Little Foot.

In the late nineteen thirties, palaeontologist Robert Broom discovered a series of Hominin skeletons in a cave system in Sterkfontain, South Africa. These, he assigned to the genus Australopithecus, which had been described in 1925 by Raymond Dart, suggesting that he had found a second species in the same genus. At the time, these discoveries did not receive a great deal of attention from the international scientific community. The cave deposits at Sterkfontain were estimated by Broom to be Late Pleistocene in age. This made Broom's material much younger than Dart's and contemporary with modern Human remains from many parts of the world, which meant that, while interesting, Broom's new 'Ape-man' could not be ancestral to modern Humans.

More locally, however, the discoveries caused considerable interest, leading many amateur fossil hunters to begin exploring the Sterkfontain cave system. One of these was Helmut Kurt Silberberg, a Johannesburg art dealer and antiquarian with an interest in prehistory. In 1942, Silberberg's explorations led to the discovery of a small cave with numerous bones embedded in the walls. Unfortunately, the rock in which the bones were embedded was extremely hard (more so than the bone) making excavation difficult. Silberberg paid a local man to hammer free a chunk of rock, during which process several bones were broken, displeasing Silberberg. When the bones in the rock were examined, they were found to belong to a Hyena and a Baboon. 

Discouraged by these findings, Silberberg lost interest in the work, giving his specimens to Broom, and moving onto other projects. While the fossils were not interesting to Silberberg, the material proved to be much more useful to Broom, who recognised the Hyena as a member of the genus Lycyaena, which was otherwise known from the Early Pliocene of Europe and India. Even if this South African specimen was younger than other fossil Hyenas assigned to the genus, it was unlikely to be Late Pleistocene in age. This caused him to re-evaluate the age of the cave system using Mammal fossils to establish an age sequence, which proved that his Australopithecus fossils were much older, and therefore much more significant, than he had originally realised. Broom named the Hyena fossil Lycyaena silberbergi (a name which is no longer used) and the cave where it was found was eventually named Silberberg Grotto.

In 1966, palaeoanthropologists Philip Tobias and Alun Hughs began a new series of excavations at the Sterkfontein Caves, working methodically through the cave system from west to east, and uncovering several new specimens, albeit mostly fragmentary. In 1978 they revisited Silberberg Grotto, removing large sample of breccia, which was cleaned by technicians at the site to recover a larger amount of fossil material, most of which was moved to the University of the Witwatersrand, while some remained in storage at Sterkfontein.

From left to right, Raymond Dart, Alun Hughes, and Phillip Tobias at Witwatersrand University in the mid-1970s. Clarke & Kramer (2012).

In 1992 Tobias' team returned to Silberberg Grotto, this time employing two mining engineers, John Cruise and Dusty van Rooyen, to blast away a section of the fossil-rich wall of the cave. Analysis of the material recovered by this process in 1994 by palaeoanthropologist Ronald Clarke revealed something surprising. The rocks had produced numerous bones associated with Carnivores and Monkeys, but for some reason almost no Bovids (usually the most abundant Mammals in South African deposits). This led him to return to the material stored at Witwatersrand, which he also analysed for the proportions of different Mammal groups. 

While examining this material, Clarke discovered what appeared to be the talus, navicular, medial cuneiform and proximal half of the first metatarsal of an unknown Hominin. This was surprising for two reasons. Firstly, the material had been examined previously by specialists palaeoanthropologists looking for exactly this sort of material, and secondly because the Silberberg Grotto had by this time been identified as somewhat older than the previous Hominin-producing deposits at Sterkfontein, implying any fossil Hominin found here could be the oldest yet identified specimen from the cave system. In addition to these four bones, Clarke found what appeared to be a badly damaged lateral cuneiform from the right foot, and a fragment of a possible Hominid calcaneum.

This material suggested a small Hominin, capable of standing upright like a Human, but still retaining an disposable big toe like an Ape, which suggested that at least some of its time was still spent within the trees. This specimen was given the official designation StW 573, but quickly became known as 'Little Foot'.

