Hobbits of Flores: Expert Q&A

Q: Is there a relationship between size of brain and intelligence? Grant, Morgantown, West Virginia

Roberts: This is certainly thought be an approximate rule-of-thumb, but in detail the relationship is not exact. For example, Neanderthals had brains at least as large as ours, but they did not engage in any of the artistic pursuits—such as cave paintings—favored by their Homo sapiens contemporaries. And the tiny size of the hobbit brain sorely tests the myth that big equals brighter.

It would appear, based on the study of the hobbit brain published recently in Science by Dean Falk and colleagues, that our intelligence is defined more by the way the brain is wired than by its sheer size. But the matter is far from settled, and it will remain an open question until we have a better grip on what the hobbit could and could not accomplish with a brain the size of a grapefruit!

Q: If the little people of Flores were still alive, in what part of Flores would be more likely their home? And what are some of the factors that determine that? Anthony, Boise, Idaho

Roberts: Homo floresiensis probably inhabited the rain forests, living a hunter/gatherer lifestyle. Most of Flores is now cleared land, and there are only a very few pockets of original rain forest remaining. But if I were serious about looking for one of these little people, then that is where I would head!

Q: Do you disagree in any way with the views expressed by Jared Diamond (see Jared Diamond on the Hobbit)? Charles Kendall, Bloomington, Minnesota

Roberts: My main point of disagreement with Jared Diamond is whether Homo sapiens quickly extinguished the hobbits soon after we made landfall on Flores (Jared's position) or whether there was several thousand years of overlap (the view of many of the research team). It is worth bearing in mind that these are just opinions we are expressing, not matters of fact, because we have no strong basis for settling the matter one way or the other at the present time! I responded a little to this issue in my earlier reply to Marek's question, but I'll expand a little more here on a teasing dichotomy.

On the one hand, we have hobbits living on Flores from at least 95,000 years ago to 12,000 years ago, with the first unequivocal evidence for modern humans on Flores from about 11,000 years ago. We have much earlier evidence, from skeletons and skulls, of modern humans in Borneo (Niah Cave) and Australia (Lake Mungo) by 40,000 years ago. So we can say with certainty (or as much as one can have when reconstructing events in the prehistoric past) that our species was dispersed throughout Southeast Asia by at least 40,000 years ago, if not earlier. (The oldest stone tools in Australia are 50,000 to 60,000 years old, but there are no associated human remains.)

It seems inconceivable to me that a "weed species" such as ourselves never stumbled across Flores before 11,000 years ago, having been in the general vicinity for the preceding 30,000 years, if not longer. Surely we must have done; but we need the sites and skeletons on Flores to this validate this proposition. If proven correct, then Homo sapiens and Homo floresiensis must have co-existed on the island for several tens of millennia.

On the other hand, Jared takes the logical counterposition that our species has a woeful record of quickly eradicating just about every large animal encountered in newly discovered lands. This is certainly true of small islands, of which Flores is one. You have only to think of all the Pacific islands visited by intrepid Polynesians (New Zealand, for example), but the same story holds true around the world. If you follow Jared's reasoning, then the hobbit (and the pygmy elephant) would have gone the way of any small animals—exterminated in short order!

And this is the nub of the problem I haven't satisfactorily resolved in my own mind: the overlapping dates for the existence of the hobbit and the widespread dispersal of Homo sapiens throughout Southeast Asia, versus the survival of the pygmy elephant (in particular) until 12,000 years ago. I'm less perplexed about the survival of the little people until a similarly recent time, for the reasons I expressed to Marek—that is, I think the hobbits were fully capable of looking after themselves. But the pygmy elephants? Nowhere else on Earth would they have survived alongside us for 30,000 years or more.

Something doesn't add up, and it'll be fascinating to see how the issue resolves itself in due course. There are two ways in which we could bolster the "coexistence" proposition: find earlier evidence (before 12,000 years ago) for Homo sapiens on Flores or find later evidence (after 11,000 years ago) for Homo floresiensis on the island. So it's back to the field, to search for more clues!

