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Fight for pristine wilderness

ANTARCTICA HAS SEEN accelerated human activity over the past few years. The impact of this has been quantified for the first time by a team of researchers led by Monash University, including Dr Bernard Coetzee from the Global Change Institute at Wits. Using a data set of 2.7 million human activity records, the team showed just how extensive human use of Antarctica has been over the past 200 years. The research was published in the journal Nature.

“We mapped 2.7 million human activity records from 1819 to 2018 across the Antarctic continent to assess the extent of wilderness areas remaining and its overlap with the continent’s biodiversity,” says Coetzee, who is based in Skukuza in the Kruger National Park. He helped conceptualise the study and collated a spatial database from multiple sources to map the extent of human activity in Antartica.

High human impact areas, for example some areas where people build research stations or visit for tourism, often overlap with areas important for biodiversity. Further the study found that only 16% of the continent’s Important Bird Areas fall within its Specially Protected Area network. The work, delivered by a transdisciplinary team of researchers from Australia, the Netherlands, New Zealand, and South Africa, will be crucial in informing measures to secure Antarctica’s wilderness.

Love at sunset

MALARIA AFFECTS OVER 228 million people annually causing over 400 000 deaths, predominantly in Africa and mainly in pregnant women and children under five.

The findings from a recent study by scientists at the Wits Research Institute for Malaria (WRIM), Stockholm University (Sweden), the Institute of Ecology, Nature Research Centre (Lithuania), and the Eijkman Institute for Molecular Biology (Indonesia) published in Nature Ecology & Evolution have implications for controlling mosquito reproduction.

For the first time, scientists have identified male mosquito-specific pheromones (odours) that influence mating rituals. The study found that males from the malaria vector species of Anopheles arabiensis and An. gambiae release pheromones that attract individual females to the swarms and increase their mating success.

“A female mosquito mates only once in her lifetime. This mating takes place with the males in a mating swarm. These dancing male mosquitoes gather in large mating swarms during dusk and dawn,” says Jacek W Zawada, co-author of the study and PhD candidate in the WRIM. “But we know very little about what stimulates swarm formation.”

Co-author and co-director of WRIM, Professor Lizette Koekemoer (PhD 1999), says manipulating such pheromones could increase the efficacy of malaria-vector control programmes. “The more we understand about how these mosquitoes reproduce and thereby increase their potential and capacity to transmit malaria, the better equipped we are to combat the disease.”

Eco-engineers in danger

AARDVARKS (ORYCTEROPUS AFER) occur across most of sub-Saharan Africa and seeing them is a delight for many wildlife enthusiasts. They are nocturnal, solitary animals who live in burrows and use their spade-like claws to dig up ants and termites on which they feed.

A group of researchers from the Wildlife Conservation Physiology laboratory at the University of the Witwatersrand studying aardvarks living in Tswalu, a reserve in the Kalahari, has found a shift in behaviour of this secretive animal from night-time to increased activity during the day.

Dr Nora Weyer (PhD 2018), who was part of the team of researchers, followed aardvarks as part of her PhD research over three years using bio loggers to record their body temperature. Assisted by satellite imaging that showed how droughts affected the vegetation, Weyer was able to connect changes in aardvark behaviour and body temperature to what was happening in the aardvarks’ environment.

Weyer’s research confirmed earlier findings by the team that there are times when the aardvarks switched their feeding. For the first time it showed that drought caused a change in behaviour. The results were published in Frontiers in Physiology.

“Aardvarks have coped with the Kalahari’s harsh environment in the past, but it is getting hotter and drier, and the current and future changes to our climate might be too much for the aardvarks to bear,” says Weyer.

By shifting their activity from the cold nights to the warm days during dry winter months, aardvarks can save some of the energy needed to keep their body temperatures up. But those energy savings were not enough to see the aardvarks through a particularly bad drought in which many aardvarks died.

Disappearance of aardvarks from the Kalahari would be devastating for many other animals in this ecosystem. The large burrows which aardvarks build provide important shelters for many other species that cannot dig their own burrows, earning the aardvark the title of “ecosystem engineer”.

Oldest bed rocked

WHILE EXCAVATING IN the Border Cave, in the Lebombo Mountains of KwaZulu-Natal near Eswatini, alumna Professor Lyn Wadley (PhD 1987) and her team discovered remnants of what they believe to be prehistoric bedding used by the inhabitants of the cave nearly 200 000 years ago. The findings were announced in the journal Science in August. The cave is a deep gash in the cliff face, sheltered from the elements, and has preserved plant material that proved invaluable to researchers.

Professor Wadley says she noticed white flecks in the brown earth of the sediment she was digging and realised they were plant traces. She removed the small chunks of sediment and stabilised them in little “jackets” of gypsum plaster. She identified the plant matter under the microscope as belonging to the Panicoideae family of grasses that grow the area. The amount of grass found suggests people brought it into the cave intentionally.

“We speculate that laying grass bedding on ash was a deliberate strategy, not only to create a dirt-free, insulated base for the bedding, but also to repel crawling insects,” says Professor Wadley.

Several cultures have used ash as an insect repellent because insects cannot easily move through fine powder. Ash blocks insects’ breathing and biting apparatus, and eventually dehydrates them. Tarchonanthus (camphor bush) remains were identified on the top of the grass from the oldest bedding in the cave. This plant is still used to deter insects in rural parts of East Africa. Professor Wadley says repeated layers of ash and plant material suggest humans deliberately laid bedding over ash.

The researchers found two teeth in the same soil layer as the bedding remnants. They dated the teeth to 200 000 years ago and surmised the bedding was from the same period. The researchers speculate these remnants may be the oldest bedding ever found. The previous record was 77 000-year-old plant bedding found in 2010 in the Sibudu Cave in KwaZulu-Natal.

