PALEOANTHROPOLOGY
(see also physiology of Homo sapiens and Homo sapiens genome sequencing projects)

• anthroponomy : the science that deals with the laws of human development in relation to environment and to other organisms.
• sex of fossils : thanks to a similarity between the bones of dinosaurs and birds, by looking at the remains of MOR 1125, a Tyrannosaurus rex unearthed a few years ago in the Montana mountains. By cutting up the dinosaur's skeleton, a substance that looked like medullary bone was found (a tissue that coats the inside of the hollow bones of modern female birds: it is dense and shot through with many blood vessels, which help to transport calcium to a developing egg). The therapods, the group to which T. rex belongs, are thought to be more closely related to birds than to present-day reptiles. Although Tyrannosaurus rex was too cumbersome even to run, it did have hollow bones: the lightweight feature that makes it easier for birds to fly. Finding medullary bone in MOR 1125 implies that the specimen was female. These animals produced their eggs like birds, and probably very differently to crocodiles. Determining the sex of dinosaur specimens is usually tricky. The only way is to find one with eggs in its body cavity, or this medullary material, everything else is just conjecture. Some experts have suggested that females may have more ornamented heads or skeletons that differ from male ones, but such theories have been impossible to prove. Sometimes you might be lucky enough to find a population of dinosaurs that fall into two distinct groups, but even then deciding which is which can be difficult. Although the presence of medullary bone can prove that an animal was female, the absence of such bone does not prove that it was male. It may be that medullary bone is very poorly preserved. Finding it involves cutting the bone in cross-section. There are a lot of bones that museum curators wouldn't want you to cut up. As a female bird ages, her amount of medullary bone dwindles. The thinness of MOR 1125's medullary bone hints that she may have been nearing the end of her egg-laying career : she had probably laid most of her eggs and didn't have many left^ref.

Web resources :
• North Carolina State Museum of Natural Sciences
• Museum of the Rockies
• paleopathology : the study of disease in bodies preserved from ancient times, such as mummies.
• the similarity among structures that arose through independent evolution instead of descent from a common ancestor is termed homoplasy and is a major feature of evolutionary morphology. A fascinating but very difficult question facing evolutionary biologists is whether a complex structure would be less likely than a simple structure to undergo independent homoplastic evolution. On page 910 of this issue, Rich et al.^ref partially answer this question with their analysis of the dentary bone from the lower jaw of an Early Cretaceous fossil monotreme called Teinolophos, an extinct relative of Australia's modern platypus and echidna. The new fossil find offers fresh anatomical evidence to support the hypothesis that a key evolutionary innovation among modern mammals--the separation of the middle ear bones from the mandible--must have evolved independently among the monotreme mammals and the therians (marsupials and placentals). The tiny bones of the middle ear that are used for hearing render modern mammals--including placentals, pouched marsupials, and egg-laying monotremes--unique among vertebrates^ref. The middle ear bones are the malleus, incus, and stapes, and in addition there is the tympanic bone, which supports the tympanic membrane, enabling it to receive sound. The tympanic, malleus, and incus are homologous to bones in the mandible and jaw hinge (the angular, articular, and quadrate, respectively), which are required for feeding in nonmammalian vertebrates^ref. There is also extensive evidence from fossils of extinct cynodont and mammaliaform relatives of modern mammals suggesting that the angular, articular, and quadrate bones in these creatures were used for hearing while still attached to the mandible and jaw hinge^ref. Evolution of the mammalian jaw joint and middle ear represents a classic example of the phylogenetic transformation of a complex functional structure that can be read directly from fossil evidence. However, alternative interpretations have waxed and waned about how these middle ear bones got separated from the mandible during early mammalian evolution. The structure of the middle ear is so complex and unique that some researchers consider the separation of the middle ear bones from the mandible to be the strongest synapomorphic (shared derived) characteristic of living mammals^ref. They also propose that the monotreme, marsupial, and placental lineages split after their common ancestor had acquired this key feature. This view has been contested by others who favor multiple and independent acquisitions of the mammalian middle ear bones after the divergence of monotremes, marsupials, and placentals^ref.


From feeding to hearing. Convergent separation of the middle ear bones from the mandible in the monotreme and therian (marsupial and placental) mammalian lineages. Convergent separation is inferred from the independent loss of the mandibular structures for the attachment of the middle ear bones. Primitive mammalian lineages (gray; blue lines) have a plesiomorphic mandibular trough for full accommodation and attachment of the middle ear bones to the mandible. The internal mandibular ("postdentary") trough is shown in brown. Derived lineages (cream; yellow lines) have lost the mandibular trough and show final separation of the middle ear bones from the mandible. Middle ear bones that are no longer accommodated by the mandibular trough but are still linked by the Meckel's cartilage to the middle of the mandible are indicated by the yellow and blue dashed line^{ref1, ref2, ref3, ref4}. In premammalian cynodonts and such primitive mammaliaforms as Morganucodon (see the figure), the middle ear bones were accommodated within an internal trough in the mandible ^ref. From dental evidence, Teinolophos is unequivocally placed in the monotreme lineage^ref. But like Morganucodon and very much unlike living monotremes, Teinolophos exhibits a well-developed internal mandibular trough, suggesting that the angular (tympanic), the articular (malleus), and other "reptilian" jaw bones remained attached to the mandible through ligaments long after Teinolophos and living monotremes split from the common ancestor of marsupials and placentals. Another recent study shows that the middle ear bones were no longer accommodated by the internal mandibular trough but were still linked via the ossified Meckel's cartilage to the mandible in some triconodont mammals. These mammals evolved after the divergence of the monotreme and therian (marsupial and placental) lineages^ref. The oldest fossil lacking an internal mandibular trough is the Early Jurassic mammaliaform Hadrocodium^ref, which suggests that detachment of the middle ear bones from the mandible occurred among extinct mammaliaforms during the Early Jurassic and before the diversification of modern mammalian clades in the Middle Jurassic^{ref1, ref2}. No matter how complex the modern mammalian middle ear seems to be, when its distribution is mapped onto the latest mammalian family tree, the middle ear bones appear to have evolved at least 3 times. This revelation about the convergent evolution of middle ear bones is certainly exciting enough for most evolutionary morphologists. But even more dramatic is the fact that the new Teinolophos fossil bears an uncanny resemblance to the australosphenidan mammals of Australia and South America^ref. These creatures also possess a very similar internal mandibular trough, indicating that the persisting attachment of the middle ear bones to the mandible is a common feature of both the monotremes and the australosphenidan mammals with tribosphenic molars from Gondwanaland (southern continents) from the Middle Jurassic to the Early Cretaceous, which contrasts sharply with their highly advanced molars. Given current morphological evidence, parsimony predicts the odds in favor of the homoplastic evolution of both the middle ear bones and derived molar features of the australosphenidan mammals (thought by some to include monotremes)^{ref1, ref2}. Recent discoveries of Mesozoic mammals from Gondwanaland, including the toothed monotreme Teinolophos, have already changed our perspective of early mammalian evolution^{ref1, ref2, ref3, ref4}. Teeth and jaws of Teinolophos and its relatives offer a mere hint of how little we know about the diversity of the endemic Mesozoic mammals of Gondwanaland. The new fossil find described by Rich and colleagues sheds light on the great complexity of mammalian genealogical history. It also requires us to accommodate the homoplastic evolution of many complex mammalian cranial and dental structures that would have been unthinkable when we had only the fossil record of Laurasia to consider.