Q: The advanced stone tools found on the Flores site—do they fit a six-foot-tall human or a three-foot-tall human? Jacob D. Miller, St. Charles, Illinois

Roberts: You might think that a three-foot-tall human would have used stone tools only half the size of those used by a six-footer, but this scaling relationship quickly disintegrates if not all the tools are for holding in the hand. As it happens, most of the stone tools recovered from the Liang Bua deposits are not especially large (a few centimeters in size—we illustrated some of them in one of the Nature reports), and certainly not the chunky Acheulian-style hand axes so beloved of filmmakers! The majority were simple flakes, but the archeologists also unearthed microblades that were probably hafted as barbs. They also found other types of stone tools, including points and perforators, which they thought might have been used for hunting "big game" such as pygmy elephants and Komodo dragons.

Thus far, a range of stone tools has been found, from very small (microblades) to very large. The latter refers to a massive chopper that was found amongst the river-lain gravels and cobbles at the back of the cave, and dated to more than 100,000 years old. In such a high-energy river environment, however, any delicate tools would likely have been mashed up and washed away, with only the most sturdy of tools preserved for posterity. And we also don't know who made the earliest tools, as we have no skeletal remains preserved in those deposits. So yet another avenue to explore in the years to come!

Q: How sophisticated were the stone tools that you found? Were they as sophisticated as Neolithic tools of Homo sapiens, or more like those of Homo erectus? Anonymous

Roberts: Team leader Mike Morwood and Ph.D. scholar Mark Moore at the University of New England in Australia have studied these tools closely. The tools found alongside the remains of Homo floresiensis are as sophisticated as anything that modern humans (Homo sapiens) were making at around this time. Indeed, until we found the partial skeleton of Hobbit [as team members dubbed the new species of human], we had thought that the well-made stone tools were the handicraft of modern humans! But we dismissed this notion once we had found the remains of at least eight Homo floresiensis individuals and no modern humans in the cave deposits underlying the 12,000-year-old volcanic ash layer, which sealed their fate, quite literally!

It might seem surprising that Homo floresiensis was making such sophisticated stone tools, given that its brain was only one-third the size of ours! But a recent study published in the journal Science by Dean Falk (Florida State University) and colleagues showed that the frontal part of the Hobbit's brain was extraordinarily highly developed. So, although small, it was fantastically well-wired, and there's no reason now to doubt that these half-size humans could have made the sophisticated stone tools found next to their skeletal remains.

Homo erectus, on the other hand, is usually associated with more crudely made stone tools, but we have no erectus tools at the cave site (Liang Bua) for direct comparison. Even the 840,000-year-old stone tools found earlier by Mike Morwood in the Soa Basin of central Flores (about 60 km east of Liang Bua), that were originally thought to have been made by Homo erectus, may have been made by the ancestors of Hobbit. And although we think that Homo floresiensis evolved from Homo erectus, we simply don't know at the present time (because we have no human remains) if those ancestors were well down to path to being Homo floresiensis 840,000 years ago, or if they were still very erectus-like. There are still plenty of new discoveries waiting to be made!

The Neolithic is a different kettle of fish. There are lots of differences between the deposits containing the remains of Homo floresiensis and the overlying Neolithic deposits. For a start, the Neolithic levels contain many deliberate burials (all of modern humans), with grave goods, whereas we have no indication of deliberate burials for Homo floresiensis. The Neolithic levels also contain pottery as well as evidence of domesticated plants and introduced animals, so a great many changes in lifestyle accompanied the Neolithic. Because of this, much of the research carried out by Indonesian archeologists, at least up until now, has concentrated on the Neolithic. So the Paleolithic has remained very much a closed book, but clearly one worth reading!

Q: I read an article that indicated the size of the people on Flores was due to island effect. I can understand that limited resources would shrink people and elephants. Why would it make small animals like rats larger? If the resouces are limited, aren't they limited for all?

