Tuesday, 28 September 2021

Nasalis larvatus: Estimating the conservation status of the Proboscis Monkey on the Klias Peninsula, Borneo.

Almost half of all non-Human Primates are considered to be threatened by habitat loss due to Human activities, principally the clearing of forests for urban expansion, agriculture and agroforestry, or simply timber. Primates are thought to be particularly vulnerable to these pressures due to their long life-cycles and slow breeding rates, requiring access to a range of forest resources, which in turn makes it hard for them to adapt to changes to their environments, particularly those driven by Humans. Because of this, conservation efforts directed at Primates need reliable information on the distribution of Primates and the resources upon which they rely.

The forests of Southeast Asia are considered to be of international importance by conservations, with a number of biodiversity hotspots. These forests have come under considerable pressure in recent years, with huge areas cleared for agriculture, principally the cultivation of Oil Palms, Elaeis guineensis. Particularly threatened by this expansion are the forests of Borneo, an island with a high level of endemism (i.e. species not found anywhere else) where large areas of forest have been cleared to make way for Oil Palm plantations, and where, in addition to the direct loss of forests, many wildlife populations are additionally threatened by hunters making use of the road networks put in to support the Oil Palm industry.

Proboscis Monkeys, Nasalis larvatus, are large, sexually dimorphic Monkeys endemic to Borneo, which are considered to be Endangered under the terms of the International Union for the Conservation of Nature's Red List of Threatened Species. They get their common name from the prominent noses of the adults, these being more distinctive in the larger males than the smaller females. These Monkeys typically live in groups with a single male, plus several females and their young, although groups of young males are also found. The species is found in lowland forests close to water, such as riverine forests, mangroves and peat swamps, environments which are increasingly threatened by the expansion of Oil Palm cultivation, which is typically carried out on lowland floodplains. This expansion is known to have caused problems for Proboscis Monkeys, with their habitat increasingly being fragmented into smaller areas.

A male Proboscis Monkey, Nasalis larvatus, in Borneo. Mark Louis Benedict/Rainforest Rescue.

In 2004 a survey of the Klias Peninsula on the eastern tip of the Malaysian state of Sabah, found 569 individual Proboscis Monkeys living in groups, while a second survey carried out in 2005, which surveyed forests along the major rivers and tributaries of Sabah State by boat, found 818 Proboscis Monkeys on the Klias Peninsula, living in 75 groups. Both surveys found that the Klias Peninsula population was the largest surviving population in the state, and probably the only population large enough to have long-term survival prospects. This reliable presence of Proboscis Monkeys has turned the Klias Peninsula into somewhat of a tourist centre, with a number of companies offering opportunities to view the Monkeys.

In a paper published in the journal Raffles Bulletin of Zoology on 9 June 2021, Henry Bernard of the Unit for Primate Studies-Borneo at the Universiti Malaysia Sabah, Nicola Abram of Forever Sabah, Menaga Kulanthavelu and Felicity Oram, also of the Unit for Primate Studies-Borneo at the Universiti Malaysia Sabah, and Ikki Matsuda, again of the Unit for Primate Studies-Borneo at the Universiti Malaysia Sabah, and of the Academy of Emerging Sciences at Chubu University, the Wildlife Research Center of Kyoto University, and the Japan Monkey Centre, present the results of a previously umpublished survey of the Proboscis Monkeys of the Klias Peninsula, undertaken in 2014, combined with a comparison of this survey to the 2004 survey, undertaken with a view to understaning any changes in the population over a ten year period.

The Klias Peninsula has an area of about 1300 km², and is genrally flat, with a maximum elevation of about 50 m above sealevel. Historically, the peninsula was covered by complex mixture of Mangrove, Nipah Palm forest, freshwater swamp forest, and peat swamp forest, interspersed with open areas and extensive wet grasslands, but much of this has been cleared to make way for small scale Human settlements and farming, as well as larger Rubber and Oil Palm plantations. Bernard et al. carried out surveys by boat, along the Padas, Padas-Damit, Klias, and Bukau rivers, concentrating on areas where Proboscis Monkey populations had been detected by the 2004 and 2005 surveys. These included the Padang Teratak Bird Sanctuary, the Padas Damit Forest Reserve, the Menumbok Forest Reserve, the Binsulok Forest Reserve, the Klias Forest Reserve, the Kg. Hindian Forest Reserve, and the Nabahan Forest Reserve.

The Klias Peninsula region in western Sabah, in the northern part of Borneo (inset), Malaysia, and the research sampling sites in riverine, Mangrove, and mixed Mangrove-riverine forests along rivers in Padang Teratak Bird Sanctuary, Padas Damit Forest Reserve, Menumbok Forest Reserve, Binsulok Forest Reserve, Klias Forest Reserve, Kg. Hindian Forest Reserve, and Nabahan Forest Reserve, where the river surveys of the sleeping sites of Proboscis Monkeys were conducted. Bernard et al. (2021).