The separation of the middle ear bones from the mandible is considered a defining feature of all modern mammals. Mammals seem to have evolved the delicate bone structure of the middle ear at least twice. The surprising discovery comes from a fossil, found off the southern coast of Australia, that belongs to an ancestor of the platypus. Modern mammals are unique among vertebrates for possessing 3 tiny bones in the middle ear. The malleus, incus and stapes work as part of a chain that transmits sound towards the skull. Birds and reptiles have only 1 bone to perform this function. Because the mammalian arrangement is so complex, scientists believed that the set-up had evolved on just a single occasion, in an ancestor that gave rise to placental animals (including humans), marsupials and monotremes (such as the duck-billed platypus). All this changed when a fossil of Teinolophos trusleri, an ancestor of modern monotremes that lived 115 million years ago, was unearthed. Palaeontologists believe that the middle-ear bones of modern mammals once belonged to the jawbone and later separated to adopt their present location. This is supported by the fact that the middle ear's bones associate with the jaw in the early development of modern mammalian embryos. What makes the Teinolophos specimen surprising is a large groove in its adult jawbone, which indicates that the smaller bones had not yet detached. Teinolophos lived after monotremes split from the placental and marsupial mammalian groups. Its jawbone structure, along with its place in the evolutionary tree, hints that a common ancestor to all these mammals lacked the special 3-bone ear structure. This means that natural selection must have driven the same rearrangement in independent groups, after the monotreme split. The discovery will compel many experts to rethink their appreciation of mammals' common evolutionary heritage. Until now it was considered to be one of the most important shared derived characteristics of modern mammals
• a group of US researchers have petrified wood in record time, compressing a process that normally takes eons into a matter of days. Yongsoon Shin and his colleagues at the Pacific Northwest National Laboratory in Richland, Washington, have developed a technique that converts an average 2-by-4 into a hard, fossil-like sponge in about 5 days. By soaking everyday objects in solutions containing silica, otherwise known as sand, researchers have long been able to make fossils in a matter of months. That may seem counterintuitive, but even natural fossilization must begin within that time frame. The organic material must be stabilized within weeks to months, otherwise it decays. The silica permeates the organic material and hardens early in the process. This creates a structure that survives after the organic material rots away. By creating fossils in the lab, researchers can learn how the process alters organic matter, and where fossils might be found around the world. Shin accelerated the fossilization process by warming things up. He soaked wood in acid for 2 days, and in water and silica for another 2. Then he fired the wood blocks in a furnace at 1,400 °C. The extreme temperatures bonded the silicon in the sand to the carbon in the wood, creating a silicon carbide 'fossil'. Technically, the wood is not really fossilized, because silicon and carbon never bond in normal fossilization, but, fossil or not, the wood makes an excellent sponge. Shin hopes that the wood might someday be used at the nearby Hanford Nuclear Reservation, where underground storage tanks hold some 200 million litres of radioactive material, some of which is boiling from the heat of radioactive decay. If the pores in the wood could be made smaller and more regular, it could be used to sop up the boiling sludge, which is too hot to be handled by conventional clean-up techniques. The wood has other properties that might make it useful. The silicon carbide structure can withstand temperatures of up to 1,500 °C. And it is very tough : 2 diamond blades were broken trying to cut it^ref
• there is no evidence of Neandertal mtDNA contribution to early modern humans^ref
• fire mastering : archaeologists unearthing and sorting sediments at a site called Gesher Benot Ya'aqov in Israel have collected evidence that early humans mastered fire much earlier than previously thought, about 790,000 years ago : burned material made up less than 2% of the total and was concentrated at specific locations in the site, suggesting the fires that created it were started and controlled by early humans. There is already good evidence for hearths that are 250,000 years old, and it was widely believed that the first controlled handling of fire occurred 400,000 to 500,000 years ago. As well as providing protection against wild animals, fire would have enabled hominids to cook their food, stay warm during the winter, possibly improve their weapons, and enrich social lives (people may have gathered around camp-fires, staying awake longer and interacting more than before). This first use of fire correlates with the time that hominids are thought to have entered colder areas such as Europe and Northern China, suggesting that fire helped hominids to explore environments that were previously too hostile. As well as using fire, inhabitants of the site in Israel were collecting plant food, hunting and processing meat. Further analysis of the site's material will determine which species of hominid was responsible for the fires. Homo erectus, Homo ergaster and Homo sapiens were all around at the time, and all were able to walk upright, had large brains and were already using tools made of stone
• flint mining : is a hard, brittle rock that flakes easily to form sharp edges for primitive knives or axes. Tools made from it have been around for some 2.5 million years. But because exposed rock tends to be cracked or weathered, flint from beneath the surface makes superior tools. Beryllium-10, which is produced when cosmic rays that strike the Earth from space react with the silicon dioxide in rock. Tools fashioned from surface flint should have higher levels of beryllium-10 than those mined from underground. Flint blades from Tabun Cave near present-day Haifa in northern Israel have beryllium-10 levels that indicate they were made from mined flint, but tools found in Qesem Cave, barely 100 kilometres to the south, bore the hallmarks of surface rock. Because the tools are the same age, 300,000 years ago, the result shows that early humans living at Tabun were choosier about their raw materials : it indicates a conscious action to recover material rather than just randomly picking it up off the ground. It is not clear what mining methods the Tabun cavemen would have used : they may have had to burrow through > 1 m of sediment, but that does not rule out the possibility that the miners worked with bare hands^ref
• musical instruments : one of the world's oldest known has been discovered by German archaeologists. The 18.7-cm-long flute, which is carved from mammoth ivory, has 3 finger holes and would have been capable of playing relatively complex melodies. The flute was found in 31 pieces in the Geienklösterle cave in mountains near Ulm in southern Germany. 2 other flutes made of swan bones were discovered at the site > 1 decade ago. The 3 are much older than any other musical instrument yet discovered. The deposits where the 3 flutes were found were dated to between 30,000 and 37,000 years old. But it is the extraordinary sophistication of the newly discovered instrument that sets it apart from the swan-bone flutes. Its makers used mammoth ivory, the highest quality material available to them at the time. Carving a flute from solid ivory is much more demanding than making a flute from bird bones, which are already hollow. The crooked mammoth tusk had to be split and the 2 halves carefully hollowed out, then bound and glued together along a perfectly airtight seam. The flute's makers lived in the Upper Palaeolithic era of the last ice age, a period when Europe was occupied simultaneously by the last Neanderthals and the first modern humans. The inhabitants of the region were adept artisans, and small ivory figurines, which are among the earliest known examples of figurative art, have been found in several sites. A few fragments of the Stone Age flute are missing, but to investigate what kind of music the instrument would have made, Friedrich Seeberger, an expert in prehistoric music and co-author of this report, has made a replica in elder wood. The tones are quite harmonic : they don't seem to follow a diatonic scale, but rather the rules of the pentatonic scale that predominates in Asia. A more accurate replica would require the right material: mammoth ivory.


• brewing : throughout history, human societies have used the process of fermentation to create alcoholic drinks. The oldest surviving recipe in the world comes from a 3,800-year-old clay tablet of Sumer, a civilization from the area that is now southern Iraq. Part of a hymn to the goddess of brewing gives details about how to make beer. Oracle inscriptions dating back China's late Shang dynasty (about 1200-1046 BC) also describe alcoholic beverages. Experts believe that fermented drinks probably existed in China and elsewhere much more than 3,000 years ago. But until now they have relied only on the shape and styles of pottery vessels to support this idea. Infrared spectrometry of fragments coming primarily from the bases (which absorb more liquid and collect more precipitates than the container walls) of 9,000-year-old pottery shards from 16 vessels belonging to an early Neolithic village in what is now eastern China showed that the inhabitants of China appreciated a tipple at that time. Chemical residues reveal that the pots were used to hold a drink made with rice, honey and fruit, and are the earliest direct evidence for brewed beverages. The strongest clue was the presence of tartaric acid, the principal organic acid in grape wine, which gives evidence that the drink was fermented. The shards seem to have beeswax residues on them, and grape and hawthorn seeds were also found at the site. The chemical analysis also showed similarities with results from rice wines made today, so the researchers believe that the fermented beverage involved a mix of rice, honey and fruit. The flavour of either hawthorn or grape probably dominated the drink. This is the earliest chemical evidence for fermented beverages that we have from anywhere in the world. As scientists use similar techniques to analyse samples from the Middle East, the production of barley beer there will be found to go back at least as early as developments in China^ref.
• Bolk's retardation theory : the theory that humans, in their development, are at a stage which, in the higher primates, is still a fetal stage.
• pithecoid theory : the theory that man is descended from apelike ancestors.
• Pierolapithecus catalaunicus gen. et sp. nov., a new  ape from Barranc de Can Vila 1 (Barcelona, Spain). , christened in reference to the Catalan village of Els Hostalets de Pierola, where the fossil was found in Spain in 2004, seems to be the most recent common ancestor of gorillas, chimpanzees, orang utans and humans. The ape lived in Middle Miocene (12.5 to 13 million years ago), about the time that our different lineages are thought to have diverged. The specimen consists of 83 bones from an adult male, including parts of the skull, teeth, ribs and fingers. The creature would have weighed about 55 kilograms, making it about the size of a female chimpanzee, but it would have looked more like a primitive gorilla. Intriguingly, the fossil shows a mixture of typical 'apelike' features alongside more primitive 'monkey' characteristics. The creature would have been able to lift itself into a standing position as modern apes can, but its short fingers mean that it would not have been able to grip branches with enough strength to swing from them. This means that tree-swinging might have evolved several times in different apes, rather than being a habit from the start. The earliest great apes might have scuttled around on top of branches, much as today's monkeys do. This fits with the idea that apelike characteristics evolved very gradually, rather than all appearing together in a single ancestor. Complete bones and large bone fragments of the P. catalunicus skeleton.