Also, about calling them little people -- they look far more simian than human. Bob

Roberts: I'll start with your last question first. It's difficult to be precise about the physical appearance of Homo floresiensis. We can reliably reconstruct, as in a forensic reconstruction, what the skeleton and muscles might have looked like, but the parts like ears, nose, hair, and eye color leave more to the imagination. Their skin was probably dark in colour, given their sun-bathed, tropical environment, but how crinkled was it? We don't know. Perhaps it's a fair indication of our uncertainty on these finer details that the images created by Peter Schouten (the painting that was widely used by the media in October 2004, when we reported our findings), by Scientific American magazine (cover of their February 2005 issue) and by National Geographic magazine (cover of their April 2005 issue) all differ in several respects. So it's important to look for the similarities (short stature, small skull size and distinctive features, arm length relative to stature, and so on) and realize that it's only these that we can reconstruct with confidence.

The resource question is more complicated than it might appear. Big mammals that require lots of food to exist and reproduce are the major casualties of landing on a small island. There's simply no advantage in being big if it exposes you to a greater likelihood of starvation. Reptiles, on the other hand can afford to get bigger, because their food requirements are much more modest. The Komodo dragon did exactly this and took on the role of top predator on Flores, as there was no competition from large carnivorous mammals. Small mammals can sometimes get larger too, if there is an empty niche to fill. Hence the Flores giant rat, which is about the size of a large rabbit. This turns out to be pretty much the optimum size for a mammal in this kind of environment, according to a comment that was made by the biologist Adrian Lister.

Q: I lived on Maui for 11 years. Hawaiian lore and legends, which constitute an oral history, are full of details about the menehunes, the little people that predated the Hawaiians and are credited with building rock structures throughout the Hawaiian Islands. When I read of the recent "little people" discovery, it seems like evidence of their existence. What do you think about this connection? Anonymous

Roberts: I've had lots of letters and e-mails from people telling about their favorite "small folk" legends and beliefs! There is absolutely no doubt that the tropics in particular were and still are inhabited by a range of pygmy humans. But the key point to bear in mind is that all these pygmies are modern humans, and not another new species of human. They are just small versions of us, although their head size has not shrunken much. By contrast, Homo floresiensis is an entirely new species of human, which differs in a great many ways from us, so the only similarity between other reports of "small folk" and Homo floresiensis is the short stature—there are almost no other points of agreement. Now, if the menehunes had other similarities with Homo floresiensis (head size and features, arm length relative to stature, etc.), then I might get interested.

Intriguingly, there are such legends on the island of Flores itself, of a people they call Ebu Gogo. Some of the anatomical features sound remarkably like those of Homo floresiensis, but there are no skeletal remains of Ebu Gogo for comparison, nor any scientifically documented evidence of the existence of Ebu Gogo, so such legends will just have to stay that way for now!

Q: How many of these creatures were found, and how old are the skeletons? Bob Meyer

Roberts: The original skeleton was unearthed at Liang Bua by Thomas Sutikna, one of our most valued Indonesian collaborators at the Centre for Archeology in Jakarata, in September 2003. We then quickly set about dating these and other nearby deposits, from which the archeologists had also recovered a few fragments of Homo floresiensis material. By the end of the 2004 field season, we had the fragmentary remains of at least eight individuals. Their ages range from around 95,000 years old, from the oldest and deepest part of the cave deposit, to as young as 12,000 years old—just before they were wiped out by the volcanic eruption that deposited a thick ash layer in the cave.

We used four different dating methods. Chris Turney, a colleague here at the University of Wollongong in Australia, used radiocarbon dating to date charcoal fragments found next to the skeleton. Radiocarbon dating is the mainstay of archeological research and is extremely reliable for materials ranging up to a few tens of thousands of years old. Chris obtained a date of 18,000 years for the skeleton. Kira Westaway, a Ph.D. scholar at the University of Wollongong, and I also dated the deposits using luminescence dating techniques, which can be applied to mineral grains of quartz and feldspar. We could bracket the age of the skeleton to between 14,000 and 35,000 years ago, which backed up the radiocarbon age.

We also used luminescence dating methods to obtain the 95,000-year-old date mentioned earlier, while our colleagues Jian-xin Zhao (University of Queensland, Australia) and Jack Rink (McMaster University, Canada) used their expertise in uranium-series dating of flowstone (crystals of calcite that formed in caves from dripping water) and electron-spin resonance dating of tooth enamel (taken from the tooth of a young pygmy stegodon, an extinct type of elephant) to provide dates for other parts of the cave deposit. All in all, the ages obtained from these different methods stacked up extremely well against each other, which provided us with a good deal of confidence in deciding exactly when Homo floresiensis lived and died at Liang Bua.