In 1997 Clarke discovered a box labelled 'D18 Cercopithecoids' (Old World Monkeys), which when inspected was found to also contain material labelled 'D20 Cercopithecoids'. Since D20 implied the layer of material exposed at Silberberg Grotto, and Clarke was interested in the fauna of this cave, he took down this box to inspect its contents. Within this material he found a Hominid intermediate cuneiform, which he found fit with the lateral cuneiform associated with Little Foot. Along with this was the left lateral cuneiform, the proximal end of the left second metatarsal and the left distal fibula. A subsequent search of related material uncovered the disto-medial portion of a Hominid tibia. This did not fit exactly with the Little Foot talus, but was close enough that, once the damage to the material was taken into account, Clarke considered it likely to have come from the same individual.

This tibia had a break across its shaft consistent with the sort of damage caused by mine blasting, Clarke next turned to the material stored at Sterkfontein. Here, in a bag of material labelled as Bovid tibiae, he found another Hominid tibia, which this time fit perfectly with the left talus of StW 573, leading him to realise that the previously discovered tibia was in fact from the right leg. Further inspection of this material also produced a second piece of cuneiform, which fit together with the one from the original Little Foot material, giving a complete bone. This had a bowl-like surface on its articular surface with the cuboid bone, indicating that these bones still articulated (could be moved relative to one-another), as in Chimpanzees, and unlike the condition seen in Modern Humans, where the two are immobilised by a keel-and-socket arrangement, which gives more stability when walking and running upright.

This gave Clarke a collection of twelve bones from the feet and lower legs of a single Hominin, including the left tibia and fibula, which joined to an articulated set of eight foot and ankle bones, and the distal fragment of a right tibia and right lateral cuneiform.

Convinced that more material might still be found in Silberberg Grotto, Clarke prepared a cast of the distal fragment of the right tibia of StW 573, which he gave to two perpetrators based at Sterkfontein, Nkwane Molefe and Stephen Motsumi. Molefe and Motsumi then searched the area exposed by blasting within Silberberg Grotto, looking for an exposed cross section of bone which would fit this cast. 

Clarke was not optimistic that this approach would work. The various excavations had turned the grotto into a cavern of some size, with exposed breccia on the walls, floor and ceiling, all of which might contain the matching bone fragment - if it was there at all. As if this was not difficult enough, there was neither natural light nor a rigged lighting system within the cave, forcing the two investigators to search using hand-held torches. 

After two days Molefe and Motsumi reported finding a bone embedded in a talus slope at the western end of the grotto, which was a perfect match for the cast given to them by Clarke. This was unexpected, as this was not the area where Cruise and van Rooyen had carried out their blasting, but an older area of excavations where blasting had been carried out by commercial miners extracting limestone for use in the construction industry, an operation which had stopped 65 years before. Furthermore, a second section of bone could be seen to the left of this bone, which turned out to be a perfect match for the broken left tibia.

Ronald Clarke, Stephen Motsumi and Nkwane Molefe. Kathleen Kuman/Mail & Guardian.

Following this discovery, Clarke, Molefe, and Motsumi began excavating the site using hand tools, taking almost a year to uncover the left tibia shaft and the distal ends with lower shafts of the left and right femurs. After which, however, the material apparently stopped, until Motsumi hammered away a section of travertine (dense limestone deposited by hot springs) higher up the slope exposing more breccia, and the distal and of a Hominid humerus and mandible. The skeleton had apparently been entombed in rock, broken in half by an ancient rockfall, and covered by travertine from an ancient hot spring, before eventually being exposed by limestone miners some time in the early twentieth century.

In the following months, and eventually years, the skull, left forearm, left hand, pelvis, ribs, vertebrae, humerus, and most of the lower limb bones were extracted. The final skeleton was 90% complete, the most complete non-Human Hominin skeleton ever recovered. For comparison, the famous Lucy (or Dink'inesh) skeleton AL 288-1, considered to be the most complete specimen of Australopithecus afarensis, is only 40% complete.

