This is a review of Gregory Forth's book and includes a discussion of the evidence for the extinction of Homo floresiensis and Stegodon on Flores at approximately 70 kyr. This was originally written as an invited review with a copy of the book supplied by the publishers.
Peter Brown 14/10/2022
Between Ape and Human: An Anthropologist on the Trail of a Hidden Hominoid By Gregory Forth, Pegasus, Hardcover, 336 pp., $28.95.
Stories about stories
Gregory Forth, a former Professor of Social Anthropology at the University of Alberta, began his ethnographic field research in Flores in 1984 and over several decades made contributions to our knowledge of the ethnoscience and ethnobiology of southeast Asia. Written for a general audience, Between Ape and Human: An Anthropologist on the Trail of a Hidden Hominoid (Forth, 2022) examines the connection between Lio speaking informant accounts of a mythical bipedal "ape-man", the "lai ho'a", and a tiny human relative, Homo floresiensis (Brown et al., 2004), that was thought to have been extinct for tens of thousands of years. Are they one in the same and was H. floresiensis to be found living in the remote mountain forests of Flores until recently?
A back story
In 2004 the journal Nature announced the discovery of the skeleton, and associated cultural materials, of an extinct human relative, Homo floresiensis (the "Hobbit"), from archaeological excavations at Liang Bua cave in western Flores, Indonesia (Brown et al., 2004; Morwood et al., 2004). Publication of the discoveries from Liang Bua, created both excitement and controversy. Although originally dated to between 95000 and 12000 years ago, the LB1 hominin skeleton combined an ape-sized brain, with extremely small stature, and archaic anatomical features and limb proportions, that were reminiscent of African hominins millions of years old (Brown and Maeda, 2009; Brown et al., 2004). The skeletal remains were also found in association with large numbers of tools made from flaked stone and the bones and teeth of extinct dwarf elephant relative, Stegodon, that may have been hunted by the tiny bipeds (Morwood and Jungers, 2009; Morwood et al., 2004). To almost universal surprise, it appeared that a small brained and apparently primitive hominin had managed to cross several substantial water barriers, in numbers large enough to establish a viable founder population on Flores and was alive at the same time as our own species, Homo sapiens, was in the region (Lahr and Foley, 2004). The comparatively recent survival of a dwarf Stegodon was also unexpected and inconsistent with the evidence for the extinction of this broad taxon from other parts of Asia (Turvey et al., 2013). Based on what was then known about the stratigraphic associations, and dated materials from the cave, it was thought that both H. floresiensis and Stegodon had become extinct on Flores ~12,000 years ago after a massive volcanic event. For palaeoanthropologists, and evolutionary biologists familiar with the hominin fossil record, H. floresiensis, seemed both out of place and out of time. If the skeleton had been found in the east African Rift Valley and dated to 2-3 million years before present, it could have been more easily accommodated within the existing evolutionary framework for our species (Stringer and Andrews, 2011).
The discovery of this tiny primitive hominin aroused the interest of the scientific community and featured on the front page of nearly every major newspaper, and numerous popular science magazines (Mayell, 2004; Wong, 2005). One of the reasons for this is linked to a backstory predating publication and is relevant to the subject of this review. Shortly before publication by Nature in 2004, the journals publicity department contacted the research team asking for agreement on a nickname for the LB1 skeleton. The team could not agree but settled on the "hobbit". I was opposed as Tolkein's creations are essentially just small-bodied Victorian country folk, that live in subterranean houses, have relatively large and hairy feet and go on adventures (Tolkein, 1937). Not difficult to predict that the "hobbit" baggage would create problems of perception and reception. The art departments of many publications fleshed out the LB1 skeleton, with a palette drawn from Planet of the Apes, Tolkein's Middle Earth, and preconceptions of what a primitive human was supposed to look like. This suited some of the research team, and perhaps the publishers, but it also aroused the interest of nearly every cryptozoologist and folklorist on the planet. The Flores "hobbit" was added to their pantheon, as well as the pages of the popular press.