Q: In view of the fact that we modern humans retain a number of primitive traits, is it possible that erect walking itself is a primitive trait that is in fact very old and was carried down through several lines of exctint apes that are related no closer than we are to say the great apes? Anonymous

Roberts: The history of bipedalism (erect walking) is still very much a hotly debated issue in paleoanthropology. Earlier this month, for example, Nature published a paper that suggested the 7-million-year-old hominid in Chad (the earliest known hominid) was an upright biped, and so bipedalism first arose soon after the human lineage diverged from that of chimps. This claim will remain controversial until more fossils come to light, but it does show that bipedalism has likely been around for a long, long time—possibly as long as the human lineage has been in existence!

Q: The PBS program tonight on television showed Homo floresiensis, which reminded me of the clan or tribe of negritos living (in 1967) on Clark Air Force base in the Philippines. I wonder what happened to them after Mt. Pinatubo exploded? The adults are only about 40 inches tall. They had free medical and other care at the U.S. air base. They did much recon scouting in World War II. Bob Wickman

Roberts: This is another good (and reliable) report of "negritos," a term often associated with tropical pygmies in Southeast Asia. As mentioned above, despite their short stature, they have nothing else in common with Homo floresiensis. They are simply a smaller version of ourselves. If you defleshed them (which I don't recommend you attempt—the Andaman Islanders, another group of pygmy people in Southeast Asia, had fearsome reputations and would have defleshed you!), you'd find that the features of their skeleton were identical to ours, differing only in size. By contrast, if you look at the skull and bones of Homo floresiensis, you'd quickly notice a huge number of large and small differences between them and us. Peter Brown, the paleoanthropologist at the University of New England in Australia who described the original Hobbit find, has conducted a fantastically detailed study of these skeletal remains. Some of the gross differences (which I mention below) can be easily spotted by amateur anthropologists (such as me!), but it takes a trained eye and a thorough knowledge of comparative material of modern humans, Homo erectus, and other hominids to tease out the evolutionary relationships between the Hobbit and all other species of human that have walked the Earth.

Q: What is your opinion about whether there is any chance that the "little people" of Flores might still exist in remote parts of that island or nearby islands? In our rapidly shrinking world, where few pockets of unexplored territory supposedly still exist, I have to admit it sounds unlikely. But wouldn't it be wonderful if they did still survive?! Anonymous

Roberts: It would be absolutely stunning, and I'd dearly love to believe that it could be the case. My heart says yes, but my head says no, because the chances must surely be vanishingly small. What part of Southeast Asia hasn't been explored, or at least visited, by modern humans in the last few hundred years? And what part hasn't been radically altered, directly or indirectly, through our activities? But then again, if the legends of Ebu Gogo have even a grain of truth to them, then another type of human was wandering around central Flores until 250 years ago—only just before the Dutch arrived in this neck of the woods!

It is just less than six months ago that we first reported our findings to the scientific community and to the public at large. Naturally enough, our reports were greeted by many with astonishment verging on disbelief, because the discovery came completely out of left field. So while we are still in this honeymoon period of suspended disbelief, I am reluctant to discount entirely the possibility—no matter how remote!—that Homo floresiensis survives up until the present day in a remote pocket of a remote island in Southeast Asia.

Q: It is my understanding that all of the various cousins of mankind originated in Africa prior to moving out into the rest of the world. Would that also be true of this sort of cousin? Jim Parsons

Roberts: We think that this is certainly the case. The nearest anatomical equivalents to Homo floresiensis are the hominid remains found at Dmanisi, in what is now the Republic of Georgia. These are variously assigned to Homo erectus, Homo ergaster, or Homo georgicus by different specialists, but Homo erectus is the most commonly used tag. The Dmanisi hominids are around 1.8 million years old—100 times as old as the remains of Homo floresiensis at Liang Bua!—and are widely regarded as the first humans to venture out of Africa. Perhaps Homo floresiensis evolved from them, or possibly from an earlier exodus of humans, or maybe a later one.