The complete skeleton of StW 573, Little Foot.  Paul John Myburgh/ University of the Witwatersrand.

The Sterkfontein cave system, now part of the Maropeng Cradle of Humankind World Heritage Site, are a karstic cave system on the south side of the Bloubank River, about 50 km to the northwest of Johannesburg. Karstic cave systems form as water percolates through limestones, dissolving some of the mineral to create voids. This is a complex process, as cave systems form, are enlarge by the hollowing-out of water erosion, then collapse bringing sediments from above down to lower levels and often redirecting the water flow which caused the hollowing out. Furthermore, the limestone dissolved in one place is typically re-deposited in another, as travertines or flowstones. All of this makes establishing timelines for the karstic deposits extremely complicated.

Sterkfontein Caves began to form about six million years ago, towards the end of the Miocene. Throughout much of the intervening time the local environment has been a mosaic of grasslands, woodlands, and lakes, albeit with warmer, wetter phases, and cooler, dryer phases. At least five different Hominin species have been found within the caves, some of whom appear to have sought shelter within cave systems, others to have been dragged their for consumption by cave-dwelling carnivores, while others appear to have fallen into sinkholes.

Skeleton StW 573, or Little Foot, was found closely associated with a large Baboon (an animal quite capable of predating a small Hominin), but does not show any signs of having been consumed. Rather, it seems to have fallen face-down into a shallow puddle of water within a sinkhole. Possibly the Hominin and Baboon fell together following a struggle, but this is guesswork we will never be able to prove. The chamber where it was found contained Pliocene Hyenas, and was directly below the chamber which produced Bloom's most famous Australopithecus specimen, Mrs. Ples (STS 5), and therefore must be older than that specimen.

In 1978, geomorphologist Timothy Cooper was part of the team led by Tobias and Hughes which re-examined the Silberberg Grotto. He established that the chamber had formed as a cone-shaped void, the walls of which had then been covered by flowstone (dissolved and then re-deposited limestone), before an opening had reached the surface, forming a sinkhole into which surface sediments, and various Animals now preserved as fossils, had fallen, filling in the cone. These sediments were then covered by a second flowstone deposit. The sediments within this cone were thought to be about 2.8 million years old (Late Pliocene) on the basis of the fossil fauna they contained, implying a similar age for Little Foot. 

However, Molefe and Motsumi had established that Little Foot had in fact come from below the lower flowstone deposit, with only a small portion displaced into the accessible sediments by an ancient rockfall and the actions of early twentieth century miners. Various attempts have been made to date this flowstone deposit, including cosmogenic uranium-lead series nuclide dating, palaeomagnatism. These studies produced dates between 4 million years and 1.07 million years ago, although most fell into the range between 2.8 and 2.2 million years ago. However, subsequent studies also established that the flowstone itself contained pockets of younger, redeposited material, making all dating of this layer suspect.

Cosmogenic aluminium²⁶ and beryllium¹⁰ dating works because both aluminium²⁶ and beryllium¹⁰ are produced in quartz exposed to cosmic rays (i.e. on the surface) at a steady rate, producing a ration of 6.75 aluminium²⁶ to 1.0 beryllium¹⁰. Once the quartz is buried no more of either radioisotope is formed. Since the half-life of aluminium²⁶ is roughly half that of beryllium¹⁰, over time the ratio between the two radioisotopes will change, enabling the precise measurement of both how long a piece of quartz was exposed on the surface, and how long ago this happened. In April 2015 a study led by Darryl Granger of Purdue University produced a date for the sediments in which StW 573 was directly lying, based upon cosmogenic aluminium²⁶ and beryllium¹⁰, yielding an age of 3.67 million years before the present (equivalent to the dates for early Australopithecus afarensis specimens from East Africa. 

Darryl Granger. Lena Kovalenko/Purdue University.