Proboscis Monkeys are almost always found close to water, favouring flooded forest environments, so boat surveys are generally the best way to survey them. These Primates return to a communal roost in a tree by a riverbank each evening, which makes surveying them relatively easy, particularly if this is done first thing in the morning, before they leave the communal roost, or late in the afternoon, after they have returned to it. Therefore, Bernard et al. carried out surveys of Proboscis Monkeys between 5.30 and 9.30 am and between 4.00 and 6.30 pm, between January and March 2014. All of the main rivers and tributaries in the study area were surveyed once only, to prevent double counting. Where waterways were close together they were surveyed on the same, or at least consecutive, days, for the same reason. A total of 106 km of waterways was surveyed, in sections ranging from 6.5 to 21.7 km. The locations of trees with Monkeys in them were recorded accurately with a GPS receiver, as were the number of Monkeys in each tree, and the type of group present (single male with females or all male group), and the type of forest the location was in (Mangrove, riverine, or mixed Mangrove-riverine). The extent of each habitat type was also recorded by length along the riverbanks, and the preference of the Monkeys for each habitat calculated from this.

Bernard et al. also carried out a number of vegetation surveys. There were carried out on 40 m circular plots, with 4-6 at each site, for a total of 34 plots. Within these plots all trees with a trunk-thickness greater than 10 cm at breast height were assessed, in order to work out the total area of all the tree stems within each plot, the largest tree within each plot, and the species richness at each plot.

To assess the amount of Human disturbance at each site, Bernard et al. used two measures; the distance from the centre of each site to the boundaries of the three closest agricultural sites, and the distance from the centre of each site to the boundaries of the three closest Human settlements.

Bernard et al. estimated the abundance of Proboscis Monkeys at each site by dividing the number of Monkeys by the area of the site, then used this measure to compare to the total area of all the tree stems within each plot, the species richness within the plot, and the size of the largest tree, as well as the distance to agricultural land and Human settlements.

Bernard et al. attempted to esitmate the loss of available habitat to the Proboscis Monkeys by calculating the potential range as being all the land 1 km inland of all the surveyed rivers, calculating the land cover throughout this area for both 2004 and 2014 using Landsat and Google Earth imagery, then calculating the change from suitable to unsuitable for Monkey habitation, based upon the parameters established by the ground surveys.

Finally, Bernard et al. calculated the amount of Monkey habitat currently within protected areas, using data from the Sabah Forestry Department, as well as the extent of the habitat outside these protected areas upon which titles have been granted for large scale plantations or other agribusiness enterprises (typically Oil Palm growth), what proportion is under Native Titile (reserved for the use of indigenous people), and what proportion is under, or available for County Lease (available for development for any purpose, and therefore again likely to be converted to Oil Palm planting), as well as land that was either no form of title, or for which the title was impossible to determine.

During 35 days of fieldwork on the Klias Peninsula, Bernard et al. carried out 42 surveys at seven study sites. They found 679 Proboscis Monkeys living in 75 groups; 44 groups comprising a males and a group of females plus their young, 16 groups of young males, and 15 groups whose composition could not be determined. The Monkeys were at their most abundant in the Padas Damit Forest Reserve in the central part of the peninsula, where there were 200 Monkeys living in 21 groups. Proboscis Monkeys were only found in Mangrove and riverine forests, giving them a total available riverbank habitat of 105 km (65 km of Mangrove forest, 35 km of riverine forest, and 5 km of mixed Mangrove and riverine forest). More Monkeys were found in Mangroves (412) than riverine forest (267), although once the greater availability of Mangroves was taken into account, this indicated a preference for riverine forests (where there were an average of 7.6 Monkeys per km) over Mangroves (where there were an average of 6.3 Monkeys per km).

Within these three forest types there was a significant variation in the vegetation, which also appeared to influence the abundance of Proboscis Monkeys. The species richness of the forests did not appear to be important to the Monkeys, but the total trunk basal area (a measure of tree maturity) was important, with more Monkeys being found where this was highest, possibly because mature trees are important for roosting sites. The closeness of Human habitation or agricultural land did not appear to be a problem for the Monkeys.

Between 2004 and 2014 the Klias Peninsula lost 11 520 m² of intact forest, most of it riverine forest (11 450 m²). In addition, 11 960 m² of degraded forest (forest which still existed as woodland but had lost much of its original biodiversity) and swampland were lost. During the same time the area of Oil Palm plantations within Proboscis Monkey habitats grew by 23 210 m², although 21 860 m² of this (94%) was later judged to be economically unprofitable due to flooding and swampy conditions.