There are a frustratingly large number of possibilities at the present time—remember, it is only 18 months since we discovered the Hobbit skeleton!—and we can speculate at length and at leisure until we find some intermediate-age fossils in other locations to fill in the enormous gaps in our knowledge of exactly which species gave rise to which other, when and how they did so, and where in the world these turning points occurred.

Certainly, the current consensus is that modern humans evolved in Africa by at least 195,000 years ago and left that continent as Homo sapiens (but we're not sure when). We then replaced all other existing species some time (probably soon) after we encountered them, although the exact mechanism of "replacement" remains a matter of debate, so that all humans alive on the planet today are descended from those modern migrants. The corollary is that no one alive today is descended from any other human lineage, such as Homo neanderthalensis, Homo erectus (those that left Africa earlier, such as the Dmanisi hominids) or Homo floresiensis. All of the latter, extinct species are truly dead branches on the human family tree, more's the pity!

Q: What are the specific bones that suggest this is a potential descendant of Homo erectus, and how do they differ from H. sapiens? Betty Goerke

Roberts: It is difficult to encapsulate in a paragraph or two the exact differences between Homo floresiensis and Homo sapiens, because there are so many. Indeed, the now-classic paper in Nature by Peter Brown (University of New England) and other key members of the discovery team that described the original skeleton is devoted to this exact topic, and it took them seven pages of dense prose! So I shall just point out some of the key distinguishing features, of which the skull and mandible (lower jaw) contain a plethora.

For example, we have high foreheads and an inconspicuous brow ridge, whereas Hobbit's forehead receded far more steeply, and she had thick eyebrow ridges. She also had a much thicker skull case than we do as well as a much smaller brain case (about the size of a chimp's). Her premolar teeth have multiple roots (Homo sapiens typically has just one root), the top surfaces of the premolars differed from ours, she had no chin whatsoever (whereas we do), and other details of the chin also differ in important respects. Also, the inside, rear part of the lower jaw is much more heavily buttressed than in Homo sapiens. The list goes on and on!

Other features of the skeleton also differ from ours: in particular, the shape of the pelvis (more flared in Hobbit than in us), the length of the arms (long, relative to stature, compared to Homo sapiens), and other aspects of the bone morphology. I won't say more on the last of these topics, as the details are contained in a paper that is currently under review in a leading scientific journal, and it is bad scientific practise to discuss findings in a public forum before they are made available for scientific scrutiny!

Many of the features of Homo floresiensis chin and teeth that I mentioned above do, however, occur in Homo erectus as well as australopithecines, which is an extinct line of hominids that lived in Africa between about 4 and 1.5 million years ago, and is a genus that includes the skeleton of "Lucy." So in terms of the likely line of descent of Homo floresiensis, all available evidence points towards a deep ancestry with early hominids in Western Asia (Dmanisi) and Africa, with some similarities with early Homo erectus in nearby Java. But, perhaps surprisingly, the Javan Homo erectus are not the nearest lookalikes to the Hobbit! Explaining why this is the case, and deciphering the course of evolution taken by the ancestors of Homo floresiensis after they had left Africa, is a core element of our ongoing research program in Indonesia, which is being led by Mike Morwood (University of New England) and our Indonesian colleagues in Jakarta and Bandung.

Q: My question is how could the H. floresiensis populations survive the Mt. Toba eruption 75,000 years ago? Thanks in advance. Kerem Goksel, Turkey

Roberts: You'd think that the largest volcanic eruption on Earth in the last few tens (if not hundreds) of millions of years would have eclipsed just about every living thing! But this seems not to be so. Toba is situated near the northern tip of Sumatra and its eruption would certainly have wrought total destruction on the inhabitants in the immediate vicinity, with lesser destruction further afield—not just on humans but on all other animals and plants also.