Moving ahead nearly two decades, more detailed archaeological and geochronological research at Liang Bua have modified the initial conclusions about the age of the Homo floresiensis and Stegodon deposits in the cave and the potential contemporaneity with modern humans (Sutikna et al., 2018; Sutikna et al., 2016). The revised stratigraphic and chronological evidence no longer supports the initially inferred ages for the H. floresiensis holotype (LB1), ~18 thousand calibrated radiocarbon years before present (kyr cal. BP), or the time of last appearance of this species (about 17 or 13-11 kyr cal. BP). Instead, the skeletal remains of H. floresiensis and the deposits containing them are dated to between about 100 and 60 kyr ago, with the stone artefacts attributable to this species ranging in age from about 190 to 50 kyr (Sutikna et al., 2016). The simple explanation for why the initial dates from Liang Bua were revised is that a lot more was known about the stratigraphy of the cave deposits in 2015 than in 2003. Cave deposits are usually stratigraphically complex, with flooding, erosion, reworking and redeposition of different parts of the cave floor is common. Objects may move both vertically and horizontally through a deposit due to these processes, as well as treadage, animal burrowing and gravity. These are all issues at Liang Bua. The most reliable guide to whether faunal remains are in the original, undisturbed stratigraphic position, is when skeletal elements are still articulated, or in proximity. This was the situation with the LB1 H. floresiensis skeleton. It is also likely that some of the initial enthusiasm to add human-like cultural baggage, including the use of fire and stone tool cut marks on Stegodon bones, may have been an overreach. Some of the archaeologists and geochronologists believed that the Liang Bua hominins would have greater impact if they were firmly intertwined with the human story, rather than just being recently extinct, tool-making apes. Natural processes can produce scratches on a bones surface, as can the teeth of carnivores and rodents. A detailed analysis of the evidence for the use of fire by H. floresiensis has not been published (2022) and the "cut marks" that I have seen on Stegodon bones (2003-2005) could have resulted from processes other than hominin use of stone tools.
Gregory Forth's stories
During his field work in the Nage region of central Flores in 1984 Gregory Forth overheard stories of "ebu gogo", small, hairy and non-human bipeds that were supposed to have survived until as recently as 200 years ago (Forth, 1998). Hearing reports of how "several generations before, the ancestors of the Nage had exterminated a group of these hairy creatures inhabiting a cave called Lia Ula, located not far above old Ua (Rua) on the northern slope of the volcanoe Ebu Lobo" (12-14). Forth thought that these reports were striking in there "apparent historicity and matter-of-fact quality" which distinguished them from the spiritual and mythical, arguing that the story may have some empirical basis (Forth, 1998, 2005). However, disappointingly, there is no evidence that Forth searched for this cave, and I can't imagine how the total population of this species could have been herded into a cave, on a forested mountainside and exterminated. I suspect that if the legendary Dutch missionary archaeologist, Theodorus Verhoven (Knepper, 2019), had been on the "trail of a hidden hominoid", searching for these caves would have been a priority.
During subsequent ethnographic field work with the Lio community of east central Flores, Forth (2022) heard stories of a creature called "lai ho'a". While the details of the descriptions varied, most often they combined a body height of approximately 91 cm (3'3"), with walking and standing mostly bipedally, more body hair than the Lio, they were rarely seen and then in usually low light and lived in the forested mountains. They were also cultureless, not making or using tools, and known to frequent caves. Importantly, unlike the Nage's "ebu gogo", the "lai ho'a" were possibly still alive. Many cultures have folk-stories about rarely encountered small or large, humanlike creatures, often with magical abilities, and all without verifiable evidence. Forth considered that some of his Lio informants had provided credible accounts and it was possible that this secretive animal may both be a biological reality and still living today, not just another cryptid.
The Lio have no physical remains of a "lai ho'a", although some claim to have had, or have seen, body parts in the past. Gregory Forth makes it clear that he has never seen one of these creatures and the only evidence he was shown, were parts of the skull and skeleton of a long-tailed Macaque monkey. This is not crucial to the success of his investigation, which uses the tools of an ethnographer to decipher the meaning in the stories and language used by informants. He chooses to believe that some stories are reliable descriptions of encounters, some are less reliable, and some details like the occasional presence of a monkey-like tail, should be ignored. For Forth, a reliable story has features consistent with an "ape-man" or "hominoid" (1. see below, Forth does not know what a Hominoid is) living in the natural world and does not contain elements of the supernatural, like the ability to fly or disappear. However, the properties of a natural world, that would provide a behavioural and ecological context for a bipedal "ape-man" the size of a chimpanzee, are never defined. Unfortunate, as this may have produced a more convincing set of arguments.