Within the total potential range of the Proboscis Monkeys in 2014, 49% was covered by Mangrove forests, 11% by 'other forest types' (presumably riverine forest), and 18% by degraded areas and swamps, suggesting that 78% of the species total range was covered by suitable habitat and 18% by marginal habitat. The remaining parts of the range were covered by Oil Palm plantations (14%), community agriculture (7%) and aquaculture (1%), all unsuitable habitats for Monkeys.

Much of the remaining potential habitat is not protected, with only 20% of riverine forests and 59% of Mangroves having protected status (i.e. 52% of the remaining suitable environment). In addition 6% of degraded forests and swamplands are protected. This means that 80% of riverine forests, 41% of Mangroves, and 94% of degraded forests and swamplands are at risk of being lost.

Of the remaining forests, 14% (19% of the riverine forest and 13% of the Mangroves) was in Production Forest Reserves, 16 920 m² (all of it Mangroves) in Class V Mangrove Forest Reserves and 29 360 m² (11 820 m² of riverine forest and 17 540 m² of Mangroves) was in Class IV Amenity Forest Reserves, where some commercial exploitation is allowed.

About 27% of the remaining forests (including intact and degraded forests and swamps) is on land which has been granted for development. This toral includes 43% of remaining riverine forests, about 13% of Mangroves, and around 35% of degraded forests and swamps. Furthermore another 16-17% of each forest type is located on State Land, for which permits for use could potentially be issued.

Land use and land cover data for 2014/2015 within the 1-km buffer distance from surveyed rivers, overlaid with Proboscis Monkey sightings from the 2004/2005 and 2014 surveys, Protected Areas, and Production Forest Reserve boundaries. Bernard et al. (2021).

Bernard et al. discovered populations of Proboscis Monkeys at all of the surveys locations on the Klias Peninsula, with the largest population on the central part of the peninsula. This suggests that the area can be seen as a population stronghold for the species. The distribution of the Monkeys was similar to that observed in 2004 and 2005. The 2004 and 2005 surveys found 569 individuals in 65 groups, and 818 individuals in 75 groups, respectively, to which the 679 individuals in 75 groups found by Bernard et al. compares favourably. It is likely that the differences in Monkey numbers between the counts relate to the erratic nature of Monkey behaviour and the difficulties of surveying these primates in tropical wetland environments rather than actual fluctuations in the population, and, therefore, that the population remained fairly constant between 2004 and 2014). This would appear to correlate with the limited loss of environment suffered by the Monkeys between 2004 and 2014, during with time only 2% of riverine forests disappeared, and no Mangroves.

The Monkeys were not evenly distributed throughout their environment, apparently prefering riverine forests to Mangroves, and Mangrove forests to all other environments, including mixed riverine/Mangrove forests (although the avoidance of this later environment might be an artefact, as onlu 5 km of this environment was surveyed during the study). Studies in other areas have suggested Probiscis Monkeys prefer riverine forests to either Mangroves or mixed riverine/Mangrove forests, probably due to a higher plant diversity and greater variety of food in this habitat, although Mangroves are still clearly also an important habitat.

The presence of large trees appeared to be particularly important to these Monkeys, probably because of their role as roosting sites. Larger trees both provide a greater number and variety of nesting sites, but also provide a greater distance between these sites and the ground, making it harder for predators to reach the resting Monkeys undetected.

The study did not find any direct impact on Proboscis Monkey populations made by the proximity of Human settlements of agriculture, although this may have been due to the small size of the survey. The largest threat to wildlife populations on Borneo is currently considered to be the expansion of Oil Palm plantations, and, as with other Primate species, Proboscis Monkey's tend to avoid these environments, which are comprised of extensive monocultural stands of an unfamiliar fruit tree. Other than this however, Proboscis Monkeys seem to be relatively tolerant of the presence of Humans, and will even roost close to Human settlements if that is where suitably large trees are to be found. 

Little forest was lost on the Klias Peninsula between 2004 and 2014, but there is clearly the potential for much more to go, with the 28% of riverine forest currently designated for development being of particular concern. Grants of land made under such schemes in Sabah come with time limits; i.e. if the holder does not use the land within a certain period of time, then they lose the title, which can be granted to another user. These schemes currently make no provision for the retention of intact forest, clearly creating an incentive for developers to fell such forests to retain control of the land. As such Bernard et al. strongly recommend that the law be changed to allow landowners to leave areas of forest intact in order to protect the Proboscis Monkeys.

