The Search for Ancestors and Origins

Thinking human beings have always been fascinated with the concept of origins, and of all origins, none has been of more interest than that of humans. Human groups have asserted deeply meaningful identities by attributing their present being to a particular origin. Most of these psychologically necessary genealogies relied upon some divine agency to explain human existence. From a surprisingly early time, however, civilized humans (such as the Greeks) recognized that there

Homo sapiens Facts

Classification:

Kingdom: Animalia

Subkingdom: Metazoa

Phylum: Chordata

Subphylum: Vertebrata

Superclass: Tetrapoda

Class: Mammalia

Subclass: Theria

Infraclass: Eutheria

Order: Primates

Suborder: Anthropoidea

Superfamily: Hominoidea

Family: Hominidae

Genus and species: Homo sapiens

Geographical location: Originally Africa, now spread to all continents Habitat: Originally savannas, now spread to all habitats

Gestational period: Nine months Life span: Originally a maximum of twenty-five years; now over one hundred years, with averages from forty to eighty years, depending on habitat

Special anatomy: Large, well-developed brain; upright, bipedal posture; opposable thumbs; larynx, vocal chords, and tongue adapted to produce a wide variety of sounds for language had been a time when humankind did not know the use of metals. Subsequently, many thinkers took the concept of cultural evolution for granted.

By the seventeenth century c.E., anatomy had become a popular field of study. Comparisons soon established how like human anatomy that of the higher primates was. By the mid-eighteenth century, Carolus Linnaeus, the originator of modern biological classification, even ventured to place man and the apes within the same family. Yet this classification did not imply any necessary common ancestry. Linneaus and others of his time created the notion that individual species arose through a special, divine plan. The idea of special creation lost credibility when the fact of extinction became established at the end of the eighteenth century and as the diversity of species and varieties came increasingly to be appreciated. Nature, moreover, was no longer seen to be a benign reflection of its creator. As opinions of a distinctly human nature likewise declined, the realization that humans are animals encountered lessening resistance.

Before human evolution was generally accepted during the twentieth century, the evolution of cultures, language, law, institutions, and at least some animals had already been established. Though the idea was there, reliable evidence for the biological evolution of humans remained elusive. Before 1891, the only known prehistoric human bones belonged to Neanderthals; they were quickly and effectively dismissed as pathological freaks. Since Raymond Dart's Taung child of 1924 was likewise dismissed with ridicule, only a few specimens of what would later be recognized as Homo erectus (Java man and Peking man) survived to satisfy the now fashionable quest for a "missing link." (There are still innumerable missing links, but the essential connection between ancestral apes and man was confirmed by the discovery of australopithecines.) It was Robert Broom who, during the 1930's, established the reality of the australopithecines and, by implication, of human evolution.

Though the evolution of the hominid line is certainly a worthwhile scientific topic, it has al ways been regarded as much more than that, because the claims to ancestry define humanity. Yet the formal constraints of science are limited. In a remarkable series of thirty-nine papers (published between 1949 and 1965), for example, Raymond Dart promulgated an interpretation of the australopithecines as aggressive, predatory, and cannibalistic hunters. Because of the recurrent wars in which civilization had engaged during this period and shortly before, this image of human (or almost human) nature appealed to the popular imagination—so much so that less technical restatements of the same views by Robert Ardrey were not only commercially successful but also politically influential. Interpretations of australopithecine and early hominid behavior have subsequently changed, however—many now see these species as abject scavengers disputing the possession of already picked-over animal corpses with hyenas. It is arguable whether such changing interpretations are attributable to scientific advances or are the result of changing philosophical views of humanity.

—Dennis R. Dean See also: Apes to hominids; Convergent and divergent evolution; Evolution: Animal life; Evolution: Historical perspective; Extinction; Fossils; Genetics; Homo sapiens and human diversification; Human evolution analysis; Neanderthals; Primates.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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