P. catalaunicus also has a very flat face, with nostrils that are in almost the same plane as its eye sockets. Its face would have looked a lot like a gorilla's does today, but very different from a chimp's, in which the jaw is thrust forwards in a pattern called prognathism. The chimp pattern therefore probably evolved later in the great apes' family history. Although the species was discovered in Spain, it is unlikely to have lived only there. We can speculate and suggest that the probable origin of this animal is Africa, widely agreed to have been the birthplace of modern humans around 160,000 years ago. But palaeontologists also think that Africa's climate, and the number of different species that lived there, would have made it a hotbed of ape evolution for millions of years before that. But the apes could just as easily have been found mainly in Europe, as its climate was certainly different back then. At that time Europe had lots of different apes - you don't necessarily have to invoke Africa as the place where all these things evolved^{ref1, ref2}.
• anthropological genetics : despite the remarkable developments in molecular biology over the past 3 decades, it has had only limited impact on systematics in human evolution. Genetics offers the opportunity to objectively test taxonomies based on morphology and may be used to supplement conventional approaches to hominid systematics. Our analyses, examining chromosomes and 46 estimates of genetic distance, indicate there may have been only around 4 species on the direct line to modern humans and 5 species in total. This contrasts with current taxonomies recognising up to 23 species. The genetic proximity of humans and chimpanzees has been used to suggest these species are congeneric. Our analysis of genetic distances between them is consistent with this proposal. It is time that chimpanzees, living humans and all fossil humans be classified in Homo. The creation of new genera can no longer be a solution to the complexities of fossil morphologies. Published genetic distances between common chimpanzees and bonobos, along with evidence for interbreeding, suggest they should be assigned to a single species. The short distance between humans and chimpanzees also places a strict limit on the number of possible evolutionary 'side branches' that might be recognised on the human lineage. All fossil taxa were genetically very close to each other and likely to have been below congeneric genetic distances seen for many mammals. Periods of around 2 million years are required to produce sufficient genetic distance to represent speciation. Therefore, Neanderthals (Homo sapiens neanderthalensis) and so-called H. erectus were genetically so close to contemporary H. sapiens they were unlikely to have been separate species. Thus, it is likely there was only one species of human (H. sapiens) for most of the last 2 million years. We estimate the divergence time of H. sapiens from 16 genetic distances to be around 1.7 Ma which is consistent with evidence for the earliest migration out of Africa. These findings call into question the mitochondrial "African Eve" hypothesis based on a far more recent origin for H. sapiens and show that humans did not go through a bottleneck in their recent evolutionary history. Given the large offset in evolutionary rates of molecules and morphology seen in human evolution, Homo species are likely to be characterised by high levels of morphological variation and low levels of genetic variability. Thus, molecular data suggest the limits for intraspecific morphological variation used by many palaeoanthropologists have been set too low. The role of phenotypic plasticity has been greatly underestimated in human evolution. We call into question the use of mtDNA for studies of human evolution. This DNA is under strong selection, which violates the assumption of selective neutrality. This issue should be addressed by geneticists, including a reassessment of its use for molecular clocks. There is a need for greater cooperation between palaeoanthropologists and anthropological geneticists to better understand human evolution and to bring palaeoanthropology into the mainstream of evolutionary biology^ref.
• 2 Ethiopian fossils have been crowned as the oldest known members of our species. An estimated 195,000 years old, the pair were witness to the earliest days of Homo sapiens. The discovery adds yet more weight to the argument that Africa, and Ethiopia in particular, was the birthplace of humans. The dating sits well with genetic analyses of modern populations, which suggest that H. sapiens first appeared in Africa around 200,000 years ago. The fossils, called Omo I and Omo II, were found in 1967 at Kibish, near Ethiopia's Omo River, by the famed fossil-hunter Richard Leakey. Although Leakey realized that Omo I, at least, was a H. sapiens, the dating of mollusc shells found with the bones suggested that the specimens were only 130,000 years old. In 1967, dating techniques weren't what they are now and besides, Leakey and his colleagues were more concerned with hunting for something millions of years older. They wanted early hominids; modern humans were like chump change. As a result, nobody attempted to date the fossils' burial site more accurately, despite its significance in helping to settle the debate over humanity's African roots. When modern human origins became a big issue in the early 1980s, Ethiopia was closed. And when the researchers, led by Ian McDougall of the Australian National University in Canberra, attempted to visit Kibish on their latest expedition, it was far from plain sailing : they spent days and weeks waiting just to get a boat to go there. When they finally made it, they collected samples of the rock where the Omo fossils were found. Using an improved dating method based on the rate of decay of radioactive argon, the researchers put the age of rock just below the fossils at 196,000 years^ref. The rock layers were formed in rapid bursts, corresponding to wet periods during which huge amounts of organic matter were dumped in the region by the overflowing River Nile. This means that the fossils are likely to be only slightly younger than the rocks on which they were lying. The age of the Omo fossils provides yet more support for the 'out of Africa' theory, which contends that humankind spent most of its life in Africa, before sweeping across the world during the past 40,000 years. But it is still unclear whether Ethiopia can claim to be the sole crucible of humankind, or whether modern humans arose more widely and gradually across the continent. Archaeological finds from southern Africa suggest that that region may have played an important part in the development of modern human behaviour, which is also part of what defines us as a species. Nevertheless, the dating of the Omo fossils earmarks them as older than a set of ancient human skulls found in Herto, Ethiopia. These were unveiled in 2003 and hailed at the time as the oldest humans. The Herto hominids were christened as a new subspecies, H. sapiens idaltu, meaning 'elder'. Such a move is unnecessary for the Omo specimens : Omo I has always been viewed as thoroughly modern in appearance. And although Omo II, which consists of just a skull with no face, has more primitive features, it is still best assigned to H. sapiens, particularly as both skeletons are now thought to be the same age. There was a lot of diversity at that time : there are no simple linear patterns, so I'd be reluctant to draw a line anywhere. And anyway, if you do that, how many subspecies are you going to end up with?



• Homo floresiensis : 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 1 m tall, had a brain 33% the size of that of modern humans, and lived on an isolated island long after Homo sapiens had migrated through the South Pacific region. 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. The new species was found by Australian and Indonesian scientists in a rock shelter called Liang Bua on the island of Flores^{ref1, ref2}. The team unearthed a near-complete skeleton, thought to be a female, including the skull, jaw and most teeth, along with bones and teeth from at least seven other individuals. In the same site they also found bones from Komodo dragons and an extinct pygmy elephant called Stegodon. The hominin bones were not fossilized, but in a condition the team described as being like "mashed potatoes", a result of their age and the damp conditions. The skeleton had the consistency of wet blotting paper, so a less experienced excavator might have trashed the find. The discovery is prompting increased scrutiny of sites on other Southeast Asian islands, both to look for more of the same species and to place it in context with Homo sapiens and Homo erectus, our closest relative. Homo erectus was found to have lived on the nearby island of Java as long as 1.6 million years ago; the team suggests that the Flores hominins may be their descendants.