This also makes StW 573 the oldest Hominin fossil discovered in South Africa, as well as the most complete pre-Human Hominin fossil ever found. It also predates the oldest stone tools in South Africa by over a million years, and the oldest known stone tools anywhere by over 300 000 years, suggesting that it came from a population which did not yet have this technology. 

Studies of Little Foot have suggested that she was female, and stood about 1.20-1.30 m tall, with longer legs than arms (similar to modern Humans, but unlike Chimpanzees). She had an 'S' shaped collarbone, which is a more Human-like trait, and but the shape of her pectoral girdle and shoulder blades, suggest that she was comfortable moving in trees suspended by her arms. The structure of its foot suggests that it was able to walk in an erect manner, similar to modern Humans, but still had an opposable big toe, implying it was still a comfortable climber (Pliocene Hominins are in general thought to have been woodland species, with the preference for open grasslands emerging in the Pleistocene when a cooler, dryer climate led to the retreat of forests and expansion of grasslands). 

This fits well with the environment in which her remains were found. While the Silberberg Grotto produced the remains of some terrestrial Animals, such as Antelope and Hyenas, the majority of the fossils are of Animals associated with an arboreal lifestyle, such as small Monkeys and Felids. Such Animals might have climbed down into the sinkhole in order to obtain water and become trapped, or possibly have fallen directly from trees into the hole - in Little Foot's case, possibly while trying to escape from a large Baboon.

Surprisingly, despite the completeness and significance of Little Foot, she has never been assigned to a specific species. She was referred to by Ronald Clarke as possibly a specimen of Australopithecus prometheus. However, this species name is now considered to be invalid; it was used by Raymond Dart to refer to a partial occipital bone (part of the back of the skull) from Makapansgat, but this has now been assessed as a specimen of Australopithecus africanus, a species common in South Africa from about 3.3 to about 2.1 million years ago. However, Little Foot is not generally accepted as belonging to Australopithecus africanus, which it predates as well as differing from in its brain capacity (smaller in Little Foot) and shoulder arrangements (more Ape-like in Australopithecus africanus). Nor does she conform to Australopithecus afarensis, a species whose time range she overlaps, but which is not found in Southern Africa. 

Thus Little Foot appears to be an otherwise entirely unknown species of Australopithecus from South Africa, with an arboreal lifestyle and no use of stone tools. This is not completely surprising, as species such as Australopithecus africanus and Australopithecus afarensis are clearly already some way removed from their closest Ape relatives. and species which live in trees seldom have good (if any) fossil records.

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The origin of the ancient Dembeni people of the Comoros Islands.

When the first Europeans reached the Comoros Islands in the late fifteenth century, they found a group of small independent city-states forming part of the 'Swahili Corridor', a system of small island and port-city states which stretched up the east coast of Africa, also including cities on Madagascar and the coasts of what today are Mozambique, Tanzania, and Kenya. These states were bound together by a common language, Swahili, and a common religion, and traded slaves and African goods with the Middle East and other areas of the Indian Ocean rim. Local legend had it that the people of the Comoros were descended from King Solomon and the Queen of Sheba, and that upon hearing of the Profit Mohammed, an emissary was sent from the islands, who returned bringing with him the Islamic faith, and built the first mosque in the archipelago on the island of Ngazidja. European ethnologists concluded that the Swahili culture came about as Arab traders moved down the coast of East Africa, taking local women as wives (or, in more lurid accounts, concubines). 

The position of the Comoros Islands in the Mozambique Channel. The island of Ngazidja is now more commonly known as 'Grand Comoros', and is home to Moroni, the capital of the Union of the Comoros, which gained independence from France in 1979 as the 'Federal Islamic Republic of Comoros', adopting its current name in December 2001. The island of Moare remained a French possession, now forming the Department of Mayotte. Wright (1975).