Also of concern are the large areas of forest designated as Production Forest Reserves, particularly the area within the Padas Damit Class IV Amenity Forest Reserve, which is the area with the greatest population of Proboscis Monkeys. These areas were originally intended to be areas of forest which were left largely intact, but where a range of leisure activities were permitted, however a follow up study in 2017-18 found that large areas under this designation had been converted to Oil Palm cultivation.

Proboscis Monkeys require forests along river margins to survive. As such the fragmentation of such environments not only lowers the amount of available habitat, but also removes their ability to move from one area to another, as their preferred environment is essentially linear. Thus protecting the species in future will require not just careful monitoring of their population, but careful management of the areas where they live, and in particular careful monitoring of land use changes likely to have an adverse effect.

Bernard et al. feel it would be particularly useful to grant full protection to Proboscis Monkeys living on government land, as this would have the issuing of land grants within areas of Monkey habitat, and allow the designation of protected areas to protect the Monkeys.

The Klias Peninsula is a popular tourist destination, and viewing Proboscis Monkeys is a popular activity with tourists. Thus good management of the Monkey population is likely to be of economic as well as conservational benefit, drawing tourists to Sabah, and generating income for local communities.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter

Tuesday, 21 September 2021

Miner killed in roof-collapse in central Queensland.

A miner has died and another two required hospital treatment following a roof collapse at the Sojitz Gregory Crinum Coal Mine to the north of Emerald in central Queensland. The incident happened at about 11.00 am on Tuesday 14 September 2021, when part of the mine roof collapsed onto a conveyor drift (area through which a conveyer belt runs, carrying coal to the surface). Two men were trapped beneath the fallen debris, one of whom, a 60-year-old miner who has not been named, dying as a consequence, while the other, a 25-year-old, was freed after several hours and airlifted to the Rockhampton Base Hospital with injuries to the legs and pelvis. A third worker was also taken to hospital following a 'medical episode' but discharged later the same day.

The Sojitz Gregory Crinum Coal Mine in Queensland, Australia. Rachel McGhee/ABC News.

The Gregory Crinum Mine site was acquired by Sojitz, a Japanese mining group, in 2018, and recommenced work in May 2021. The mine had previously been mothballed in 2007, in part due to concerns about the stability of the roof, which was considered to be too unstable for the type of room and pillar mining used at the site; this is a system in which a horizontal bed of the target mineral (usually coal) is removed by the excavation of a series of tunnels arranged like streets on a city block, leaving behind blocks of unmined material to support the ceiling of the tunnels.

This is the first mining fatality in Queensland since January 2020, but the ninth since July 2018, with a spate of incidents in 2018-19 having sparked a clampdown on mine safety by authorities in Queensland. Sojitz had reportedly been advertising for inexperienced workers who would be trained at the Gregory Crinum Mine site, due to a shortage of experienced mineworkers in Queensland. The incident is currently under investigation by the Queensland Police Service. 

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter

Monday, 20 September 2021

Marburg Virus alert in Guinea comes to an end.

The Ministry of Health of Guinea has declared the end of the Marburg Virus Disease outbreak in Guéckédou Prefecture, Nzérékoré Region, according to a press release issued by the World Health Organization on 17 September 2021. In accordance with World Health Organization recommendations, the declaration was made 42 days after the safe and dignified burial of the only confirmed patient reported in this outbreak. This was the first-ever Marburg Virus Disease case reported in Guinea. 

On 16 September 2021, the Ministry of Health of Guinea declared the end of the Marburg virus disease outbreak in Guéckédou prefecture, Nzérékoré Region. In accordance with World Health Organization recommendations, the declaration was made 42 days after the safe and dignified burial of the only confirmed patient reported in this outbreak. This was the first-ever Marburg virus disease case reported in Guinea.

From 3 August 2021 to the end of outbreak declaration, only one confirmed case was reported.  The patient, a man, had onset of symptoms on 25 July. On 1 August he went to a small health facility near his village, with symptoms of fever, headache, fatigue, abdominal pain and gingival hemorrhage. A rapid diagnostic test for Malaria returned a negative result, and the patient received ambulatory supportive care with rehydration and symptomatic treatment. Upon returning home, his condition worsened, and he died on 2 August. An alert was subsequently raised by the sub-prefecture public health care facility to the prefectorial department of health in Guéckédou. The investigation team was immediately deployed to the village to conduct an in-depth investigation and collected a post-mortem oral swab sample, which was shipped on the same day to the Viral Hemorrhagic Fever Laboratory in Guéckédou city. On 3 August, the sample tested positive for Marburg Virus Disease by reverse transcriptase-polymerase chain reaction and negative for Ebola Virus Disease. The deceased patient was buried safely and with dignity on 4 August, with the support of the national Red Cross.