Dating more bones could help determine whether the species was a short-lived branch of human evolution or survived for longer. Preliminary dating places it at about 70,000 years ago, but it may extend back 800,000 years. In the meantime, researchers are hoping to find DNA in the bones, which would help to clarify the relationships between species. DNA has previously been extracted from European Neanderthals living in the same time period. But they have so far failed to find DNA in the teeth of the Stegodon found in the same cave. Until around 12,000 years ago, when a volcanic eruption seems to have ended the party, Flores was a looking-glass garden of Komodo dragons and even larger lizards, giant tortoises and enormous rats. Alongside them were tiny, primitive elephants and, as we now know, tiny, primitive people^ref. Probably descended from full-sized Homo erectus that made landfall on Flores as much as 900,000 years ago, the islanders dodged the dragons and hunted the elephants. Killers and quarry became smaller with each generation, instances of the well-known phenomenon of endemic dwarfing in small, inbred island populations, until they were transformed into new species. Homo erectus became Homo floresiensis. These people, each a metre tall as an adult, lived on Flores from at least 38,000 years ago to 18,000 years ago. But fossilization is a chancy business, so it is likely that they were there long before that interval... and long after it. They may have been alive when modern Homo sapiens arrived in the region. Yet as far as we know, Homo floresiensis survived for thousands of years, unnoticed and unmolested by humans, before becoming extinct. The discovery that Homo floresiensis survived until so very recently, in geological terms, makes it more likely that stories of other mythical, human-like creatures such as yetis are founded on grains of truth. The discovery of Homo floresiensis makes it much more likely that stories of other mythical, human-like creatures are founded on grains of truth. In the light of the Flores skeleton, a recent initiative^ref to scour central Sumatra for 'orang pendek' can be viewed in a more serious light. This small, hairy, manlike creature has hitherto been known only from Malay folklore, a debatable strand of hair and a footprint. Now, cryptozoology, the study of such fabulous creatures, can come in from the cold. Another argument in favour of such searches comes from the recent discovery of several new species of large mammal, notably in Southeast Asia. For example, Pseudoryx nghetinhensis^ref, a species of ox from the remote Vu Qiang nature reserve on the border between Vietnam and Laos, was first described from hunting trophies in only 1992. Another species of bovid, the kouprey (Bos sauveli), was discovered in Indochina in 1937. Neither of these creatures is as exotic as a yeti or orang pendek, but the point is made. If animals as large as oxen can remain hidden into an era when we would expect that scientists had rustled every tree and bush in search of new forms of life, there is no reason why the same should not apply to new species of large primate, including members of the human family. The discoverers of Homo floresiensis suggest that their find could be the first of many, and that other species of recently extinct humans might be discovered on other isolated islands. But whether other recently extinct (or extant) hominid species are found or not, the fact that even one distinct species of human was found to have lived alongside modern man not only enriches our understanding of recent human diversity; it could change our view of ourselves in a fundamental way. The discoverers of Homo floresiensis suggest that their find could be the first of many. As far as we know, Homo sapiens is the only species of human that yet lives on the planet. It is very easy to take this solitary estate (and our consequent separateness from the rest of the animal world) for granted, so much has it become ingrained in our philosophy, ethics and religion, even our science. Until very recently, evolutionary thought was couched in terms of a linear, progressive trajectory rising from lower life forms and culminating in man. I have argued elsewhere that this view is not, regrettably, as extinct as it should be^ref. In palaeoanthropology, this idea is seen in the view that only one species of hominid has existed at any one time, each one succeeding the next in a scheme of orderly replacement. This idea began to crumble in the 1970s^ref, since when discoveries of ancient relatives of humans have revealed a marked diversity of form. Human evolution is like a bush, not a ladder^ref. But these discoveries concerned the more remote reaches of human ancestry. Despite the fact that some of our relatives, such as Neanderthal man and Homo erectus, are thought to have become extinct in relatively recent times^ref, our complacency that this view holds for recent history has not been shaken. Until now. If it turns out that the diversity of human beings was always high, remained high until very recently and might not be entirely extinguished, we are entitled to question the security of some of our deepest beliefs. Will the real image of God please stand up? H. floresiensis was part of the Asian dispersals of the descendants of H. ergaster and H. erectus :

The dimensions of the skull and skeleton of H. floresiensis 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). It is closer in size to, but even smaller than, the australopithecines, of which the best known example is Lucy

A handful of critics have questioned the scientific description, contending that the specimens represent a tribe of pygmies, with at least one member having microcephaly. A computer-generated model of the skull of Homo floresiensis, our diminutive human relative, confirms that the controversial specimens from Indonesia do indeed represent a new species. A computerized tomography scan of the H. floresiensis skull was used to create a facsimile cast : then the cast, in particular, the area where the brain fits, was compared with casts from a chimpanzee, H. erectus, a contemporary Homo sapiens and a microcephalic from Europe. Analysis was also done on a number of other specimens, including those of human pygmies. The cast seems to indicate advanced development of the frontal lobes of the brain, where reasoning occurs. Such brain development could be evidence for his theory that the species was able to make or refine stone tools, such as those found with the bones.

Web resources : Flores Special at Nature
• colonization of Americas : traditional theories hold that the first wave of humans to migrate came from Siberia at the end of the last ice age. Skeletons of these migrants are dated at about 9,000 years old. But a 12,700 years old skull from skeletal remain of an individual called Peñon Woman III found in the desert of the Baja California peninsula in Mexico and housed by the National Museum of Anthropology in Mexico City, are long and narrow, completely different to the Native Americans' rounder skull shape. They were embedded in volcanic deposits that deteriorated the structure of the bones and made them difficult to date accurately. The lost tribe of immigrants, known as the Pericues, are related to modern Australian Aborigines, who have a similar skull shape, and that they became extinct between 200 and 300 years ago. There are 18th century reports from missionaries in Baja California of thin, hunter-gatherer, shellfish-eating people. These seafaring travellers would have followed a corridor around the Pacific coast from Australia, along the coast of Japan, to Baja. Researchers think they may have found footprints in southern Mexico that mark the oldest evidence for the presence of humans in the Americas. The impressions, preserved in volcanic ash outside the city of Puebla, have been dated to about 40,000 years ago, beating the oldest accepted evidence of humans in the Americas by some 25,000 years. If proven, the prints would lend support to controversial theories that people reached this land much earlier than previously thought. More work needs to be done to confirm that they have found the mark of human steps. The team first stumbled on the prints in the summer of 2003 while hiking between archaeological sites near the dried bed of Valsequillo Lake. They found an ash field peppered with more than 200 impressions that seem to be footprints from several people, including children, along with birds, cats, dogs and species with cloven feet. They might have been fleeing an eruption from the nearby Cerro Toluquilla volcano. The prints are plainly exposed and in an area that sees traffic in everything from miners who quarry the ash to recreational cyclists. Some worry that human interference, along with heavy rains, might have acted to make the impressions that now look like footprints. Radiocarbon dating was used on shells in sediments just above the layer of ash and found they were about 40,000 years old. The prevailing theory is that people first migrated from northern Asia between 15,000 and 10,000 years ago, crossing to America over a land bridge at the Bering Strait. But controversial genetic analyses of Native American populations indicate that some immigrants may have arrived much earlier than that, up to 40,000 years ago. That predates the ice age that held much of North America in its grip some 20,000 years ago.No direct evidence has been found for this early arrival. The oldest archaeological evidence is found in Chile's Monte Verde ruins, which contains signs of campfires and other clues of human occupation from about 14,500 years ago. Debate continues about what the marks really represent. Human prints are usually so distinctive they are hard to miss. The team plans to excavate the site in the Valsequillo Lake basin early next year, in an attempt to uncover other footprints or signs of human life. In late June 2005, the British Natural Environment Research Council gave the Gonzalez team a US$370,000 grant to continue their work^ref.


