29 January 2021 by Prof Nigel Bennet and Dr Daniel Hart
Prof Nigel Bennett and Dr Daniel Hart were part of an international team whose research into African mole-rats was not only published in the distinguished journal Science but made the cover.
Prof Nigel Bennett, a professor in UP’s Department of Zoology and Entomology, and post-doctoral fellow Dr Daniel Hart worked closely with the Max Delbrück Center for Molecular Medicine in Berlin, Germany on their recent research, the findings of which show that mole-rats communicate in their own dialect.
Prof Bennett occupies the Department of Science and Technology and National Research Foundation research chair in the field of mammalian behavioural ecology and physiology, and the UP Austin Roberts Chair of African Mammalogy at the Mammal Research Institute. He has explored the ecology, physiology and behaviour of African mammals, focusing on African mole-rats, and on Damaraland mole-rats in particular. Dr Daniel Hart’s research focuses on the evolutionary physiological and biomedical studies of African vertebrates.
They tell us more about their groundbreaking research.
What makes African mole-rats so interesting?
NB: African mole-rats exhibit a broad spectrum of sociality, with some species being strictly solitary and others such as the naked mole-rat exhibiting a social structure similar to eusocial insects. As a consequence of this broad spectrum, with some species being strictly solitary to others being eusocial, they can be used as a model family to unravel the factors that have promoted true sociality or eusociality in these underground rodents.
DH: They are great models to show how animals adapt to their environment. For example, their broad spectrum of sociality has been brought about by the different species inhabiting different climatic regions. Simultaneously, their incredible ability to withstand hypoxic (low oxygen) conditions has come about because of their exclusive subterranean lifestyle.
What made you focus your research on them?
NB: I first became interested in mole-rats because they live underground and nobody had studied the various South African species in any detail. So I concentrated on finding out the different reproductive strategies they have. For example, solitary species come together only to mate and after much research we found that they break down xenophobic barriers through seismic signalling by drumming with the hind feet. In the social species there is a distinct breeding female and several breeding males – where reproductive inhibition in non-breeders is brought about by incest avoidance. In the two eusocial or truly social species the non-breeders are inhibited from breeding by social suppression by the breeding female. This is currently being investigated.
DH: When I began my research career, a wise mentor gave me a piece of advice: study animals that you can ask interesting questions about. So far, I have not found an animal that you can ask more interesting questions about than African mole-rats – the number of exciting questions and answers that mole-rats have to offer drew me to studying them.
How does their social and communication habits have an impact on how we understand them?
NB: The social and communication skills of human beings and naked mole-rats appear to have much more in common than anyone might have previously thought. Naked mole-rats have a linguistic culture that developed long before human beings even existed.
DH: Naked mole-rats live in large families (50 to 60 individuals), with some colonies reaching 300, controlled by one female, the queen. Each colony member has its own “job”, and everyone recognises their own colony and family members, even in the dark. Even after the vast number of studies on these amazing animals, how the colony structure is maintained has somewhat eluded us. But, like humans, it may come down to dialects to some extent. From this study, we have learnt that each mole-rat colony has its own dialect, dictated by the queen, allowing colony cohesion and detection of intruders. Interestingly, this dialect can be learnt, which is an uncommon ability in most animals. This new understanding brings us closer to figuring out how these large families work together and stay together. This understanding can possibly help us in furthering our knowledge about human dialects.
Are there any other animals that provide as interesting an array of applications as the mole-rat?
NB: African mole-rats really are unique in that we are finding out more about how they are able to tolerate low oxygen concentrations and high carbon dioxide concentrations in the nests of their burrow systems. Also, mole-rats have enabled us to find out how speciation has arisen within the family Bathyergidae in Africa as a result of rifting and the development of the major river systems in Africa. Currently, we do not know of any group of animals that has so many interesting questions that have human applications.
DH: We are fortunate, as Africa has a treasure trove of unique animals with remarkable features and abilities. One such animal we are working on is the tenrec, which is a fantastic model of a prehistoric mammal. With these animals, we hope to peer back in time to unravel essential questions about evolution. Like the mole-rats, they also possess remarkable physiological and molecular traits, which could be vital to biomedical studies.
What do you do in your spare time?
NB: I like to explore different countries in Africa; I have a particular fondness for the mountain gorillas and eastern lowland gorillas in the forests of Rwanda, Uganda and the Democratic Republic of the Congo. When I can afford to, I go to see these amazing animals, and it gives me a great deal of pleasure to be able to explore these amazing forests in Africa that are still pristine and protected from logging.
DH: I have quite a big interest in other scientific subjects, namely astrophysics, astronomy and cosmology. I also enjoy listening to books or podcasts on these subjects and reading articles when I get a chance. Also, I am passionate about sport, so I enjoy catching up on the world’s sporting events when I can.