In the 1970s and 80s a series of archaeological digs were carried out in the Comoros. The earliest culture uncovered by these excavations was identified as the 'Dembeni Phase', in reference to the location where it was first discovered, close to the village of Dembeni on the island of Moare (now the French department of Mayotte). Overlying this in places were layers assigned to the more widespread 'Hanyundru Phase', which can be clearly associated with medieval Swahili culture, with buildings made from stone or coral and cement, and imported Middle Eastern Glassware.

Six sites were associated with the Dembeni Phase, Dembeni itself plus Old Sima on the island of Ndzuwani (now more commonly known as Anjouan), M'Bachile, Dzindani, and M'Beni, on the island of Ngazidja (now usually referred to Grand Comoros), and M'Ro Deoua on Mwali (now usually Mohéli). The Dembeni people built small-to-medium sized villages, comprising houses built from wooden posts with a mud covering, on beaches or ridge-tops, always close to lagoons, and with access to freshwater streams. They consumed significant amounts of seafood (Fish, Shellfish, and Turtles), and kept Carrle and Goats, and farmed crops such as Rice, Millet, and Coconuts, which are still common across the region today.

The Dembini people produced distinctive pottery, with two distinct styles found on the islands and thought to have been made locally. The first of these is plain, with a smooth exterior and a burnished interior, sometimes embellished with a band of incisions or shell imprints. The second is covered with a red slip, either on the interior or the exterior, or both, and is typically burnished and decorated with graphite. In both cases the clay used was course and contained particles of red, grey, and white grit, although the former was typically courser. This courser, plainer style was used to make jars and pots, many of which show signs of being used for cooking. The finer, more decorated, style was used to make shallow bowls, possibly for serving food. A single bead made from local pottery was found at Dembeni,

Examples of 'plain' Dembeni-ware pottery from (a) Dembeni, (b) Sima, (c) M'Ro Deoua, (d) Dembeni, (e) Sima, (f) Dembeni, (g) M'Beni, (h) Dembeni, (i) Dembeni, (j) Dembeni, (k) Dembeni, (l) M'Bachile, (m) M'Bachile, and (n) Sima. Carla Sinopoli in Wright (1984).

Dating of the Dembeni sites was difficult with the technology available in the 1970s and 80s. Attempts were made to obtain carbon¹⁴ dates from several items. A shell collected from a midden at Sima yielded a carbon¹⁴ date of 1550±70 years before the present. Since it was understood by this time that it was necessary to adjust dates from shells to take into account for the carbon¹⁴ content of the atmosphere and the ocean in which the shell had formed, this was interpreted as indicating a date of about 910 AD, with a 96% probability of a date between 785 and 1040 AD. A piece of charcoal from M'Bachile yielded a carbon¹⁴ date of 1140±60 years before the present, with a 96% chance of a date between 470 and 650 AD, while a second piece of charcoal from Sima yielded a carbon¹⁴ date of 1960±70 years before the present, with a 96% chance of a date between 155 BC and 215 AD. At first sight, these dates seem incompatible, sine the Dembeni culture is not thought to have persisted for many centuries, but dates obtained from charcoal represent the age of the original wood from which the charcoal was made, and if this wood came from the interior of a tree, may be much older than the burning event.

Another way to determine the age of archaeological sites is by comparing goods from them to similar items from other sites with known chronologies. Although the majority of the recovered material from the Dembeni sites appears to have been local in origin, items from further afield were found at all locations, together representing about 4% of the recovered ceramics. 

Among the items found at M'Ro Deoua were several large basins and the neck of a large pithoi (large storage jar) made from an oxidised yellow-green clay. These items were made from a base-material which contained fragments of older pottery and fragments of igneous rock, and were decorated with chopped-grass impressions. Smaller fragments of the same material were also found at Dembeni and Sima. This pottery resembled similar material known from several sites in the Near East, at sites dated to between the eighth and tenth centuries AD, although this pottery had never been the subject of any detailed study.