Web resources : Center for first Americans
• modern head lice (Pediculus humanus capitis) : today there are 2 distinct genetic lineages, despite the fact that they look almost identical. The 2 louse lineages split around 1.2 million years ago - about the time that the ancestors of Homo erectus were leaving our birthplace, Africa, for pastures new. By the time H. sapiens evolved in Africa about 200,000 years ago we had our own lineage of head lice. Homo sapiens probably picked up the second type of louse about 25,000 years ago as we swept through Asia. That would mean we bumped into our evolutionary cousin Homo erectus after the hominid had lived undisturbed in the East for > 1 million years. Homo sapiens is generally thought to have passed through a tight population genetic "bottleneck" somewhere between 10,000 and 20,000 years ago. One of the louse groups is found on people all over the world and the other is practically exclusive to the Americas : this is consistent with the idea that the latter was acquired relatively recently by a population of H. sapiens, who ultimately found their way across the Bering Strait to colonize North America. One problem is that the most recent H. erectus fossils found in Asia are about 50,000 years old, long before the supposed meeting : but fossil-hunters may yet find much younger ones if they redouble their efforts. The provocative suggestion that modern humans had direct contact with H. erectus rests on the estimated coalescence time for the two lice mtDNA lineages, but coalescence time is largely a function of population size—the bigger the population, the older the most recent common ancestor. This means that if the researchers had used a larger figure for their estimate of the louse population size, they would have arrived at an older date for the point where the two lineages split. If the coalescence time of 1.2 million years for human lice mtDNA reflects either a larger population size for lice or is simply a chance result due to the large variance associated with such estimates, it's possible that human lice have the same evolutionary history as modern humans : in that case, there need never have been transfer of lice from archaic to modern humans. Some hope to answer the question of whether we had sexual contact with H. erectus by studying the genetics of pubic lice (Phthirus pubis). Although these can also be spread when people swap clothes, the main route of transmission is sexual
• More than a century ago, the last great geological period was formally ratified by an international committee. This was the final rocky step in the subdivision of deep time based on the evolutionary progression of animal fossils. However, recent years have seen the identification of an older and tumultuous new interval, the Ediacaran Period, during which Earth's earliest soft-bodied organisms emerged in the oceans. This interval was recently ratified^ref, underscoring advances in the absolute dating^{ref1, ref2, ref3, ref4, ref5} and worldwide correlation of geological strata that were deposited in isolated basins before true animals exploded onto the scene in the succeeding Cambrian Period. On page 95 of this issue, Condon et al.^ref present precise age constraints for the Ediacaran Period. The authors have analyzed volcanic dust in two key depositional layers in the Doushantuo Formation of southern China. Their radiometric dates provide important insights into the rates of geological and evolutionary processes. The first layer, with an age of about 635 million years, is at the base of the new interval, whereas the second, at about 550 million years, may constrain the age of an environmental disaster^{ref1, ref2} that is closely associated with the rapid diversification of the Ediacara biota (see the figure) that lend their name to the new Period.  Early animals? A pile of 3-dimensionally preserved casts of the soft-bodied Ediacaran organism Ernietta from ~545 million-year-old sediments in the Nama Group of southern Namibia. The scale bar corresponds to 15 cm. Convention previously focused on the evolutionary first appearance of a specific fossil or assemblage to define the beginning of new geological periods. In contrast, the beginning of the Ediacaran period is defined by the base of a marine carbonate rock, which formed in southern Australia in the aftermath of a distinctive and potentially global ice age^{ref1, ref2}. Equivalent glacial rocks occur immediately beneath similar carbonates at the base of the Doushantuo Formation. In the area studied by Condon et al., the new ages constrain the Doushantuo Formation, which represents most of the Ediacaran Period, to some 85 million years--a remarkably long interval for only about 100 m of rock. This observation begs the question: How much time may be missing in Ediacaran strata from southern China? In the absence of dates between the two radiometric tie points, one must consider two possibilities: Either the sediments accumulated continuously, albeit slowly (some two orders of magnitude more slowly than in similar environments of the same age), or there are breaks in time (hiatuses or unconformities) hidden within the poorly exposed layers. On the basis of limited physical data, Condon et al. suggest the presence of two such unconformities in their study area near the Yangtze Gorges. The duration of these stratigraphic breaks with respect to the environmental anomaly--reflecting a dramatic change in the cycling of carbon on Earth's surface--and subsequent biological innovations form the cornerstone of their conclusions, and deserve closer examination. Spectacular fossil animal embryos^{ref1, ref2} of great evolutionary importance are found at Weng'an (some 375 km to the southwest of the authors' study area), where the Doushantuo Formation accumulated closer to the shoreline and records only a single surface of unconformity. In such nearshore environments, oceanic sediments are often exposed above sea level, resulting in the removal of underlying sediments and hence the erasure of some fraction of geological time. Which of the two hiatal surfaces from the deeper-water sections at the Yangtze Gorges correlates to the single unconformity at Weng'an? The data are more equivocal than presented by Condon et al., and the choice carries important evolutionary consequences. At the Yangtze Gorges, the extraordinary carbon cycle anomaly recorded in marine carbonates near the top of the Doushanto Formation is truncated by the uppermost unconformity. Condon et al. suggest that there is little time missing across the surface, thereby preserving a causal relation between the environmental perturbation and the rapid diversification of Ediacara organisms and associated faunas around 550 million years ago. However, correlation of this surface and the intervening sediments back to Weng'an tells another story. At Weng'an, both the carbon cycle anomaly and the sediments typical of the uppermost Doushantuo Formation at the Yangtze Gorges are missing, implying a substantial hiatus. Comparison of broadly equivalent strata in southern Australia and the western United States suggests a stratigraphic architecture similar to that in southern China, where similar carbon cycle anomalies are truncated by unconformities. In the western United States, the post-anomaly unconformity removes a minimum of 130 m of section, more than the entire thickness of the Doushantuo Formation. These observations suggest that the unconformity separating the Ediacaran faunas and the carbon cycle anomaly in southern China may, in fact, hide a lot of time, thereby decoupling the environmental and biological events that the authors wish to connect. This is not meant to detract from the important radiometric calibration that Condon et al. provide, but rather to note that the stratigraphic relations between these dates, and therefore their connection to evolutionary events, are far from straightforward. According to Condon et al., the rapid diversification of complex multicellular organisms in Ediacaran oceans forced the carbon cycle anomaly seen worldwide, but this seems possible only if there is no real time missing across the upper Doushantuo unconformity. If this is not the case, then this interpretation may be placing the cart before the horse. Alternative models suggest that environmental changes may have driven evolutionary transformations. In particular, atmospheric oxygen--long believed to be an external forcing factor to evolution--appears to have built up rapidly during the Ediacaran Period, not because of a discrete biological event but as a result of the tectonic forces that lift and erode mountain ranges. Through precise radiometric clocks and clever stratigraphic connections, geoscientists can increasingly correlate Ediacaran sediments that are separated widely in space and time. These tools allow us to piece together a complex puzzle of unforgettable biological events against a background of repetitive climatic and environmental perturbations. However, even with exact dates, the cyclicity of these events and the specter of a fragmentary rock record add uncertainty to our picture of Ediacaran Earth history.
• The virtual reconstruction of a skull unearthed at the base of the Saharan dunes in northern Chad may dispel controversy over whether its owner was human or ape, says a team of palaeoanthropologists. The skull, nicknamed Toumaï, along with teeth and a lower jaw was excavated by a team led by Michel Brunet of the University of Poitiers, France. The find was unveiled in 2002 and dated to about 7 million years ago. Based on the size and shape of the teeth and skull base, Brunet's team assigned Toumaï to a new species, Sahelanthropus tchadensis, the 'man of Chad'. Some anthropologists disagreed with the researchers' claim that S. tchadensis is the oldest known member of the hominid lineage, making it more closely related to us than to other apes. They argued that the features Brunet and colleagues were calling human-like, especially parts of the skull, were actually more gorilla-like. However, new teeth and jaw specimens from the Toros-Menalla site in Chad and a digital representation of Toumaï's head^{ref1, ref2} build on the original findings. Now it's completely confirmed that Toumaï is not a chimp, or a gorilla, but a true hominid. The new teeth samples verify that Toumaï had small canines, alongside large molars and premolars that had thick enamel. Such a pattern is similar to that of later members of the human family. The virtual reconstruction uses a high-resolution CT scan to show what the fossil would look like without its cracks and other distortions. The reconstruction shows that the opening in the base of the skull through which the spinal cord passes, called the foramen magnum, is oriented so that the neck points downwards. But in apes, such as gorillas, the neck point backwards. This means that Toumaï's head balanced on top of its spine, suggesting an upright walking stance. The evidence certainly suggests that Toumaï was a biped. However, some believe that although Toumaï is related to the common ancestor of humans and chimps, it is not a hominid. Based on the reconstruction, he believes the site on the back of the skull where the neck muscles attach would support huge muscles, similar to those of apes. This doesn't fit in the functional range of bipedalism. All of the earliest known bipeds, such as the hominid Australopithecus afarensis, which is about half as old as Toumaï, had large neck muscles. This work confirms that Toumaï is the earliest and most complete hominid, and suggests that the earliest hominids were bipedal