On 5 August, the National Reference Laboratory in Conakry provided confirmation by real-time polymerase chain reaction of the positive Marburg result, and on 9 August, the Institut Pasteur Dakar in Senegal provided an additional confirmation that the result was positive for Marburg Virus Disease and negative for Ebola Virus Disease.

Negative stained transmission electron micrograph of a number of filamentous Marburg Virions, which had been cultured on Vero cell cultures, and purified on sucrose, rate-zonal gradients. Erskine Palmer/Russell Regnery/Centers for Disease Control and Prevention/Wikimedia Commons.

The Ministry of Health activated the national and district emergency management committees to coordinate the response and engage with the community. Additionally, the Ministry of Health together with the World Health Organization, the United States Centers for Disease Control, the Alliance for International Medical Action, the Red Cross, UNICEF, the International Organization for Migration, and other partners, initiated measures to control the outbreak and prevent further spread including the implementation of contact tracing and active case search in health facilities and at the community level.

During the outbreak, a total of one confirmed case who died, and 173 contacts were identified, including 14 high risk contacts based on exposure. Among them, 172 were followed for a period of 21 days, of which none developed symptoms. One high-risk contact was lost to follow up. At the different points of entry in Guéckédou prefecture where passengers were screened, no alerts were generated.

Ongoing activities include:  Capturing and sampling of Bats in the localities of Temessadou M´Boké, Baladou Pébal and Koundou to better understand the involvement of Bats in the ecology of Marburg Viruses; development of a sero-surveillance protocol in the sub-prefecture of Koundou; development and implementation of plans to strengthen Infection Prevention and Control programmes at the national and facility level including establishing and mentoring of Infection Prevention and Control focal persons, Infection Prevention and Control/hygiene committees, ongoing training of health workers and adequate procurement and distribution of supplies such as personal protective equipment; implementation of water, sanitation and hygiene measures with partners including in health facilities and communities; supporting training on community-based surveillance in Guéckédou Prefecture; and risk communication and community mobilization activities in Guéckédou Prefecture as a component of a health emergency preparedness and response action plan. 

A health worker in Gueckedou, Guinea. World Health Organization.

Marburg Virus Disease is an epidemic-prone disease associated with high case fatality ratios (24-90%). In the early course of the disease, clinical diagnosis of Marburg Virus Disease is difficult to distinguish from many other tropical febrile illnesses, because of the similarities in the clinical symptoms. Other viral hemorrhagic fevers need to be excluded, particularly Ebola Virus Disease, as well as Malaria, Typhoid Fever, Leptospirosis, Rickettsial infection and Plague. Marburg Virus Disease is transmitted by direct contact with the blood, bodily fluids and/or tissues of infected persons or wild Animals (e.g. Monkeys and Fruit Bats).

Investigations are ongoing to identify the source of the infection. Guinea has previous experience in managing viral hemorrhagic diseases such as Ebola Virus Disease and Lassa Fever, but this was the first time that Marburg Virus Disease was reported. The country has a fragile health care system due to the overburden of disease outbreaks, COVID-19 pandemic, and the recurrent threat of epidemics such as Malaria, Yellow Fever, Measles, Lassa Fever, Ebola Virus Disease, health care-associated infections, high rates of acute malnutrition, cyclical natural disasters such as floods, and socio-political unrest.

Guinea health authorities responded rapidly to the event, and measures were rapidly implemented to control the outbreak. Cross-border population movement and community mixing between Guinea and neighboring Sierra Leone and Liberia increased the risk of cross-border spread. Sierra Leone and Liberia health authorities activated contingency plans and started public health measures at the points of entry with Guinea.

The affected village is in a remote forest area located at the border with Sierra Leone, about 9 km from a main international border crossing point between the two countries. The proximity of the affected area to an international border, cross-border movement between the affected district and Sierra Leone, and the potential transmission of the Virus between Bat colonies and Humans posed an increased risk for cross-border spread. 

These factors suggested a high risk at the national and regional level, and given that Guéckédou Prefecture is well connected to Foya District in Liberia, and Kailahun District in Sierra Leone, this outbreak required an immediate and coordinated response with support from international partners. The risk associated with the event at the global level was assessed as low. 

Human-to-Human transmission of Marburg virus is primarily associated with direct contact with blood and/or bodily fluids of infected persons, and Marburg Virus transmission associated with the provision of health care has been reported when appropriate infection control measures have not been implemented. 