After introducing H. floresiensis, Gregory Forth provides the initial introduction to his "ape-man" and sets the scene for the rest of his story.
"The other humanlike creature alluded to above, which for convenience I call an "ape-man", has yet to be scientifically identified. But one of several ethnolinguistically distinct groups that populate Flores Island, a people called Lio, claims these creatures are alive (if not well) in remote sections of their mountainous territory. In their own language, the Lio (pronounced "Lee-oh") name these ape-men "lai ho'a". They describe them as small-in fact about the same size as floresiensis-as walking upright on two legs, and as hairy-bodied or, at any rate, hairier than themselves. Lio also characterize the ape-men as cultureless-lacking tools, weapons, clothing, and even fire. Floresiensis, too, might have been hairy, though we shall never know. And while the question has yet to be settled, there's no firm evidence for the fossil species having used either fire or stone tools." (2022: 3)
While the Lio's "lai ho'a", might lack tools and attributes of human-like behaviour, to say that there's "no firm evidence" for H. floresiensis using and making tools is incorrect and contrary to the detailed, peer reviewed literature (Brumm et al., 2006; Moore et al., 2009; Morwood and Jungers, 2009; Morwood et al., 2004; Sutikna et al., 2018). The core and flake stone tools associated with H. floresiensis are found in the layers of the cave deposit dated to 190,000 to 50,000 years, in association with the bones of Stegodons and other extinct fauna. There are no other candidates to have made these tools, it is much too early for H. sapiens (modern humans) to be in the region and too recent for Homo erectus. A failure of comprehension, or is Forth trying to add persuasive force to his future arguments concerning the cultureless "lai ho'a"?
"As for the ape-men, there's reason to believe they could be present-day descendants of floresiensis, and if so it could mean that this species still shares Flores with modern humans... On the other hand, the humanlike creatures Lio speak of could be purely imaginary. Which solution is best supported by the evidence is what this book is all about."(Forth, 2022: 4)
Evidence for the existence of the "lai ho'a" is obtained through conversations with Lio informants. Forth states that he is looking for a coherent image of a natural and hence credible creature. An "ape-man" that could function in the zoological real world. Descriptions of encounters are reported from 112 informants, of which 32 are "eyewitnesses", seven are described as "second hand" accounts and the remaining 73 "who denied any personal experience of the hominoids" (2022: 27). Information was acquired during informal conversation, rather than a formal survey and this may have contributed to the variation in response. Most informants describe a standing height of around a meter, with some estimates 60cm or less. Physical attributes of thin to sturdy, strong, hairier than the Lio, with 11 informants describing them as hairy as a monkey. Faces vary from hairy to hairless, some with short head hair and hair colour in the primate range of reddish to black. Skin colour most often described as black. "All indications are that the head and body proportions are the same as they are in humans" (2022: 33). Hands, teeth, and breasts are most often described as humanlike, and faces as either monkey-like or human-like. Nearly half of the informants reported that the ape-men had tails. As the presence of a tail is inconsistent with being either a human or ape, or any of their fossil ancestors over the last 20 million years (Xia et al., 2021), Forth, devotes a chapter in his book in trying to explain what he sees as an anomaly. Overall, he assesses the informant's descriptions as intermediate between a modern human and non-human primate.
"While I was in the field, one of my Lio hosts once came across a reconstruction of Homo floresiensis in a book I'd brought with me. (This was the well-known painting by Peter Schouten. I didn't deliberately show it to them or anyone else because I didn't want to put ideas in people's heads.) The person identified the picture straightaway as depicting a lai ho'a (ape-man)." (Forth, 2022: 20-21)
This is where the images of H. floresiensis produced for popular science magazines, particularly the "hobbit" portrait by Peter Schouten for National Geographic (Mayell, 2004), can be incredibly misleading (modern human body proportions with a chimpanzee-like face). If your informants identify this image as "lai ho'a", or if you are focusing on a combination of features in your informants descriptions that match popular images, then you are not looking for anything that ever lived in the real world. For instance, when art departments of different publishers were trying to flesh out the bones of the LB1 skeleton in 2004-2005, a lot of attention was paid to the face, particularly the nose and mouth. Broad, flat noses with a chimpanzee-like lip and a face that jutted forward under protruding brows is what they were aiming for. However, the nasal aperture in the actual facial skeleton is small, the front teeth were not large like in apes, without long roots, and did not need the same amount of bony support, so no need for a chimpanzee-like lip or broad nose. The chin was receding and there were slight bony ridges above the eyes, but otherwise an identifiably human-like face (Brown and Maeda, 2009; Brown et al., 2004). If your informants identify "lai ho'a" as having a monkey-like face, then it's unlikely to be a present-day descendant of H. floresiensis. More likely to be a Macaque monkey.