• The first modern humans to emigrate from Africa may have done so by sticking to the coast. Analysis of surviving aboriginal populations in Southeast Asia suggest that they arose from a single wave of migrants who left the Horn of Africa more than 65,000 years ago. By following the coasts, say the authors of the new analyses, early humans may have been able to colonize the globe with remarkable speed - reaching far-flung lands such as Australia within just a few thousand years. Most experts agree that modern humans arose in Africa before spreading throughout the world. But while archaeological evidence suggests that humans moved north into Egypt and the Middle East, climate records show that this region was an inhospitable desert until 50,000 years ago, making this an unlikely choice of route. Journeying east around the coastlines of Somalia and eventually India would have been one alternative. It wouldn't have been difficult to live on the coast : in fact, it would have been quite appealing. Macaulay and his colleagues tested this idea by studying DNA from the Orang Asli people in Malaysia, who are not thought to have interbred with other groups. We're interested in working out who the first people to move out of Africa were, so the obvious people to sample are indigenous ones. The researchers collected cheek cheek-swab samples from 260 Orang Asli tribespeople, and analysed their mitochondrial DNA, which is passed down unaltered from mother to child. They then compared this with mitochondrial DNA from other populations - the difference between them reflects the time since the groups diverged^ref. Another research group, led by Lalji Singh of the Centre for Cellular and Molecular Biology in Hyderabad, India, carried out similar tests on indigenous people living on the Andaman Islands in the Indian Ocean. By comparing these with data on mitochondrial DNA from other populations in the region, the researchers conclude that the 2 populations are descended from a single group of people, containing perhaps 600 females of reproductive age, who lived in India around 65,000 years ago. If the Andaman and Orang Asli people could not have travelled by a circuitous inland route, and they could not have stayed so closely related to the original Indian population^ref. If humans tended to migrate along coasts, it might explain how they moved so quickly. The earliest human remains found in Australasia are some 60,000 years old, which means the early pioneers must have averaged several kilometres a year. Being confined to coastlines, where there is limited space to expandd is limited, might have meant that settlers used up their resources more quickly and were then forced to move on. What's more, if sea levels have risen since then, many archaeological remains may now be under the sea floor, potentially explainingwhich could why most remains have been found inland. The fact that these tribes are related to a single small population suggests that humans only emigrated from Africa only once, but mitochondrial DNA does not provide very accurate timing, because it is smaller than the overall human genome and so is therefore more susceptible to mutational quirks. I'm not yet convinced that there was one small, rapid exit - I'm not sure that's the whole story, but the coastal route is plausible. Macaulay and his team now plan to sample more populations from India and Arabia, and to look at other genetic markers besides mitochondrial DNA, to add more weight to the theory^ref.
• A monkey species was discovered in 2004 in Tanzania by 2 groups of wildlife biologists almost simultaneously on mountain ranges some 370 km apart. The researchers classified the animal as Lophocebus kipunji and gave it the common name 'highland mangabey'. These medium-sized monkeys dwell in trees and have a black face with long whiskers. But what caught the scientists most off guard was the distinctive noise that they make. The two highland mangabey populations are separated by dry bush. Because the monkeys can only move and thrive in forest environments, this is evidence that forest probably connected the two mountain areas in the past. At some point the populations had a common ancestor in one site. But the mangabeys are already threatened. Land development threatens the small remaining forest where highland mangabeys can survive. < 1,000 of these monkeys exist and the species should be classified as critically endangered. Habitat loss is probably the major contributing factor. The chances of finding other, undiscovered populations of highland mangabeys are slim. Most of the mountain forest of southern Tanzania has already been surveyed. Because there are so few highland mangabeys left, the researchers have chosen not to capture any of them. But they do hope to obtain DNA samples in the wild to analyse how closely related the animals are to other mangabey species. More monkey species may yet be discovered : the find indicates that there is a lot that we don't know even about comparatively large mammals. There are already about 90 species of monkey known in Africa, the last discovery being the sun-tailed monkey, Cercopithecus solatus, found in Gabon in 1984^ref.


• Archaeologists have entered a long-sealed crypt in Guatemala to find an ancient murder scene. The tomb, in the ancient city of Waká, contains the remains of 2 women, one pregnant, arranged in a ritual tableau. The young, wealthy women were probably slaughtered as part of a power struggle between Mayan cities. And that sheds new light on the role of women in the Mayan culture 1,600 years ago. This tomb tells us that women were extremely powerful : when there were political disagreements, women were killed. Waká, also known as El Perú, lies by the San Pedro River about 60 km west of the more famous site of Tikal. Once thought to be a minor player in the Maya world, Waká has recently emerged as a key pawn in the bitter rivalry between the cities of Calakmul, to the north, and Tikal. Women probably played an important role in those battles : when one Maya group conquered another, it may not have been enough to simply invade and take over. It may also have been standard practice to slay women of the elite class. The usurpation of power may have required the ritual and public extinction of the immediate family line. Excavations at other Maya tombs had hinted at the bloodiness of such takeovers, but the findings at Waká are some of the best documented and most detailed yet. Waká reached its height between AD 400 and 800; the newfound tomb dates to the beginning of that reign, between about AD 350 and 400. It is at least 2 centuries older than a queen's tomb found at Waká in 2004. The tomb was uncovered in late April while excavating one of 3 pyramids atop Waká's highest hill. Inside the tomb, both women had been carefully arranged. The pregnant one was laid face down with the other woman on top, face up. Both had shells and ear decorations arranged by their skulls. Stingray spines had been placed near their groins, a possible sign that they were regarded on the same level as warriors. Their deaths would have made a powerful political statement. The tomb also contained a handful of elaborately painted ceramic vessels, comparable the pots to the Mayan equivalent of delftware. The artefacts and bones have been moved to the project's laboratory in Guatemala City, where they can be studied further^ref.
• the famous catacombs of ancient Rome are huge underground cemeteries, of which 2 Jewish catacomb complexes of uncertain age and 60 early-Christian catacombs have survived. Radiocarbon dating has been used to determine the age of wood originating from one of the Jewish catacombs and find that it pre-dates its Christian counterparts by at least 100 years. These results indicate that burial in Roman catacombs may not have begun as a strictly Christian practice, as is commonly believed, but rather that its origin may lie in Jewish funerary customs^ref.
• There occurred violent earthquakes and floods. And in a single day and night of misfortune... the island of Atlantis disappeared in the depths of the sea. This account, written by Plato more than 2,300 years ago, set scientists on the trail of the lost city of Atlantis. Did it ever exist? And if so, where was it located, and when did it disappear? One candidate for the lost city is the submerged island of Spartel, west of the Straits of Gibraltar. The top of this isle lies some 60 m beneath the surface in the Gulf of Cadiz, having plunged beneath the waves at the end of the most recent ice age as melting glaciers caused the sea level to rise. Geological evidence has shown that a large earthquake and a tsunami hit this island some 12,000 years ago, at roughly the location and time indicated in Plato's writings. Gutscher has surveyed this island in detail, using sound waves reflected off the sea floor to map its contours^ref. His results bring mixed news to Atlantis hunters. At first, his conclusions seemed disappointing. At the time identified by Plato for the city's loss, the sea level would have been fairly high on the island's banks. According to sea-level measurements alone, the island would have been reduced to wave-swept rocky islets and would have been < 500 m in diameter, making it impossibly small for a sophisticated city. But there is a saving grace. The island might have sunk further since those times from seismic activity. Layers of turbidite, the sand and mud shaken up by underwater avalanches, suggest that eight earthquakes have happened in the area since Atlantis sank. Each earthquake could have resulted in a drop of the sea floor by several metres. So 12,000 years ago, Spartel might have been 40 metres higher than expected, and could have measured five by two kilometres. This does not mean the island was inhabited. At a conference of Atlantis researchers in Greece in July 2005, he became convinced that the sophisticated city described by some could not have existed this long ago. "If inhabited, it would have probably been simple fishermen and not a Bronze Age culture as described by Plato. The Bronze Age is usually described as beginning just 5,000 years ago. This reflection data revealed no unusual geometric structures that could suggest an extinct civilization. The Egyptians who told Plato the Atlantis story may have used a different definition of 'years', meaning the destruction of Atlantis happened more recently than thought. The conference in Greece came to no firm conclusions about the city's existence. But researchers managed to agree on 24 criteria that a geographical area must satisfy in order to qualify as a site where Atlantis could have existed. The place must have accommodated such oddities as hot springs, northerly winds, elephants, enough people for an army of 10,000 chariots, and a ritual of bull sacrifice. At present there are half a dozen candidates for Atlantis's location, each one with its own shortcomings. Some say that settling on a final answer may prove impossible. The geophysics is well done, the geology excellent, but most of Plato's description of Atlantis is so ambiguous and open to interpretation. With the information we have from the ancient text, it may never be found, if indeed it ever existed.
• scientists have picked apart some 500-year-old calculations from the Inca empire. The team deciphered the maths from a series of 'khipus': elaborate structures of coloured, knotted strings. Researchers have long known that the Inca, who lived along the west coast of South America from AD 1400-1532, used such cords to record numbers. But this is the first mathematical relationship found between khipu. And that may help to work out what kind of information they stored. Khipus encode numbers as knots in strings hanging from a cord. The closer a knot is to the cord, the higher its value, just as the number 1 can denote 1, 10, or 100 depending on its position. Numerical value also depends on a knot's shape. Single overhand knots encode tens, hundreds or thousands. Single knots represent ones, and long knots with between 2 and 9 turns encode the numbers 2 to 9. The challenging thing is that, while we can read these numerical values that are knotted onto the strings, we don't know what they refer to. 21st century computer power was used to seek numerical relationships between different clumps of string. They analysed a group of 21 khipus found all together in 1956, near an Inca palace at the archaeological site of Paruchuco, in the Peruvian capital Lima. These are the only khipus found so close to each other, Urton says, making it more likely that at least some of them served similar purposes. Sure enough, seven of the khipu were numerically related. The summed values of all strings of the same colour of one khipu, for example, matched the sums on the corresponding strings of another khipu. The sums of that khipu, in turn, could be found on the corresponding strings of a third khipu. The numbers didn't add up perfectly, but this may be because the Inca rounded numbers up or down, or took averages of their results. These sums might record tax payments. Incans paid their taxes by working a certain number of days per year on state projects. The knotted strings could represent such days, and the sums could represent totals for all work in a certain area. Others think the numbers are probably records of animal sacrifices. Sacrifices were very important to the Incas : if they didn't make the proper sacrifices, it wouldn't rain. The team has created a database of the numbers, colours and other features of 290 khipus - about half of the 600 found so far. They hope to mine this in search of further patterns^ref.