Health care workers caring for patients with suspected or confirmed Marburg Virus Disease should apply standard and transmission-based infection prevention and control precautions to avoid any exposure to blood and/or bodily fluids, as well as unprotected contact with the possibly contaminated environment. Infection prevention and control precautions include: Early recognition (screening, triage) and isolation of suspected cases; appropriate isolation capacity (including infrastructure and human resources); health care workers’ access to hand hygiene resources (i.e., soap and water or alcohol-based hand rub); appropriate and accessible personal protective equipment for health care workers; safe infection practices (emphasise on single-use only needles); procedures and resources for decontamination and sterilisation of medical devices; and appropriate management of infectious waste.

Infection prevention and control  assessments of health facilities in affected areas using the Infection Prevention and Control Scorecard revealed sub-optimal results highlighting the need for ongoing supportive supervision and mentorship for implementation of infection prevention and control in health care settings in addition to implementing infection prevention and control minimum requirements to support and strengthen future preparedness for emerging and re-emerging infectious diseases. 

Integrated disease surveillance and response activities, including community-based surveillance must continue to be strengthened within all affected health zones.

Raising awareness of the risk factors for Marburg Virus Disease and the protective measures individuals can take to reduce human exposure to the virus are the key measures to reduce Human infections and deaths. Key public health communication messages include: Reducing the risk of Human-to-Human transmission in the community arising from direct contact with infected patients, particularly with their bodily fluids; avoiding close physical contact with patients who have Marburg Virus Disease; a ny suspected case ill at home should not be managed at home, but immediately transferred to a health facility for treatment and isolation. During this transfer, health care workers should wear appropriate personal protective eqipment; regular hand washing should be performed after visiting sick relatives in hospital; and communities affected by Marburg should make efforts to ensure that the population is well informed, both about the nature of the disease itself to avoid further transmission, community stigmatisation, and encourage early presentation to treatment centers and other necessary outbreak containment measures, including safe burial of the dead. People who have died from Marburg should be promptly and safely buried.

To reduce the risk of wildlife-to-Human transmissions, such as through contact with Fruit Bats, Monkeys, and Apes: Handle wildlife with gloves and other appropriate protective clothing; cook Animal products such as blood and meat thoroughly before consumption and avoid consumption of raw meat; and during work, research activities or tourist visits in mines or caves inhabited by Fruit Bat colonies, people should wear gloves and other appropriate protective clothing including masks.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter

Sunday, 19 September 2021

Production of dairy products drove the expansion of the Yamnaya peoples of the Eurasian Steppes in the Early Bronze Age.

The nomadic peoples of the Eurasian Steppes have long been a source of fascination to both archaeologists and the general public, with, sometimes less than flattering, fictionalised versions appearing in popular fantasy novels such as JRR Tolkien's Lord of the Rings and GRR Martin's Game of Thrones. The later phases of these groups, such as the Xiongnu and Mongol Empires are relatively familiar, but the origins of these groups in the Eneolithic (the Late Neolithic plus the Chalcolithic, or 'Copper Age') are rather more obscure. The archaeology of these groups has been studied for a long time, but new technologies have recently shed new light on the field. For example, it has been demonstrated that European populations had a significant influx of DNA from steppe-dwelling groups during the late Neolithic. The same Neolithic steppe populations (referred to as Yamnaya by archaeologists) also have also been shown to have genetic links to the Afanasievo people of the Altai Mountains and even the peoples of Mongolia. Both archaeological and genetic data suggest extensive population movements in this area during the Early Bronze Age (roughly 3300 to 2500 BC), with links being established between the Yamnaya peoples of the Pontic–Caspian steppe and the peoples of Siberia and Scandinavia.

Thus, it is understood that the Yamnaya peoples underwent a significant expansion of their geographical range during this period, but the drivers of this expansion are less certain. One popular explanation is that innovations such as the use of Horses and wagons enabled the rapid spread of a pastoralist lifestyle across large swaths of Eurasia, and that this, combined with the consumption of dairy products, made large areas of the Eurasian steppes previously unoccupiable open to Human habitation. However, while this model provides a plausible explanation for the successes of the Yamnaya peoples, it is not, at the current time, very well supported by the available evidence. There is archaeological evidence for the use of carts and bridles in the Eneolithic and Early Bronze Age, but not for the use of Horses or dairy products.

The story of Horse domestication has long been a controversial subject in archaeology. Horse remains are known from the Eneolithic of Botai in northern Kazakhstan, but these have recently been shown to have been Przewalski's (or Mongolian) Wild Horses, Equus przewalskii, not the modern domestic Horse, Equus caballus, a species which has not confidently been found in association with Humans at sites older than the Early Bronze Age, and which cannot be confidently asserted to have been used as a riding Animal or even a beast of burden, rather than something which was being hunted, at Early Bronze Age sites. It is currently thought that Horses were not ridden, or milked, on the Eastern European steppes before about 1200 BC, and they may not have been an Animal used much by the pastorialist peoples of the period at all. 

