The Uniqueness of Humans and an Anthropological Perspective, Exams of Anthropology

Download The Uniqueness of Humans and an Anthropological Perspective and more Exams Anthropology in PDF only on Docsity! 229JMAJ, July /August 2011 — Vol. 54, No. 4 The Uniqueness of Humans and an Anthropological Perspective JMAJ 54(4): 229–233, 2011 Mariko HASEGAWA*1 Key words Human evolution, Childhood, Communal breeding, Triadic representation, Language *1 Professor, Department of Evolutionary Studies of Biosystems, the Graduate University for Advanced Studies, Kanagawa, Japan (hasegawamk@soken.ac.jp). This article is a revised English version of a paper originally published in the Journal of the Japan Medical Association (Vol.139, No.4, 2010, pages 886–890). The original paper is based on a lecture presented at Fiscal Year 2009 Maternal and Child Health Seminar “Toward the Realization of the Japan Medical Association Child Support Declaration IV” held at the JMA Hall on February 21, 2010. Introduction Although I majored in physical anthropology during my undergraduate and graduate studies, the focus of my academic interest was not human beings. I studied the behavior of wild chimpan- zees in Africa during my years at the anthro- pology department because I wanted to explore virgin territories and observe wildlife in its natu- ral state. Later, I studied deer, sheep, peacocks, etc., and only after that did my interest eventually turn to human beings. This was because the study of various animal species instilled in me a renewed understanding of the peculiarity of humans as a strange species, and also because I felt a sense of responsibility as an anthropologist to study the evolution of the human species. Human beings are animals that belong to the primate order among mammals. Humans’ closest relatives are chimpanzees, whose ances- tors branched from ours and started to follow a different path about 6 million years ago. Chim- panzees and other apes have since remained in tropical rain forests, and are now on the brink of extinction. On the other hand, after the human race experienced the emergence and extinction of several species, Homo sapiens that evolved about 200,000 years ago spread all over the earth and prospered to reach today’s population of 6.8 billion. Despite the sharing of a common ancestry until 6 million years ago, chimpanzees remain in an ecological position similar to that of many other mammalian species, while humans have accomplished an “unnatural” success that may even endanger the global environment. Actually, no other animal species have caused such drastic alteration to the planet’s surface in such short time, driven many other species to extinction, developed science, and deliberated about their condition. What have been the keys to the achievement of this ability? Anthropology is the study of the evolutionary history of humanity. It is often regarded as the study of the past records of human evolution, such as fossils. Although this in itself is interest- ing, anthropology has been accumulating a large body of data on the history and culture of humans as a species in physical anthropology, involving genetics, endocrinology, ecology, evolutionary biology, and paleoenvironmental science, as well as in combination with humanity and social sci- ences, such as prehistory, cultural anthropology, and ethnography. The essence of science lies in the explanation of the present reality and the prediction of the future. This being the case, anthropology as the science of human evolutionary history should be able to explain not only past evolutionary history but also the present reality of our life and predict some aspects of humanity’s future. My interest in this approach developed slowly, and grew into a Conferences and Lectures 2009 Maternal and Child Health Seminar 230 JMAJ, July /August 2011 — Vol. 54, No. 4 Hasegawa M sense of responsibility to make it happen. In this article, I consider the present and future of humanity, based on the findings from recent studies. A Brief History of Human Evolution The human race is defined as “habitually erect bipedal primates.” All living and extinct habi- tually erect bipedal primates are called hominins. Genetic analyses suggest that the lineage of chimpanzees and that of hominins branched about 6 million years ago, and fossil evidence also supports this estimation, as the fossils of Sahelanthropus, unearthed recently in the Afri- can country of Chad, date back to about 6 million years ago. Various species subsequently emerged within the hominins. All but one of them have become extinct, leaving us Homo sapiens as the only surviving species of hominins. The reason why hominins adopted bipedalism is still unknown, although several theories have been proposed. Sahelanthropus that lived 6 million years ago, as well as Ardipithecus and Australopithecus that followed, did not live exclusively in the savannas but depended partly on forests, and were adept at tree climbing. The evolutionary reason why they started to walk erect 6 million years ago, when they still lived in forests, remains unknown. The life of the hominins in savannas began in earnest after the evolution of early Homo species about 2 million years ago. The remains of Homo ergaster dating back to about 1.6 million years ago provide representative fossil evidence. After that time, the human body began to resemble the proportions of modern humans, their feet and legs changed shape, and they were no longer adept at tree climbing. About the same time, they lost most of their body hair, and supposedly replaced it with numerous sweat glands instead. The body of Homo species adapted specifically to long treks in the hot African savannas. About that time, a hominin species resembling Homo ergaster moved out of Africa and spread to the Eurasian continent. This was Homo erectus. After persisting for about one million years, they became extinct. Another hominin species then emerged about 500,000 years ago. Having larger brains than H. erectus, they are sometimes referred to as “archaic sapiens.” Nean- derthals were part of this group, but they also became extinct. We Homo sapiens emerged about 200,000 years ago in Africa, and then spread rapidly throughout the world. All people living in the world today are members of this species that originated in Africa. Large Brains, Cognitive Abilities, and Language A factor directly supporting the prosperity of humans all over the planet is civilization based on science and technology. While humans developed various technologies before the birth of science, scientific elucidation and technological progress have now become inseparably linked. These have been altering the world, making our lives safer and more comfortable, and reducing death rates. Scientific-technological civilization was made possible by the abilities of the human brain to process elaborate information and communicate verbally. Humans were able to develop science fundamentally because of their sophisticated cognitive abilities. These include the abilities in abstraction, categorization, reasoning of causali- ties, application of knowledge to novel situations, and many other areas. Rudimentary develop- ment of these abilities is also seen in chimpan- zees, which are humans’ closest relatives among the primates. These abilities did not develop suddenly after the emergence of the hominins. However, they were brought into full play in humans because of the acquisition of language. Chimpanzees also have some abstraction and categorization abilities and can perform reason- ing to some degree. However, the presence of language dramatically enhances thinking, as it enables us to label objects, events, and concepts in definite terms and to have mental representa- tions of them. Then, what is the biological basis for lan- guage? Why did it evolve only in the lineage of humanity and not in that of other primates such as chimpanzees? To answer these questions, we need to investigate the uniqueness of humans, combining the knowledge from various fields of human study, including brain neuroscience, anthropology, prehistoric archaeology, ethnology, ecology, and psychology. To begin with, the order of primates is a taxon characterized by larger brains in comparison with other mammals. Primates live in partially closed, permanent groups. The members of the