Web resources : The Khipu Database Project
• North America lost most of its large vertebrate species — its megafauna — some 13,000 years ago at the end of the Pleistocene. And now Africa's large mammals are dying, stranded on a continent where wars are waging over scarce resources. However much we would wish otherwise, humans will continue to cause extinctions, change ecosystems and alter the course of evolution. Here, we outline a bold plan for preserving some of our global megafaunal heritage — one that aims to restore some of the evolutionary and ecological potential that was lost 13,000 years ago, and which offers an alternative vision for twenty-first century conservation biology. Our vision begins immediately, spans the coming century, and is justified on ecological, evolutionary, economic, aesthetic and ethical grounds. The idea is to actively promote the restoration of large wild vertebrates into North America in preference to the 'pests and weeds' (rats and dandelions) that will otherwise come to dominate the landscape. This 'Pleistocene re-wilding' would be achieved through a series of carefully managed ecosystem manipulations using closely related species as proxies for extinct large vertebrates, and would change the underlying premise of conservation biology from managing extinction to actively restoring natural processes. Historic vision. Our proposal is based on several observations. First, Earth is nowhere pristine; our economics, politics, demographics and technology pervade every ecosystem. Such human influences are unprecedented and show alarming signs of worsening. Second, environmentalists are easily caricatured as purveyors of doom and gloom, to the detriment of conservation. Third, although human land-use patterns are dynamic and uncertain, in some areas, such as parts of the Great Plains in the USA, human populations are declining — which may offer future conservation opportunities. Fourth, humans were probably at least partly responsible for the Late Pleistocene extinctions in North America, and our subsequent activities have curtailed the evolutionary potential of most remaining large vertebrates. We therefore bear an ethical responsibility to redress these problems. North American conservationists routinely turn to the arrival of Columbus in 1492 as a restoration benchmark. But the arrival of the first Americans from Eurasia roughly 13,000 years ago constitutes a less arbitrary baseline. Mammal body-size distributions were similar across all continents before the Late Pleistocene, but subsequent extinction of most large species drastically altered those distributions in favour of smaller species. In the Americas, where large-vertebrate losses were greatest, the subsequent changes were undoubtedly ecologically and evolutionarily significant. Large carnivores and herbivores often play important roles in the maintenance of biodiversity, and thus many extinct mammals must have shaped the evolution of the species we know today. For example, the pronghorn (Antilocapra americana) evolved over four million years in North American grasslands that changed abruptly in the Late Pleistocene; the now-extinct American cheetah (Acinonyx trumani), a key predator, almost certainly shaped the pronghorn's astonishing speed. Beasts of old. Although historical perspectives have influenced modern conservation planning, existing programmes do not adequately address the evolutionary potential and long-term processes involved in restoring large-mammal diversity. Africa and parts of Asia are now the only places where megafauna are relatively intact, and the loss of many of these species within this century seems likely. Given this risk of further extinction, re-wilding of North American sites carries global conservation implications. Moreover, humans have emotional relationships with large vertebrates that reflect our own Pleistocene heritage. > 1.5 million people annually visit San Diego's Wild Animal Park to catch a glimpse of large mammals — more than the number of visitors to most US National Parks. So an understanding of ecological and evolutionary history, inspired by visits to private or public reserves containing free-roaming megafauna, could strengthen support for conservation. Pleistocene re-wilding would probably increase the appeal and economic value of both private and public reserves, as evidenced by the restoration of wolves to Yellowstone National Park. We foresee several phases to Pleistocene rewilding, some of which are already under way. The 50-kg Bolson tortoise (Gopherus flavomarginatus) was widely distributed across the Chihuahuan desert until the Late Pleistocene. Today it survives only in a small part of northern Mexico and is critically endangered. A number of appropriate sites exist for reintroduction, including Big Bend National Park, Texas. And repatriation of captive Bolson tortoises to a private ranch in New Mexico is currently under study. Restoring North America's largest surviving temperate terrestrial reptile to its prehistoric range could bring ecological, evolutionary, economic and cultural benefits, with no apparent costs.

Pleistocene re-wilding in North America.

