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Wednesday, October 27, 2004

Homo floresiensis, Flores Man

Echoed on the Panda's Thumb

A long-lost cousin has been discovered, Homo floresiensis, or Flores Man. It's especially dramatic for a number of reasons. It's relatively recent, with the youngest specimen only 18,000 years old, but it is most closely related to Homo erectus. This species was also minute, only 3 feet tall, and tiny-brained. Here we have a group of small, specialized human relatives, living contemporaneously with Homo sapiens, on isolated islands in Indonesia. It's like discovering that Munchkins were real. You can read more here:

Flores Man
The LB1 cranium and mandible in lateral and three-quarter views, and cranium in frontal, posterior, superior and inferior views. Scalebar, 1cm.

A real pleasure of working in a historical science like biology is that sometimes you can be completely surprised by some unexpected, odd, and entirely accidental discovery. Flores Man is such a wild surprise.

A new human-like species - a dwarfed relative who lived just 18,000 years ago in the company of pygmy elephants and giant lizards - has been discovered in Indonesia.

Skeletal remains show that the hominins, nicknamed 'hobbits' by some of their discoverers, were only one metre tall, had a brain one-third the size of that of modern humans, and lived on an isolated island long after Homo sapiens had migrated through the South Pacific region.

"My jaw dropped to my knees," says Peter Brown, one of the lead authors and a palaeoanthropologist at the University of New England in Armidale, Australia.

The find has excited researchers with its implications—if unexpected branches of humanity are still being found today, and lived so recently, then who knows what else might be out there? The species' diminutive stature indicates that humans are subject to the same evolutionary forces that made other mammals shrink to dwarf size when in genetic isolation and under ecological pressure, such as on an island with limited resources.

Flores Man adds an interesting twist to our hominid phylogenies. As you can see in this diagram, we now have to add this slender thread from the great Homo erectus dispersal, a relic species that survived long after it's closest relatives.

Flores Man
Homo floresiensis in the context of he evolution and dispersal of the genus Homo. a,The new species as part of the Asian dispersals of the descendants of H. ergaster and H. erectus, with an outline of the descent of other Homo species provided for context. b, The evolutionary history of Homois becoming increasingly complex as new species are discovered. Homo floresiensis (left) is believed to be a long-term,isolated descendant ofJavanese H. erectus, but it could be a recent divergence. 1, H. ergaster/African erectus; 2, georgicus; 3, Javanese and Chinese erectus;4, antecessor; 5, cepranensis; 6, heidelbergensis; 7, helmei; 8, neanderthalensis; 9, sapiens; 10, floresiensis. Solid lines show probable evolutionary relationships; dashed lines, possible alternatives.

Cryptozoologists are going to have a ball. Henry Gee already has an article up, mentioning "that other species of recently extinct humans might be discovered on other isolated islands", and even mentioning the possibility of extant hominids.

The accompanying paper on the archaeology also shows the tools found with these little hominids; these weren't simple apes. They were making some wicked weapons and carving tools.

Flores tools

Despite its ability to make tools, though, Flores Man was small-brained, small even for its diminutive size.

brain/body ratios
The relative brain and body size of H. floresiensis. The dimensions of the skull and skeleton (LB1) described by Brown et al. fall well outside the extremes seen in H.sapiens and the ‘erectines’(a range of hominin species, of which H. erectus is the most familiar). LB1 is closer in size to, but even smaller than, the australopithecines, of which the best known example is Lucy. On various anatomical grounds,however, Brown et al. believe that LB1 represents a dwarfed H.erectus.

Look at that: 1m tall, with a 380 cm3 brain. And shaped stone tools. That is simply amazing.


Flores Man reconstruction

There's also an article on Flores on the National Geographic site, including the nice reconstruction to the left.

National Geographic provided funding for the research, and are going to be airing a documentary on the subject next year.


They also summarize the little guy's life style:

The Flores people used fire in hearths for cooking and hunted stegodon, a primitive dwarf elephant found on the island. Although small, the stegodon still weighed about 1,000 kilograms (2,200 pounds), and would pose a significant challenge to a hunter the size of a three-year-old modern human child. Hunting must have required joint communication and planning, the researchers say.

Almost all of the stegodon fossils associated with the human artifacts are of juveniles, suggesting the tiny humans selectively hunted the smallest stegodons. The Flores humans' diets also included fish, frogs, snakes, tortoises, birds, and rodents.