A second type of non-local pottery, found at all sites except Dzindani, comprised fragments of large sandy-ware jars decorated with incisions and barbotine appliqué, with a blue-green glaze on the external surface and an speckled grey or grey-green glaze on the interior surface. Similar jars are known from Siraf on the Gulf Coast of Iran, where they first appear in the eighth century, and on Manda Island, Kenya, where they are found alongside ninth-to-tenth century Chinese ceramics. 

The most common form of imported pottery, found at all of the Dembeni sites, were small fine bowls with a white glaze, typically with a splash of coloured glaze on the interior; the colour of this varies, with the most common being cobalt, turquoise, or gold. Similar bowls are known at Susa in southwest Iran, where examples with cobalt on the interior appear around 720 AD, while turquoise does not appear until about 820 AD, as well as at Shiraf, where cobalt appears around 800 AD and turquoise around 850. This may offer some insight into the chronology of the Dembeni sites, as only white pottery is present at M'Ro Deoua, cobalt at Dembeni, and turquoise at M'Bachile and Sima.

As well as pottery, glass fragments were found at Dembeni, Sima, M'Ro Deoua, and M'Bachile. These were greenish, yellowish, clear, or cobalt blue, and round or cylindrical in shape. All appeared to have been blown, and resembled glassware forms widespread in the Near East. A number of iron items, and slag from iron forging were also found. While it was unclear where these had come from, iron is not a locally available resource in the Comoros. 

All of this appeared to show that the Dembeni people occupied the Comoros between about 800 and 1000 AD, and that from the very earliest, they had strong trading connections with the Near East. This apparently supported the idea that they were migrants from this area, rather than the east coast of Africa. However, two grave sites were also found associated with one of the Dembeni sites, Ngazidia. These both had their heads facing to the south, at odds with Islamic custom, making it highly unlikely that they were Muslims, which would almost certainly have been the case with Near Eastern emigrees of the period.

Founded in 2008, the Sealinks Project seeks to study the movements of ancient peoples and development of trading routes around the Indian Ocean. One of the problems this has sought to resolve is the peopling of Madagascar by settlers from Southeast Asia, and the subsequent adoption of Southeast Asian crops, such as Rice, Coconuts, and Mung Beans into the cultures of the Swahili Corridor. Madagascar was settled in the first millennium BC by hunter-gatherers from Africa, but agriculture appeared to have arrived on the island much later, with settlers from Southeast Asia, and today about 10% of Madagascar's flora is of Southeast Asian origin, either crop plants of weeds introduced along with them.

Between 2010 and 2013, archaeologists from the Sealinks Project carried out excavations at early sites on Madagascar and the Comoros, and settlements of the Swahili Corridor on the coast and offshore islands of East Africa, looking for early examples of both African and Southeast Asian crops, which were then dated using modern radiocarbon methods. Unsurprisingly, Southeast Asian crops were almost absent from the African sites, with only small quantities found at the largest and most active ports. On Madagascar, Southeast Asian crops appear abruptly around 1000 AD, with no evidence of any agricultural activity before this point. Surprisingly, the Comoron sites associated with the Dembeni Culture were also overwhelmingly dominated by Southeast Asian crops (only Sima produced small amounts of African crops such as Millet), and these appeared around 750 AD, significantly earlier than on Madagascar.

(A) Map of eastern Africa, including the Comoros and Madagascar, showing the locations of sites included in the crop study. The relative proportions of African and Asian crops are shown for each site (percentages based on numbers of identified specimens per site). (B) Chronological summary of African vs. Asian crop patterns by site from north to south. Crowther et al. (2016).

This raised some surprising questions. The reliance of the Dembeni people on Southeast Asian, rather than African or Middle Eastern crops, suggests that they did not come from either of these areas, but were instead of Southeast Asian origin, potentially part of the great Austronesian migration of peoples from the Malaysian Peninsula through the Islands of Indonesia and on as far as Hawai'i and New Zealand, but also westward to Madagascar. With the Comoros having apparently been settled before Madagascar, it is possible that the larger island was secondarily settled by the Dembeni people, although it is also possible that older sites on Madagascar have not been located.