Symbols represent horses (Equus caballus and E. asinus in black; E. przewalskii and E. hemionus in grey), Bolson tortoises, camelids, cheetahs, Asian (grey) and African (black) elephants, and lions. a, The likely timescale and area required to restore proxies for extinct large vertebrates. b, Conservation value and ecological role (interactivity with other species) on the landscape. c, Potential economic/cultural value versus potential conflict.
Likewise, horses and camels originated in North America, and many species were present in the Late Pleistocene. Feral horses (Equus caballus) and asses (E. asinus), widely viewed as pests in the United States, are plausible proxies for extinct American species. Also, given that most of the surviving Eurasian and African species are now critically endangered, establishing Asian asses (E. hemionus) and Przewalski's horse (E. przewalskii) in North America might help prevent the extinction of these endangered species and would restore equid species to their evolutionary homeland. Similarly, Bactrian camels (Camelus bactrianus) in North America could provide a modern proxy for Camelops, a late Pleistocene camelid. Wild Bactrian camels are on the verge of extinction, currently restricted to the Gobi desert. Domesticated or captive camels might benefit arid North American ecosystems by browsing on woody plants that today often dominate southwestern US landscapes. With proper management, camels could provide economic benefits as well. The overall benefits and disadvantages of horses and camels as proxies will depend on local contexts, and possibly on the presence of appropriate predators. The second, more controversial phase of Pleistocene re-wilding could also begin immediately, with the maintenance of small numbers of African cheetahs (Acinonyx jubatus), Asian (Elephas maximus) and African (Loxodonta africana) elephants, and lions (Panthera leo) on private property. Many of these animals are already in captivity in the United States, and the primary challenge will be to provide them with naturalistic settings, including large protected areas of appropriate habitat and, in the case of carnivores, live prey. The African cheetah, a close relative of the American cheetah, has only a modest chance of persisting in the wild in the next century. Breeding programmes are not self-sustaining, but some of the 1,000 captive animals could be used in re-wilding. Free-roaming, managed cheetahs in the southwestern USA could save the fastest carnivore from extinction, restore what must have been strong interactions with pronghorn, and facilitate ecotourism as an economic alternative for ranchers. Managed elephant populations could similarly benefit ranchers through grassland maintenance and ecotourism. 5 species of proboscidians (mammoths, mastadons and gomphotheres) once roamed North America in the Late Pleistocene; today many of the remaining African and Asian elephants are in grave danger. Elephants inhibit woodland regeneration and promote grasslands, as Pleistocene proboscidians probably once did. With appropriate resources, captive US stock and some of the 16,000 domesticated elephants in Asia could be introduced to North America, where they might suppress the woody plants that threaten western grasslands. Fencing, which can be effective in reducing human?elephant conflict in Africa, would be the main economic cost. Lions, which play a pivotal ecological role in the Serengeti, represent the ultimate in Pleistocene re-wilding for North America. They are increasingly threatened, with populations in Asia and some parts of Africa critically endangered. Replacing the extinct American lion (Panthera leo atrox), although challenging, has clear aesthetic and economic benefits. Among the objections to Pleistocene re-wilding is that the proposed proxies are not genetically identical to the animals that formerly existed in North America. And our vision might strike some as 'playing God'. Existing lions and cheetahs are somewhat smaller than their extinct counterparts, for example, and Camelus is different from Camelops. 'Same' is relative, however, as illustrated by the highly successful reintroduction of peregrine falcons (Falco peregrinus) in North America. Captive-bred birds from seven subspecies on four continents were used, yet there were no differences among the birds in subsequent breeding success, and the subspecies now serve as a collective proxy for the extinct midwestern peregrine falcon. More challenging objections to Pleistocene re-wilding include the possibility of disease transmission, the fact that habitats have not remained static over millennia, and the likelihood of unexpected ecological and social consequences of reintroductions. These issues must be addressed by sound research, prescient management plans and unbiased public discourse on a case-by-case and locality-by-locality basis. Well-designed, hypothesis-driven experiments will be needed to assess the impacts of potential introductions before releases take place. Large tracts of private land probably hold the best immediate potential for such studies, with the fossil record and research providing guideposts and safeguards. For example, 77,000 large mammals (most of them Asian and African ungulates, but also cheetahs, camels and kangaroos) roam free on Texas ranches, although their significance for conservation remains largely unevaluated. The third stage in our vision for Pleistocene re-wilding would entail one or more 'ecological history parks', covering vast areas of economically depressed parts of the Great Plains. As is the case today in Africa, perimeter fencing would limit the movements of otherwise freeliving ungulates, elephants and large carnivores, while surrounding towns would benefit economically from management and tourismrelated jobs. A system of similar reserves across several continents offers the best hope for longterm survival of large mammals. In the coming century, by default or design, we will constrain the breadth and future evolutionary complexity of life on Earth. The default scenario will surely include ever more pest-and-weed dominated landscapes, the extinction of most, if not all, large vertebrates, and a continuing struggle to slow the loss of biodiversity. Pleistocene re-wilding is an optimistic alternative. We ask of those who find the objections compelling, are you content with the negative slant of current conservation philosophy? Will you settle for an American wilderness emptier than it was just 100 centuries ago? Will you risk the extinction of the world's megafauna should economic, political and climate change prove catastrophic for those populations remaining in Asia and Africa? The obstacles are substantial and the risks are not trivial, but we can no longer accept a hands-off approach to wilderness preservation. Instead, we want to reinvigorate wild places, as widely and rapidly as is prudently possible.
• When it comes to working out the relationships between ancient languages, grammar is more enlightening than vocabulary. There are some 300 language families in the world today. Researchers have long studied similarities between the words in different languages to try to work out how they are related. But the rate of change in languages means that this method really only works back to 10,000 years ago. Homo sapiens evolved more than a hundred thousand years ago and by 10,000 years ago had already settled around the globe. So researchers are keen to peer further back in time to see how language evolved and spread. Radiocarbon dating shows humans lived > 35,000 years ago in Melanesia, a group of islands including Papua New Guinea. But the 23 languages that have evolved in this area share few, if any, common words. So the standard techniques cannot reveal much about the languages' histories. The researchers made a database of 125 grammatical features in 15 Papuan languages. This included how word types, such as nouns and verbs, are ordered in a sentence, and whether nouns have a gender, as they do in languages such as German and French. As a test case, the team did the same for 16 Austronesian languages - the languages of the Philippines, Indonesia and Southeast Asia - for which vocabulary analysis has already revealed evolutionary roots. A computer program then analysed the data to determine ancestral language links. This produced up to 10,000 possible family trees and a 'consensus tree' that best fitted the data. The consensus tree for the Austronesian languages closely fitted the accepted lineage from previous study of vocabulary, which demonstrated the validity of the method. The consensus tree for the Papuan languages then revealed previously unknown relationships between those languages. The people of the Solomon Islands and Bougainville Island, for example, seem to be related in language. Perhaps these people were living in one community on a common land mass > 10,000 years ago. The tree will need further work before it can be validated, the researchers say. The team's next step is to apply this method to old languages in the Amazon^ref.

Web resources : World Atlas of Language Structures
• The invention of spears, paradoxically, heralded a long era of peace for Stone Age peoples, and helped them spread out of Africa to colonize the world. Spears made it costlier for people to attack each other, at least until people developed military organizations. This led to a nearly 400,000-year lull in group violence. Kelly’s proposal adds one to the many theories researchers have advanced to explain why humans conduct wars, and whether warfare is hard-wired in the human brain.  He based his conclusions on observations of human tribal societies and of group fighting among chimps, which has been compared to a primitive form of warfare. The period of peace, he said, may have been a bridge between an earlier era of warfare—in which our fighting was somewhat like the chimp battles—and a later one, lasting from around 14,000 years ago to today. The 2 violent periods each had different characteristics in terms of the type of violence. And the spear’s invention, he claimed in the paper, was a major turning point. In the chimp battles that some researchers compare to warfare, the primates have been observed getting into fights as they roam the borders of their group’s territory. If a group of chimps encounters a lone chimp in that area, the group will sometimes take advantage of its numerical advantage to gang up on the lone chimp. A brutal death then ensues. Some anthropologists have theorized that in evolutionary terms, this is a strategy to whittle away the strength of a neighboring group, in order to more easily encroach on its territory for food later. In fact, people may have used similar strategies hundreds of thousands of years ago. But the spear made such tactics obsolete. With killing at a distance possible, strength in numbers was no longer a deciding factor. Thus, invading a neighboring territory no longer paid off. Defenders usually had superior numbers in the area overall; better knowledge of the territory; and often the advantage of surprise, made possible by the ability to kill from afar. With fighting no longer a profitable option, cooperation took over as a dominant strategy. Cooperation sometimes entailed one group moving away from another group, to go hunt elsewhere, rather than invading the other group’s hunting grounds. This may have been a factor in humanity’s spread out of Africa to colonize the rest of the world, a dispersal that many scientists estimate took place sometime between 45,000 and 80,000 years ago. The long period of peace came to an end, when humans developed more effective military organizations. Previously, fighting had been the province of hunters who basically freelanced as warriors. This wasn’t conducive to all-out war. But later, this equation changed radically, as true warriors emerged. This facilitated the mobilization of all adult male group members and their participation in preplanned dawn raids on settlements in which the tactical advantages of surprise and numerical superiority could be brought to bear. At this juncture, the unit involved in combat is a raiding party… rather than a hunting party. And the location of combat shifts from the border zone to the sleeping quarters at the core of a group’s territory. This led to the “origin of war” in the modern sense of the word. (Kelly, PNAS)



• Web resources :
• dmoz Open Directory Project (ODP) : Sociobiology
• The Virtual Library - Anthropology
• Primate Info Net
• Human Origins Program of Smithsonian Institute
• Institute of human origins
• Leakey Foundation

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