Forth's book proceeds through four sections devoted to different aspects of the ethnographic evidence, with a focus on trying to place his "ape-men" in the real, rather than supernatural world. He believes that the "eyewitness accounts" of Lio informants are truthful stories reflecting their personal experiences. The likelihood that a cultureless, chimpanzee-size primate, would preferentially live in caves in the cooler high-altitude forests, never be seen in social groups, almost always seen singly and in low light, and have a population density too small for survival, are not issues for Forth. He concludes
"So, after considering the alternatives, a living non-sapiens hominin undocumented by science-something like a latter-day floresiensis or another, very similar and presumably related, hominin-appears to be the best explanation for the Lio ape-man. I must confess that this conclusion leaves me uncomfortable, and I have difficulty fully accepting it. The reasons, however, do not concern the evidence so much as ideological and therefore social factors. Among these is probably a lingering influence of the now increasingly challenged but still persisting unilinear view of hominin evolution, bound up with the nineteenth-century notion of "progress", whose most famous proponent was Darwin, and even older ideas about human perfectibility. Another factor is the stigma deriving from a widespread view of people who entertain the possible existence of creatures not (or not yet) accepted by science as mentally peculiar if not downright delusional!" (Forth, 2022: 247-248)
An ancient story
Population density and behavioural characteristics of a living ape, of approximately the same body mass as H. floresiensis, can be used to guide expectations for a similarly sized hominoid on Flores. The most appropriate candidates are chimpanzees, our closest living ape relative. There are two species of Chimpanzee, the bonobo (Pan paniscus) and common chimpanzee (Pan trogolodytes), that can be distinguished by their behaviour, appearance, and genetics (Boesch, Hohmann and Marchant, 2002). The Bonobo is closest in body size (standing height male 119cm, female 111 cm; body weight male 45 kg, female 33 kg) to the estimates for female H. floresiensis (height 109 cm; weight 35.9 kg) and "lai ho'a" (height 100cm; weight no estimate).
Chimpanzees live in a wide range of environments from savanna to woodland and wet forest, at altitudes from sea level to approximately 2000 m. They are omnivorous frugivores, that use tools, and make a wide range of sounds for vocal communication (Nishida, 1990). They have not been recorded in caves and don't use fire. Solitary travel and feeding behaviour are rare and most common when a male is hunting monkeys. When on the ground they usually walk quadrupedally but stand erect in some behavioural displays and they can carry objects bipedally. Chimpanzees live in fission-fusion groups of between 20-120 individuals, at a population density of approximately 0.23 individuals/km2 (Watts, 2012). Home range size can be relatively large but is highly variable at 10-40 km. Average life expectancy and population density are both highest in species-rich and floristically diverse habit without predators. In the wild average lifespan is around 33 years, like what has been recorded for some human hunter gatherers (Wood et al., 2017). A female chimpanzee can expect to give birth to four offspring during her lifetime but less than 50% may survive until 5 years of age (Anderson, 2018; Nishida, 1990).
In the past chimpanzees were distributed in a broad band across equatorial Africa, and while their range is now fragmented, they are still dispersed over >2.5 million km2. A huge contrast with Flores where total land area is only 5,500 km2, of which only 20% is currently covered by broadleaf evergreen forest. If available nutrition on at least 30% of the island was adequate, and if their metabolisms were anything like a chimpanzee (metabolic functions in humans are different to those in apes (Blekhman et al., 2014)), then Flores may have accommodated at least 8000 H. floresiensis, or apes of similar body mass. Why then did Homo floresiensis become extinct 60,000 years ago and what are the implications for the claimed persistence of the Lio's "lai ho'a" into the modern period? Not only the availability of food, but predation, homicide, disease, and accidents have significant influence on wild chimpanzee populations. However, if it was not for the human impacts of deforestation and hunting, particularly recently with rifles, chimpanzee populations would have been stable over a long period. Even with the effects of human activity, the ICUN Red List of endangered species, lists chimpanzees as endangered and decreasing, but with a total population >300,000 (ICUN, 2022).