The modern people of the Comoros are not obviously Southeast Asian. They appear similar to the peoples of East Africa, and speak a language (Comorian) which belongs to the Sabaki language group, which is otherwise spoken along the Tana River of Kenya, and surrounding parts of the Kenyan coast. Their closest cultural links are with the Swahili culture of coastal Kenya, Tanzania, and Mozambique, itself thought to have derived from the Middle East through trade along the east coast of Africa. Possibly this could indicate that the Dembeni people, although the first settlers of the Comoros, did not survive contact with later settlers from East Africa or the Middle East.

With this in mind, a project led by scientists from the Laboratoire d’Anthropologie Moléculaire et Imagerie de Synthèse at the Université de Toulouse carried out a study in which the genomes of volunteers from the Comoros and coastal Swahili communities in Kenya were compared to an extant database, containing genomes from Africa, Madagascar, the Middle East, Southeast Asia, South Asia, East Asia, and Europe.

Surprisingly, despite long-held assumptions about their having Middle Eastern ancestry, the Kenyan Swahili populations were found to be of entirely sub-Saharan African ancestry. The Kenyan Swahili populations were found to have a homogeneous structure, all more closely related to one another than to any other group, and to be more closely related to Bantu-speaking populations than any other African group. Some of the Kenyan Swahili individuals had recent Somali ancestry, but otherwise the Swahili populations were strongly isolated from Somali and Ethiopian populations. The Comorian and Malagasy populations were more closely related to the Kenyan Swahili populations than to any other African population, although both had admixtures of Southeast Asian ancestry, which made up between 33 and 39% of the ancestry of the Malagasy populations, and 8-9% of the ancestry of the Comorians. Curiously, despite being further south than the Kenyan Swahili populations, the Comorians also had some Middle Eastern ancestry, which made up 6-7% of their genomes.

A statistical model of the ancestry of modern Comorians suggested that their common ancestry formed as a distinct population between 1197 and 792 years before the present, with the admixture of a Swahili and a Southeast Asian group. Different islands within the group have also had subsequent influxes of genetic material from Swahili, Middle Eastern, and Southeast Asian populations. The Madagascan populations showed a more recent origin, with an admixture between a Swahili Group and an Island Southeast Asian group between 876 and 742 years before the present (this population appears to have arrived in the area separately, and not to have migrated from the Comoros). 

Admixture Scenario for Populations along the Swahili Corridor as Estimated by GLOBETROTTER and ADMIXTURE Dark red arrows represent Swahili gene flow; light green arrows represent Island Southeast Asian Banjar or Malay; a yellow arrow represents Middle Eastern gene flow; and the purple arrow represents gene flow from the Horn of Africa. The pink arrow represents gene flow from central and southern Bantu speakers. Dates refer to the last detectable admixture event; dates below pie charts refer to the admixture event between the Swahili and Banjar or Malay; dates in italics represent secondary gene flow. Sex-biased gene flows are represented by male and female symbols in the tip of the arrows; note that they are not presentin Malagasy Antemoro and Comorian Moheli. Brucato et al. (2018).

Thus, the most likely scenario is that the Dembeni people reached the Comoros Islands from Peninsula Malaysia or Island Southeast Asia around 750 AD. They brought with them staple crops from Southeast Asia, as well as Cattle and Goats, and fished in the islands' lagoons and surrounding seas. They exchanged trade goods with the Near East, probably through early East African Swahili intermediaries, with whom they may have intermarried. Despite this cultural exchange, the Dembeni appear to have remained a distinct culture till around 1000 AD, when they were abruptly replaced by the Hanyundru culture, which appears to have been more distinctly Swahili in nature. Modern Comorians derive about 8-9% of their genetic ancestry from this group, and still farm many Southeast Asian crops, but speak a language of apparent Kenyan origin, and are culturally close to the Swahili populations of East Africa.

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