But there is still a great deal of debate in scientific circles about just how destructive Toba really was, both directly and indirectly, and where the destruction occurred. Volcanic ash from the Toba eruption can be found to the east in the South China Sea, and westwards across India into the Arabian Sea, but no one has so far reported vast accumulations Toba ash to the south and east in Indonesia, which is where the island of Flores is located. So the "hobbits" living there probably survived the global cooling that may have persisted for some years (decades?) after the Toba eruption, just as many other animals and plants around in the world survived the event to continue their lineages to the present day.

Q: What is it exactly that classifies the little people of Flores as a "new species?" Is it a difference in the number of genes, or their not having sex with other humans? Thank you. Burl Cooper, Bloomington, Indiana

Roberts: You have to be "reproductively isolated" to qualify as a new species. This might occur because you're physically or genetically incompatible, or are just not interested in another species' mating display! Or the love of your life may be located on the other side of the world, and you never get to reproduce with that individual even though there is no physical or genetic impediment—this is geographical isolation, which is often the start to speciation.

Certainly, as far as the Flores hobbit is concerned, the skeletal evidence shows that they were very different from modern humans, so it would seem very unlikely indeed that our ancestors and theirs chose to have sex. If we can find the DNA of a hobbit, then that would show whether the two species were genetically compatible. Again, that would seem extremely unlikely, as the hobbits had the run of Flores to themselves for many tens of thousands of years, possibly several hundreds of millennia, so they'd have diverged from us genetically over that long period of time.

Q: We seem to be analyzing the "little people" using current "modern" evolutionary engineering and the current shape of our brain with its accumulated knowledge base thus far. The evidence suggests that the brain of the "little people" was different, with the unlikelihood of disease. Wouldn't one be able to at least speculate the potential of developing, by comparison to our present standards, an extremely high feeling of compassion and benevolence with enough ingenuity to maintain survival, while reducing the ability to develop something that can stand in a way of co-existence such as an "ego?" Evolution does not necessarily mean technological advancements, does it? Perhaps, being "leaf-eaters," couldn't the "little people" have economically co-existed with sapiens? Marek, Victoria, British Columbia, Canada

Roberts: You're absolutely right that the hobbits could have co-existed with ourselves, but probably only if the two species didn't occupy environmental niches that were too similar. We know next to nothing about the existence (or non-existence) of ego in prehistory, and this is particularly difficult to investigate in human cultures that didn't develop personal ornamentation, rock art, or some other manifestation of the introspective human mind.

As you say, there's certainly no reason to think that technological advancement equates with the evolution of human behavior. The Australian archeological record is testimony to exactly this fact: the Aborigines made stone tools in much the same way for many tens of thousands of years, presumably because they did they job required of them, yet they simultaneously produced some of most elaborate art creations in the world as well as the manufacture of beads.

And what would we as a species have done if we clashed with a hobbit? Here I differ with Jared Diamond's take on the outcome. While he argues that we'd have quickly eradicated them, I suspect that they would have proven more than a match for us. Remember, they were the incumbents on Flores, they had been living on the island for many, many millennia and would have known the lay of the land intimately, they had brains that could probably carry out very advanced cognitive functions, and they were slaying (Komodo) dragons and half-ton elephants. Then we, Homo sapiens, land on the shore, unacquainted with the new land or with the habits and capabilities of these half-size hunters. Who would you back in a fight to the death? We can speculate endlessly, and this is something we have yet to find any archeological evidence for: who was eating whom, or did we simply avoid each other?

Q: Do you think that these creatures might still be alive in small numbers somewhere? If so, is there a expedition under way to find them? If they are found to be living, what are the steps that would be taken to protect them from poachers, etc.? Eduardo, North Bergen, New Jersey

Roberts: Yes, indeed. What would we do if we found a hobbit tomorrow? Reporting their existence would almost certainly consign them to extinction (where are our tigers, rhinos, gorillas all heading, despite supposedly "secure" premises?), but so too would concealing your discovery. After all, someone else, with a keener eye to financial security, would doubtless come across them in due course. If you have an easy answer to this dilemma, I'm all ears! Personally, I think you'd have to report it to the authorities for implementation of an immediate, internationally endorsed and funded action plan. Otherwise, hunters and collectors would surely spell their demise as soon as word got out.