The only large predator on Flores that has the potential to kill a terrestrial hominoid the size of a chimpanzee, or H. floresiensis, is the Komodo dragon. However, studies have shown that they are not ecological analogues of a typical apex mammalian predator, like a leopard. The preferred prey of large Komodo dragons is introduced Rusa deer (Rusa timorensis) and wild pigs but they have had no impact on the population growth of either species. A low individual metabolic rate, requiring an infrequent and inactive hunting strategy, minimises their impacts on a prey population (Jessop et al., 2020). They were never the threat that popular science magazines would have you believe.
If predator pressure did not have a significant impact on the H. floresiensis population, why are they still not running around in the forests of Flores today? The only other potential source of population decline, leading to extinction, apart from endemic disease and habitat destruction, is the arrival of modern humans on Flores. The story, favoured by some archaeologists has modern humans spreading from the Sunda Shelf, through the lesser Sunda Islands and onto the Sahul Shelf at some time prior to 50,000 years ago (Dennell et al., 2014; Sutikna et al., 2016), potentially eradicating any other hominin species they encountered along the way. However, the earliest skeletal evidence of modern humans on Flores, which comes from Liang Bua cave, only dates to 11,000 years. There are stone tools that they may have made, which have an earlier date, but they are not diagnostic of a particular hominin species.
At Liang Bua, the skeletal remains of H. floresiensis and the deposits containing them are dated to between 100,000 and 60,000 years ago. They are found in association with the bones of pygmy Stegodon (Stegodon florensis insularis), the giant marabou stork (Leptoptilos robustus) and the vulture (Trigonoceps sp.), in deposits stratigraphically beneath a sequence of eight volcanic tephra's (T1-T8) (Meijer et al., 2013; Sutikna et al., 2018; Sutikna et al., 2016). The T1 tephra immediately above the LB1 skeleton has an approximate date of 79 +- 12 kyr. The airborne pyroclastic material that forms the tephra layers must have resulted from massive volcanic eruptions and then either washed, or were blown, into the cave. There was at least one colossal volcanic event in the region, approximately 71,0000 years ago (Scroxton et al.). Earth scientists have found evidence of this in layers within cave speleothems (stalactites, stalagmites, flow stones). Recording traces of volcanic sulphate precipitated into limestone cave systems through dissolution, the authors found evidence of a massive, long term, carbon isotope anomaly, lasting up to 1000 years. They interpret the carbon isotope evidence as indicating that vegetation "may have been wiped out completely", with trees eventually replaced by grasslands (Scroxton et al.). Not a good scenario for browsing Stegodons, large carrion feeding birds and forest dependent hominins.
While it is possible that each of these species may have been present on other large islands in the Indonesian archipelago, the available evidence points to a largescale extinction event on Flores. Homo floresiensis and Stegodon had been absent from Flores for tens of thousands of years before modern humans set foot on the island. While Forth's "ape-men" could have subsequently rafted to Flores from some other island refuge there is no evidence from Holocene age archaeological deposits on Flores, or anywhere else. It also stretches the imagination to seriously consider that the stories of small human-like creatures, told to Gregory Forth by a small number of Nage and Lio informants, are an oral history, or indigenous memory, of an animal that lived 70,000 years ago. After all, humans may only have been on the island for 11,000 years. Of course, if the tales of Nage "ebu gogo" and Lio "lai ho'a" "ape-men" had included mini elephants, the size of cows, that would be an entirely different story.
1. The author tends to use two terms interchangeably, ape-man and hominoid, throughout his book to describe the short, hairy biped in the Lio's stories. For the author, the term "hominoid" means humanlike and describes any creature that looks like a human but is not a human-or at least not a physically modern human. This novel description of a formal taxonomic term is misleading and incorrect. A hominoid is a member of the biological superfamily Hominoidea, including all modern apes and humans, and a number of their extinct ancestors and relatives. The majority would not look at all like a human and would easily be distinguished from them. Perhaps the author was hoping that by using taxonomic terminology that he would be adding a sense of scientific rigour to his argument or making a claim to zoological expertise that he clearly does not have.
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