study the wrist bones of the Palau folks.

 

One last tidbit: according to a story on ScienceNOW, other excavations on Palau have turned up individuals of normal body size that are the same age as the tiny people Berger found. To quote from the story:

 

"...archaeologist Scott Fitzpatrick of North Carolina State University in Raleigh, who has worked in Palau for a decade, says he doesn't think the bone beds represent a true population. In a site only 4 kilometers from Berger's caves, he has excavated the burials of Palauans of similar age--and normal stature. That would seem to rule out isolation and island dwarfing, he says. 'It would be very unusual to have a group of people living in close contact with a normal size population who evolved to be smaller.' Instead, 'the most parsimonious explanation is that they were Palauans with a genetic anomaly leading to small people who were buried in a clan or family plot.'"

From this it would seem that the "doubts" are still in favor of the "Hobbits".

[CDarwin]

I'd heard about Fitzpatrick's research too. When Berger discovered the Palau specimins he was basically just vacationing there, so he doesn't really have any history with the site. It's no surprise that he might jump to a conclusion without a full consideration of other finds that might have been made there.

[lucaspa]

Ohohohoho

 

Apparently some new finds are casting "Homo floresiensis," the vaunted "Hobbit" from the Indonesian island of Flores, as simply a pathological human.

 

The article doesn't do that. Instead, it says that there were pygmy H. sapiens also in Indonesia 1400 years ago. The new bones 1) aren't in the same time frame and 2) don't have the distinctive features of H. floriensis.

 

http://www.sciencemag.org/cgi/content/full/316/5821/34?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&andorexacttitle=or&andorexacttitleabs=or&fulltext=hobbit+people+Indonesia&andorexactfulltext=and&searchid=1&FIRSTINDEX=0&sortspec=relevance&fdate=7/1/1880&tdate=3/31/2008&resourcetype=HWCIT

 

"The diminutive human who lived on the Indonesian island of Flores 18,000 years ago has been called many things: a pygmy, a diseased Homo sapiens, a hobbit. Now, in a report that was the talk of the Paleoanthropology Society's annual meeting here last week, a postdoctoral researcher claimed that the shapes of the fossil's wrist bones are so primitive that it cannot be H. sapiens. "

 

The bones of the new finds have the shaped of H. sapiens, so the article implies.

 

"When Tocheri first saw casts of the hand bones at a lecture last fall, he was struck immediately by their primitive shape. In his Ph.D. dissertation from Arizona State University in Tempe--which he is defending this week--he used three-dimensional imaging to analyze an innovation in the modern human hand. Living people and our most recent ancestors possess a complex of five bones that mesh together to ease stress on the wrist when the hand is used forcefully, for example in pounding large tools or in precision work. Neandertals had this derived shock-absorber complex, too; it is first seen in the hand of an 800,000-year-old human ancestor, H. antecessor, from Atapuerca, Spain.

 

But the bony complex is not found in apes or earlier human ancestors, including H. habilis, which lived 1.75 million years ago in Africa. That species did use tools, but the shape of its hand bones does not distribute force away from the base of the thumb and across the wrist as efficiently as in modern humans.

 

Tocheri got permission to study high-quality casts of the Flores bones, which were made for Stony Brook University biological anthropologist William Jungers. What Tocheri saw confirmed his impression that three bones in the wrist closely resembled those of an ancient hominid, not modern humans.

 

Tocheri ruled out that the primitive hand bones were altered by disease because their distinctive shape develops in the first trimester, long before deformation from most diseases begins later in pregnancy or after birth. He also says known diseases do not reproduce the primitive bone shapes. "

 

"That fits with emerging evidence from the long limb bones, which show no pathology either, says Jungers (Science, 19 May 2006, p. 983)."