Morwood MJ, Soejono RP, Roberts RG, Sutikna T, Turney CSM, Westaway KE, Rink WJ, Zhao J-x, vandenBergh GD, Rokus Awe Due, Hobbs DR, Moore MW, Bird MI, Fifield LK (2004) Archaeology and age of a new hominin from Flores in eastern Indonesia. Nature 431-435.

Brown P, Sutikna T, Morwood MJ, Soejono RP, Jatmiko, Saptomo EW, Rokus Awe Due (2004) A new small-bodied hominin from the Late Pleistocene of Flores, Indonesia. Nature 431:1055-1061.


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Comments:
#9951: — 11/29  at  09:04 PM
H. floresiensis anyone?



#9954: — 11/29  at  11:12 PM
Only two generations ago there were still a few Aborigine Pigmies surviving in the rainforests of Northern Australia. They were collected in missions and soon disappeared by mixing with regular Aborigines. I have seen pictures of these naked folks and they were very small, about the H. floresiensis size. No one ever suggested that they were not sapiens, but could they have been related to the Flores people?



#9958: — 11/30  at  02:04 AM
I imagine so. One of the shock-horrors of the whole Australia/Sulu thing is that H. sap. appears to have a wider variation than some palaeos would like. It's useful for those needing grants to show that they've got a new species, and I'm all for that; but when it comes down to the real basis of a species, breeding is what counts. Late H. erectus appears to have been genetically human, as were all the people who descended from them. Human males will mate with anything warm that has a hole in it, so genetic isolation in that area never had a chance.
While I'm on that soapbox, I'll point out that the extraction of DNA from bones in a cave is always going to produce "non-human" results because bones, being very porous, absorb bat DNA from the soil. Any of you who has excavated a cave site will know the smell. The Neanderthal DNA scam does no credit to the science or the academics who perpetrated it.



#10039: — 12/01  at  03:21 AM
H. sap. appears to have a wider variation than some palaeos would like.
I definitely agree here. The variety seen in our human population today should convince anyone that we are a wonderfully diverse species! Not only in our appearance, but in our diet (from the high blubber and meat diet of the frozen north to the vegan delights of Marin, California), in the oxygen-carrying capacity of our blood (peoples in high altitudes), in our social groups and languages, and in so many other ways. Wow!
And when I think of we poor paleoanthropologists who only have bones and teeth to go by...well, it is just difficult sometimes to sort out the evidence. Add to that the fact that bone is such a plastic material, able to morph fairly quickly under selective pressures, and you get a picture that is not always the clearest vision of our ancestors. However, recognizing (as did Ajaan) that humans will mate anytime, anywhere, and under many circumstances (as I tell my students), I just don't see the need to make a new species out of every variant that we see. (Are you listening, Milford?) smile
Although our past reveals a busy tree full of ancestors, modern humans have done an astounding amount of adaptation!



#10120: — 12/02  at  02:16 AM
Too right we have. Aleuts and Australians have been separated for anyhow 100,000 years, yet are members of the same species. Some ancient Aleuts had sagittal crests (ridges down the middle of the cranium for attachment of powerful jaw muscles) and some ancient Australians had big brow ridges and receding jaws; but those were racial variants, not indicators of speciation.
What maintains the species' genetic integrity, I suspect, is the wandering of exceptional individuals. I met a trader in Mae Hongsorn, NW Thailand, who walked from India to Thailand and back every year trading herbs, stones and other local produce. By 3500BC Southeast Asian goods were being traded to the Caucasus and Egypt. In the Pacific, a navigator named Toi is credited with visits to a large number of widely-separated islands. And of course Malay navigators colonised Madagascar and populated it with the offspring of African women they brought from the continent. Populations move slowly, but individuals and gangs are like lightning. That's what has kept us as one species.



#10122: — 12/02  at  04:54 AM
Speciation requires more than 100,000 years for an animal with such an ungovernable interbreeding urgency as ours. Born with an embedded program to breed anywhere, anytime, with anyone, at any cost, racism in Homo sp. has no future.



#10387: — 12/07  at  02:02 PM
Ajaan and GG: Good stuff, especially about the crest in Aleuts. I would also agree with you about why we continue to be one species. Morris might be right that the most salient human trait is an abundant sexual appetite.

Striped Ursine: I prescribe excessive handwringing for your problem.



