Bonobo diet of aquatic greens may hold clues to human evolution

By: Thomas Schmitt Attorney on July 01, 2019 / comment : 0 Anthropology, Congo, Human Evolution, Wildlife

Observations of bonobos in the Congo basin foraging in swamps for aquatic herbs rich in iodine, a critical nutrient for brain development and higher cognitive abilities, may explain how the nutritional needs of prehistoric humans in the region were met. This is the first report of iodine consumption by a nonhuman primate and it is published in the open access journal BMC Zoology.

Credit: Zana Clay, LuiKotale Bonobo Project

Dr. Gottfried Hohmann, from the Max Planck Institute for Evolutionary Anthropology, the lead author of the study said: "Our results have implications for our understanding of the immigration of prehistoric human populations into the Congo basin. Bonobos as a species can be expected to have similar iodine requirements to humans, so our study offers - for the first time - a possible answer on how pre-industrial human migrants may have survived in the Congo basin without artificial supplementation of iodine."

The researchers made behavioural observations of two bonobo communities in the LuiKotale forest in Salonga National Park, Democratic Republic of Congo. These observations were combined with data on the iodine content of plants eaten by bonobos from an ongoing study by the Leibniz Institute for Zoo and Wildlife Research, Berlin. They found that the aquatic herbs consumed by bonobos are a surprisingly rich natural source of iodine in the Congo basin, a region that was previously thought to be scarce in iodine sources.

Dr. Hohmann said: "Evolutionary scenarios suggest that major developments of human evolution are associated with living in coastal areas, which offer a diet that triggered brain development in hominins. The results of our study suggest that consumption of aquatic herbs from swamps in forest habitat could have contributed to satisfying the iodine requirements of hominin populations used to diets prevalent in coastal environments."

He added: "Our report potentially answers the question of how apes obtain iodine from natural food sources, when many populations inhabit areas considered to be iodine deficient. Other apes such as chimpanzees and gorillas have also been observed eating aquatic herbs, which suggests that they could be obtaining essential iodine from these sources."

The authors caution that without data on the iodine status of wild bonobos, it is difficult to tell how much iodine they absorb, although given the high concentrations in the herbs, it is likely to be substantial. The authors also stress that the iodine concentrations obtained at the field site of LuiKotale may not be reflective of the entire Congo basin.

Source: BioMed Central [July 01, 2019]

Scientific study reveals the enigmas on social behaviour of western lowland gorillas

By: Thomas Schmitt Attorney on February 06, 2019 / comment : 0 Anthropology, Congo, Genetics, Society, Wildlife

A new study published in the journal Proceedings of the Royal Society B: Biological Sciences reveals one of the enigmas related to the social behaviour of the western lowland gorilla (Gorilla gorilla gorilla) in the heart of the African equatorial rainforest. These primates show a dynamic social structure - individuals change frequently between families - with a high degree of tolerance and peaceful coexistence among the members, according to the new article which counts on the participation of the experts José Domingo Rodríguez Teijeiro, Magdalena Bermejo, Guillem Molina-Vacas, from the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio).

The social behaviour of the western lowland gorilla can impact the transmission of diseases  in this endangered species [Credit: Germán Illera]

According to the authors, this social behaviour may have played an important role in the evolutionary story of the species, easing the exchange of information and a better exploitation of trophic resources. However, this social dynamics may have worsened the impact of some infectious diseases in the population of gorillas, experts warn. In this context, epidemic Ebola virus outbreaks, which affected the primate population in Congo between 2002 and 2004, caused the disappearance of 95 % of this ape, causing this species to be in critical danger of extinction according to the Red List of threatened species by the International Union for the Conservation of Nature (IUCN).

In the new study, carried out in the Ngaga Forest in the Republic of the Congo, counts on the participation of German Illera (Great Apes Conservation/Research Odzala-Lossi and SPAC gGmbH, Republic of the Congo), Giovanni Forcina, Rubén Bernardo-Madrid, Eloy Revilla and Carles Vilà (Doñana Biological Station EBD-CSIC) and other experts of the University of Rennes (France).

After the western lowland gorillas in the heart of the forest

The ecology and behaviour of the western lowland gorilla inside the equatorial forests was an enigma so far. Since the first scientific studies started, differences between the behaviour of these two African primates were known: the western lowland gorilla (Gorilla gorilla gorilla) -living in rainforests around the basin of the River Congo- and the mountain gorilla (Gorilla gorilla beringei), a better studied primate in the volcanic mountainsides of the African Rift. At the moment, hunting and epidemics endanger the survival of wild populations of these primates which share more than 98% of genetic material with the human species.

Unlike the mountain gorilla, which has aggressive and infrequent interactions between families, the western lowland gorilla was known to have frequent and peaceful interaction between members of the families. However, due a low visibility inside the forests, western lowland gorillas that had been studied in bais, typical open clearings which are the meeting point for families of the species to feed from plants rich in mineral salts.

As part of the study, the experts conducted a scientific monitoring over five years to three families of the western lowland gorilla in the same heart of the Congo forest. According to the conclusions, interaction between individuals from different families is common and peaceful so the individuals eat and play together with no signs of aggression.

Regarding methodology, experts profiled an image of the social structure and parentage relations of more than 120 gorillas through the genetic analysis of faeces samples taken over four months -in families and single individuals- in the Ngaga forest.

A dynamic social structure with no records of infanticides

Data show families have a dynamic social structure in which individuals conduct frequent changes among family groups. Young individuals are usually outside the family and enter temporarily other family groups in which they have no close relatives. This social behaviour could be linked to the lack of infanticide records in this species, experts note.

This new study shows the image of a modular society featured by the existence of strong ties which do not avoid the transfer of individuals between different families and a high degree of tolerance between their members. The results of this study show the importance of complementing in situ monitoring studies with non-invasive genetic analysis to find the structure and social dynamics in animal species which are hard to have access to. At the same time, conclusions highlight the importance of social behaviour in disease transmission and the development of effective conservation strategies in the long run.

Source: University of Barcelona [February 06, 2019]