Archive for May, 2014

Human Evolution and the Birth of Medicine

Thursday, May 29th, 2014

There is no discussion: human and apes are close relatives with a common ancestor. Evolution studies confirm this hypothesis with different fossils differing in age with traces of genomic DNA and molecular features between these two species. Social science in apes also tells us that they are always in groups, have a structure of hierarchy and respect such as human societies. However, some questions remain, such as how primates deal with diseases and pain. In many traditional societies around the world people are very dependent in plants for both food and medicine. Close to a century ago, for example, a Tanzanian medicine man, Babu Kalunde, discovered an important treatment that saved the lives of many people in his village, who were suffering an epidemic of a dysentery-like illness. He learned about the potential medicinal value of a plant known as mulengelele by observing a sick animal eat the roots of the plant. This is a fact: animals in the jungle have to learn about medical plants and how to self-medicate. And this feature passes from generation to generation with parents teaching youngsters what to eat when they feel specific types of pain. Most of the details about two types of self-medicative behaviorin the great apes – namely, bitter-pith chewing and leaf swallowing – come from three study sites, Mahale and Gombe inTanzania and Kibale in Uganda, although these behaviors have been documented from 10 additional sites across Africa. The geographical, ecological, and climatic variation of these sites is great, ranging from low-elevation, moist tropical forest and woodland to forest. Such wide variation in geography, ecology, and climate where leaf swallowing and bitter-pith chewing are known to occur suggests that great ape populations elsewhere on the continent might also engage in these behaviors (for more information see “Self-Medicative Behavior in the African Great Apes: An Evolutionary Perspective into the Origins of Human Traditional Medicine” by Michael A. Huffman). Primates generally self-medicate with plants in the jungle and teach others what to eat depending on the pain. Specific plants for stomach pain are always shown to members of the community and offspring. The strong similarities in plant selection criteria among the African great apes in response to parasite infection and gastrointestinal upset, and the common use of some plants by chimpanzees and humans to treat such illnesses, are tantalizing evidence for the birth and evolution of medicine. Our earliest hominid ancestors may have exhibited some similarities in plant selection criteria with both extant apes and modern humans. Although the fossil record provides no direct evidence concerning specific feeding behavior and diet, it seems reasonable to hypothesize that early hominids would have displayed at least the range of extant ape self-medicative behavior. It appears that the fundamentals of perceiving the medicinal properties of a plant by its taste, smell, and texture have their roots deep in our primate history. A major turning point in the evolution of medicine is likely to have been the advent of language in early humans, which enabled people to share and pass on detailed experiences about plant properties and their effects against disease. That probably was the birth of medicine on earth. Since then, medicine continues to evolve, but if we go back to the jungle, primates use the same medical plants for generations to treat different types of pain. I believe we can learn a lot from them, especially to accelerate the development of new drugs for specific diseases. The bottom line is that primates are smarter than we think…