#10430: — 12/07  at  11:49 PM
To fight boredom while we are waiting for more data on the Flores person, does sagittal keeling found in eskimo skulls impact the argument that Flores is not H. sapiens but something else? What about nuchal crests? Could microcephaly or some other condition of pathological dwarfism explain Flores?



#10436: — 12/08  at  01:33 AM
They certainly look like a separate species to those of us used to the speciation applied to African hominids; but if there had been no living Aborigines in Aussie when the English invaded, you can be sure that there would have been at least three species of Homo identified there from cranial evidence.
Indeed, if human palaeontologists (or, worse, entomologists) were put in charge of dogs for a week we'd have several genera and over a hundred species to deal with.
The chance of bones being preserved in the humid tropics is so small that they may never find any others. It's reasonable to assume that people who could get to Flores could also get to New Guinea, but the chance of finding remains there is miniscule. People must have been there for tens of thousands of years at least, but no skeletal remains have been found. I've seen stone tools in Thai limestone caves which, in the light of their context, must date from the last interglacial, but no one has excavated any of that stuff because it's so bloody hard to get at. Much easier to dig where it's dry, which is why nearly all research on early man sticks to deserts, or locations within easy reach of a hotel.



#10690: — 12/10  at  12:40 PM
The "species breeding" thing causes me to wonder. If mules are sterile and numbers of chromosomes have to match up, how is it that we get occasional cross pollenation? Several years ago the aquatic mammal folks in CA's Channel Islands were alarmed at "murdered" cows. Apparently, there was a mutant pinniped which was a freak cross breed who was crushing the cows while mating. Apparently, as a much larger male, he was quite dominant (like Brad) and had killed dozens of females in a futile attempt to breed. How many other other odd crosses are there running, or swimming, around?



#11078: — 12/14  at  02:04 PM
If mules are sterile and numbers of chromosomes have to match up, how is it that we get occasional cross pollenation? (sic) and there was a mutant pinniped which was a freak cross breed
Hi Richard! Just a comment here: pollination refers to plants, and plants are a whole other story when it comes to making hybrids and polyploidy (chromosome doubling). (You may already know this and were just using literary license!)
Animals aren't that simple. I haven't heard of the pinniped beast you speak of...was it a cross between two related marine species, or just an oversized animal?
Regarding our hominid ancestors, it is interesting to remember that the gorilla and chimpanzee line have the ancestral condition of 24 chromosome pairs, while we humans diverged when two of those chromosomes combined into one, leaving us with just 23 pairs. Because of this, it is unlikely that any hominid could have interbred with any ape after that chromosome change occurred. It is also evidence for the chimpanzee representing the ancestral line from which we diverged some 7 (or 8 or 9)million years ago!



#11086: — 12/14  at  03:04 PM
GG: Yes, having three children, I suspected that it wasn't pollen doing the jobsmile, but as to the pinniped, he was apparently a cross and roughly twice as heavy as the "correct" male. This was between '93 and '98.

Now, being someone who likes to stuff different engines in odd vehicles, I wonder a lot about adapter parts. I wonder if we could find a sort of "filler" chromosome to match up for entertaining hyjinks? This whole DNA thing is just too much fun to speculate about.

Has there ever been a successful (live birth) cross between animals with different chromosome numbers? I mean, we all know that lions and tigers can breed, but how about hyenas and tigers or leopards? Is there anywhere on the net where the numbers of chromosomes per critter is listed. You know, maybe the Horned Western Grebe or something has the same number as a, oh s&%t, say an ostrich....?

Is the idea of crossing critters for the sake of entertainment (Scientist: "Oh, cool! Will you look at that!") immoral?

By the way, I'll bet you're at the top of all your friends' "A" party lists.



#11848: — 12/24  at  11:58 AM
Richard: I don't think I have friends with party lists (I'm usually the one who invites them, disparate characters that they are!) I'm sure you'd fit right in! smile

Anyway, continuing wih the subject at hand (genetic crosses between animals with differing chromosome numbers)...
I don't know of any examples just off hand, but I believe that in the invertebrate world it has happened, presumably using invertebrates whose larval forms, once crossed, produce chimeras, or genetic mosaics. Apparently larvae can withstand this, and it has been put forth as a mechanism for rapid evolutionary change (punctuated equilibrium theory), such as that seen in sympatric speciation in marine inverts particularly.

Hey everyone, have a wonderful Christmas holiday, and let's all work for World Peace.



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