Hunt for the best shot

RESEARCHERS AROUND THE world are racing to develop a vaccine against COVID-19, with more than 170 candidate vaccines now tracked by the World Health Organization. What normally takes years to produce, scientists are hoping to develop within 12 to 18 months. Wits alumni are central to three international trials of vaccine candidates in South Africa.

Professor Shabir Madhi (MBBCh 1990, MMed 1999, PhD 2004), Professor in Vaccinology and Dean of Wits Faculty of Health Sciences from 2021, is the lead researcher in the Oxford Vaccine (ChAdOx1-Cov19) trial launched in June in collaboration with the Jenner Institute at Oxford University. The vaccine is made from a weakened and non-replicating version of a common cold virus (adenovirus). It has been engineered to express the SARS-CoV-2 spike protein. The study enrolled 1970 adult volunteers aged 18-65 as well as 50 people living with HIV. The random grouping of participants received either the vaccine or the placebo. The trial will help researchers understand participants’ response to the vaccine, its safety, and whether the vaccine protects against COVID-19. This is a double-blind study, meaning neither participants nor investigators will know until the end of the trial whether the participants received the vaccine or the control. Oxford entered an agreement with AstraZeneca, a biopharmaceutical company, for further clinical development and future manufacturing.

Professor Madhi is also leading the way with the Novavax vaccine candidate called NVX-CoV2373, which was announced in August and funded by the Bill and Melinda Gates Foundation. It is engineered from the genetic sequence of SARS-CoV-2, the virus that causes COVID-19 disease.

This is a Phase 2 study which involves up to 2094 volunteers aged 18-64 to evaluate the vaccine’s safety, immunogenicity and efficacy. This trial uses technology that has successfully been used to develop vaccines against influenza and experimental Ebola and Respiratory Syncytial Virus (RSV). This is a randomised, observer-blinded, placebo-controlled trial.

Professor Glenda Gray (MBBCh 1986), president and CEO of the South African Medical Research Council, is principal investigator with Professor Linda- Gail Bekker, the COO of the Desmond Tutu Health Foundation, on a product called Johnson & Johnson Ad26.COV2-S. It is the first Phase 3 trial conducted in South Africa and started in September. As with the Oxford and the Novavax trial it will determine the efficacy of this vaccine candidate, made from the adenovirus. Professor Gray says 60 000 people are expected to be enrolled in the Johnson & Johnson trial in the United States, Mexico, Brazil, Argentina and Peru. Research from the pre-clinical studies, published in the journal Nature on 30 July, showed a single dose of the vaccine protected non-human primates against the COVID-19 virus.

Over a period of 11 years, Dr Malose Langa, Associate Professor at the Department of Psychology at Wits, tracked a group of 32 boys from Alexandra, one of Johannesburg’s largest townships, at a crucial time when they were negotiating adolescence and manhood. Although studies about black men are not new, many tend to associate young black men with gangs, crime and violence. Dr Langa’s study found evidence which runs counter to this. His research, also published in a book Becoming Men (Wits University Press), reveals stories of ambition, aspiration to achieve and career goals to break out of the cycle of poverty. It provides rich personal stories of how some young black men are living out alternative versions of masculinity. The research is essential reading for those working with adolescents and suggests services and interventions to support them.

Stop the bulge before pregnancy

TWO THIRDS OF South African women are overweight or obese. One in four adults die prematurely (before the age of 70) from cardiovascular disease, diabetes, cancer or chronic respiratory disease. Among women living in Soweto, one in 10 will be diagnosed with gestational diabetes during pregnancy. Half of them will go on to develop diabetes within the next 10 years. Their babies are three times more likely to become obese themselves.

But little is known about how diet during pregnancy influences growth in the womb, particularly in communities where obesity rates are high. Dr Stephanie Wrottesley (PhD 2018), a postdoctoral researcher at the Wits Developmental Pathways for Health Research Unit, conducted a study of women with Professor Pedro Pisa and Professor Shane Norris (BSc Hons 1997) and recorded their dietary patterns during pregnancy.

The researchers found that there were positive effects from an improved diet during pregnancy. But these benefits were most obvious in women whose weight was normal at the start of their pregnancies. This suggests that improvements made to the diets of overweight and obese women once they are pregnant may have a limited impact on their health – and that of their babies.

Bone arrowhead shows big thinking

BOW AND ARROW technology gives hunters a unique advantage over their prey. It allows them to hunt from a distance, and from a concealed position.

This kind of technology requires a high degree of cognitive flexibility.

Until now, evidence for bow hunting technology using bone and dating back more than 60 000 years has only been reported from South Africa’s KwaZulu-Natal region. Now an in-depth study of a bone arrowhead found in the Eastern Cape extends the known distribution of this technology farther south – and slightly earlier than previously thought. The study, published in Quaternary Science Reviews, focused on a long, thin, delicately made, pointed bone artefact. It was conducted by Dr Justine Bradfield, a senior lecturer at the University of Johannesburg, Dr Jerome Reynard (MSc 2012, PhD 2016), lecturer in Osteoarchaeology at Wits, Professor Sarah Wurz from the School of Geography, Archaeology and Environmental Studies at Wits, and Professor Marlize Lombard from the Palaeo-Research Institute at the University of Johannesburg.

The bone artefact was found at the Klasies River main site, along the Eastern Cape coast, which comes from deposits dated to more than 60 000 years ago. It closely resembles thousands of bone arrowheads used by the indigenous San hunter-gatherers from the 18th to the 20th centuries.

The study shows that the pointed bone artefact from Klasies River was hafted, maybe dipped in poison, and used in a manner similar to identical bone points from more recent contexts. It fits in with what is known of ancient people’s cognition and abilities in southern Africa.