Data on the early consumption of milk is equally lacking. Isotopic studies of Human remains have been used to suggest that dairy products were being consumed, but cannot confirm this. Palaeoproteomics (the analysis of ancient sets of proteins) could potentially be used to identify dairy consumption, but so far has only been applied to a very limited number of sites on the Eurasian steppes. Studies of the Yamnaya and Afanasievo peoples have only, to date, shown evidence of dairy consumption among a few individuals from the Eastern Steppes, and was only able to give a very ambiguous result on the producer of the peptides (short amino acid chains, or fragments of proteins) found, which was probably a Sheep or Cow.

In a paper published in the journal Nature on 15 September 2021, a group of scientists led by Shevan Wilkin of the Department of Archaeology at the Max Planck Institute for the Science of Human History, and the Institute for Evolutionary Medicine at the University of Zürich, present the results of a study which examined palaeoproteonomic evidence from dental calculus from 56 Humans from across the Eurasian steppes, dated to between 4600 and 1700 BC.

Wilkin et al. collected data from 19 Eneolithic idividuals; six from Murzikha 2, nine from Khvalynsk 1 and Khvalynsk 2, one from Ekaterinovka Mys, one from Lebyazhinka 5, and two from Khlopkov Bugor. Studies of Ancient DNA obtained from Khvalynsk and othe Eneolithic burrials in this area of the the Volga and northern Caucasus, suggest that the local population was related to the Yamnaya Peoples, but lacked the input of genetic materials from Anatolian farmers seen in the later. 

Studies based upon archaeological evidence and stable isotope analysis have suggested this population had a diet based upon the gathering of local plants, fishing, and the consumption of domestic Animals. Wilkin et al. also extracted dental calculus from two individuals from Botai in northern Kazakhstan, a site dating to about 3500 BC, where faunal remains are dominated by domestic Horses, and proteins extracted from ceramics have suggested Horses were being milked.

Map showing sites that yielded individuals with preserved ancient proteins. (a) Eneolithic, (b) Early Bronze Age and (c) Middle–Late Bronze Age sites in the Pontic–Caspian region, showing the number of individuals with a positive dairy identification out of the total number of individuals with preserved ancient proteins for each site. Strong evidence of preservation of Equine or Ruminant milk protein identifiers are depicted with black Animal icons; the single individual with equivocally identified casein peptides is shown with a grey icon. Wilkin et al. (2021).

In addition, Wilkin et al. sampled 35 Bronze Age Humans from 20 sites. These include sixteen Early Bronze Age individuals; two from Krasikovskyi 1, one from Krasnokholm 3, two from Krivyanskiy 9, two from Kutuluk 1, one from Leshchevskoe 1, one from Lopatino 1, two from Mustayevo 5, one from Nizhnaya Pavlovka, one from Panitskoe, one from Podlesnoe, one from Pyatiletka, and one from Trudovoy; as well as fourteen individuals the Middle–Late Bronze Age transition; one from Bolshekaraganskyi, two from Kalinovsky 1, three from Kamennyi Ambar 5, one from Krasikovskyi I, three from Krivyanskiy 9, one each from Lopatino 1 and Lopatino 2, one from Potapovka 1, one from Shumayevo 2, and five from Utevka 6.

Maps of all sites and individuals included in this study from the (A) Eneolithic; (B) Early Bronze Age; and (C) Middle and Late Bronze Age. Wilkin et al. (2021).

Previous archaeological isotopic studies of Early Bronze Age Yamnaya sites have suggested a diet strongly focused on herd Animals, including Cattle, Sheep and Goats. Horse remains have also been found at Early Bronze Age Yamnaya sites, but whether these were domestic Animals or wild Horses hunted for their meat is unclear. The Middle–Late Bronze Age transition was marked by an increased use of Horse-based technologies, such as chariots, which clearly indicates these people were using domestic Horses.

Fifty five of the fifty six dental calculus samples tested yielded identifiable protein data, and forty eight of those produced strong enough signals of proteins commonly found in the oral cavity that they were included in the study. 

The nineteen oldest individuals examined, all dated to between 4600 and 4000 BC, came from five Eneolithic sites close to the Volga River, or tributaries of that river, in southwestern Russia. Of these nineteen, eleven yielded good enough data to be included in the final study, with ten showing no evidence for the consumption of dairy products. The remaining individual yielded to peptides associated with Bovine α-S1-casein milk curd protein, although Wilkin et al. do not take this as absolute proof of milk consumption, as the most common dairy protein, β-lactoglobulin, was not recovered. Neither of the Botai individuals returned any evidence for dairy consumption. 