At the present time, however, no hobbits have been sighted (and none are likely to be, in all honesty). I know of a few research groups that have expressed interest in looking for any lingering little folk, and I can't imagine it wouldn't make headline news if they were successful!

Q: The NOVA scienceNOW segment compared the height of an average adult human to both an African Pygmy adult and a little person of Flores. Are African Pygmies Homo sapiens? How did they get so small? Dana Mathes, Oakland, California

Roberts: African Pygmies are certainly Homo sapiens. All pygmy people alive today (indeed, all people alive today!) are Homo sapiens. I'm not absolutely certain how the African Pygmies got to be so small (it's not my area of research), but I have a vague recollection that it has something to do with a gene associated with a human growth hormone that doesn't kick in when it should, or it kicks out too early. As we know nothing of the genetic make-up of the hobbits, we can only speculate as to whether they also suffered from such a genetic predisposition or whether their small size is entirely due to the diminished resources available on Flores, which would favor the survival and perpetuation of genes from smaller individuals.

Q: Reference was made to stone tools. How would you characterize these? Formal tools? Utilized flakes? Modified flakes? Brendan Fitzsimons, Santee, California

Roberts: In one of the two papers in the science journal Nature, which accompanied the media reports of the discovery, we gave a preliminary account of the stone tools. From the very earliest archeological deposits in Liang Bua cave (about 95,000 years old) up until the hobbits disappeared about 12,000 years ago, the tools are dominated by simple flakes, struck bifacially (that is, from both sides) from small radial cores and mainly on volcanic rocks and chert (a type of flint). There are also more formal tools found only with remains of pygmy elephant (Stegodon), including points, perforators, blades, and microblades that were probably hafted as barbs. We interpreted these tools as evidence for "big game" hunting by Homo floresiensis. This might seem an outrageous proposition for humans with a brain the size of a chimp's, but the analysis of the hobbit's brain shows that the "little people," although small, were probably smart—smart enough to make these specialized stone tools and carry out the hunting activities we'd credited them with.

Q: Can you clarify how direct the association is between the skeletal remains and the stone tools? Stephanie Fitzsimons, Santee, California

Roberts: Good point to raise. The majority of the stone tools were not found next to the Homo floresiensis skeleton, formally known as LB1; in fact, only 32 tools were found in the immediate vicinity. This perplexed us until we carried out more excavations in 2004 and discovered the reason: LB1 had died in a pool of water, and not on a dry part of the cave floor—so not somewhere that people would have been sitting and making stone tools. By contrast, on the dry parts of cave floor, and at the same level as the skeleton, we found very dense concentrations of stone tools—up to 5,500 per cubic metre! So the paucity of tools right next to LB1 made good sense: we shouldn't expect to find many, because the hobbit died away from the surfaces on which her contemporaries were living.

Q: There is debate today (at least in some circles) regarding a possible Homo erectus genetic contribution to indigenous populations in Australia/Tasmania (citing cranial features such as prominent brow ridges, occipital buns, forehead slope, etc.). First, do you feel this is a possibility? Secondly, do you feel that the discovery of a relatively recent erectus (likely) in Flores contributes to this inquiry? Thank you for your time. Anonymous

Roberts: I don't think anyone seriously thinks indigenous Australians have any Homo erectus genes in them, apart from some members of the paleoanthropological community who espouse the "Multiregional Continuity" theory of modern human evolution. But this school of thought is very much in the minority, and the overwhelming majority of researchers would say that all modern-day Aborigines are Homo sapiens. Certainly, some features have been called "robust," but this is a far cry from placing them in an entirely different species. And, of course, there are no genetic impediments to interbreeding between Aborigines and Europeans.

How do the Flores hobbits feed into this debate, given that they are probably descended from Homo erectus? Realistically, not much. Homo sapiens and Homo floresiensis must have shared a common ancestor at some point in the past (as we are in the same genus), but this point in time is likely to have been two to three million years ago, maybe more, and in the African continent. Since that time, the hobbit and ourselves have led genetically separate lives, so that even if a hobbit were discovered tomorrow, I'd be amazed if our genes were compatible. So there's really no chance that the hobbits had any input to the genetic pool of modern-day Aboriginal Australians.