Fifteen of the sixteen Early Bronze Age individuals included in the study yielded multiple Ruminant dairy peptides including β-lactoglobulin, with some also producing α-S1 casein, α-S2-casein or both. Many of these peptides were identifiable to genus level, with the most common genera being Ovis (Sheep), Capra (Goats), and Bos (Cattle, Buffalo, Bison, and Yaks, although presumably Cattle were the most likely milk-producers). Interestingly, two individuals, both from Krivyanskiy 9, on the southwestern fringe of the study area, yielded Equus (Horse, Donkey and Kiang, although only Horses would have been present in the study area) β-lactoglobulin. These individuals were estimated to have died between 3305 and 2633 BC.

Histogram of taxonomic specificity of dairy peptide spectral matches per individual. Histograms for individuals with evidence for consumption of dairy, from the Eneolithic (a), Early Bronze Age (b) and Middle and Late Bronze Age (c). PSM, peptide spectral match. Wilson et al. (2021).

Fifteen of the nineteen Middle–Late Bronze Age transition yielded positive evidence for the consumption of Bovine milk products, including peptides from β-lactoglobulin, α-S1-casein and α-S2-casein, and the whey protein α-lactalbumin. It was possible to identify some of these peptides as being Ovis or Bos, but both Capra and Equus were absent from the sample.

Wikin et al.'s results point to a clear shift towards milk consumption between the Eneolithic and Early Bronze Age, with 10 of 11 Eneolithic individuals showing no evidence of dairy consumption, whereas 15 of 16 Early Bronze Age individuals showed such evidence. A single Eneolithic individual, from Khvalynsk, showed possible evidence of dairy consumption, but this result cannot be taken with any confidence. This strongly suggests that the widespread adoption of dairy products as part of the Human diet was associated with the Eneolithic-Early Bronze Age transition on the Pontic–Caspian Steppe. This is in contrast to the situation to the west, where settled European farmers were clearly consuming dairy products in the Eneolithic. This in turn suggests a cultural frontier between the European farmers and the Steppe herders. 

The ability of proteonomics to identify the Animals producing the milk used for Human consumption sheds light on the Animals being kept by these peoples. The Pontic–Caspian Steppe provides a rich environment capable of supporting a range of herd Animals, including Cattle, with a relatively high water-demand, and Sheep and Goats, which favour more arid conditions. Interestingly, a recent study of Early Bronze Age individuals from the steppes suggests that the persistence of lactase (the enzyme that allows digestion of whole milk) production into adulthood in these individuals was rare, but this does not rule out the production of milk-derived products such as yogurts, cheeses or fermented milk beverages.

The milking of Horses has previously been suggested for the Botai culture of Kazakhstan, but Wilkin et al. found no evidence of this (although their sample size, two individuals, was quite small). Horse milk was apparently consumed by two individuals from the Early Bronze Age of the Pontic–Caspian Steppe. These findings, combined with the discovery that the Horses of Botai were not the Domestic Horse, Equus caballus, supports the idea that Horse domestication originated on the Pontic-Caspian Steppe rather than with the peoples of Central Asia. The oldest Horse remains shown to contain genetic markers for modern domestic lineages date from between 2074 and 1625, and come from sites in Russia, Romania and Georgia. The discovery of the oldest known evidence in the Pontic-Caspian Steppe region, which also saw the first appearance of Horse-drawn chariots around 2000 BC, contributes further evidence to this hypothesis.

Wilkin et al.'s findings contribute to the growing understanding of a significant cultural and technological revolution associated with the Eneolithic-Early Bronze Age transition on the Pontic-Caspian Steppe. As well as the, obvious, adoption of bronze as a metal for making tools and weapons, this shift included the abandonment of riverine settlement sites, the appearance of kurgan cemeteries on formerly uninhabited arid plateaus, the appearance of wheeled vehicles, and the occasional placement of Horse bones in Yamnaya burials. This was accompanied by a rapid expansion of the range of these peoples, both to the west into Europe and to the east into the Altai Mountains. Wilkin et al.'s findings shed no direct light upon the role of Horses in this expansion, but evidence for the consumption of Horse milk is clearly evidence for Horse domestication, which is likely to also imply Horses were being used for other purposes. The combination of a dietsry shift to include nutritionally rich dairy products, the adoption of Animal-drawn vehicles as a means to transport greated loads, and the domestication of highly versatile Horses is likely to have significantly transformed the cultural and economic environment of the Pontic-Caspian Steppe, enabling Humans to venture into previously uninhabitable areas, and thereby access further new resources, such as seasonally snow-covered upland pastures. It is, of course, possible that all of these elements were present to some extent before the Eneolithic-Early Bronze Age transition, but that transition clearly shows the widespread adoption of all these technologies by populations over a wide geographical area.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.