Interpreting Evidence

Interpreting Evidence

The Copernican revolution, which had its beginning in 1543, represents a case study of how intuitive knowledge is ultimately replaced by scientific empiricism to produce a new theory of nature. From the time of Ptolemy, observations that planets, stars, sun, and moon traverse the day and night skies led to the misconception that these heavenly bodies circled a stationary earth. However, planetary orbits tabulated by Copernicus indicated that in actuality planets revolved around the sun. Known as the solar system, this understanding of nature was resisted for over a century as astronomers grappled with a succession of empirical observations by Tycho Brahe (1577), Galileo (1610), Newton (1687), and others who ultimately established the solar system as scientific fact.

The curious match between North and South America's continental outline and that of Europe and Africa caused comparable conflicting conclusions. A 1915 textbook written by Alfred Wegener examined fossil strata and living species on both sides of the Atlantic. Noting the strong similarities between them, he proposed a compelling view of geology called continental drift suggesting that these continents were adjoined in the distant past. Prominent geologists of the time argued that a geologic force capable of heaving about huge land masses did not exist. They brushed off the outlines’ similarities as mere coincidence. These scientists hypothesized that in the past continents were linked together by long land bridges that allowed species to march across oceans and populate distant shores.

A half-century later, global seafloor maps revealed a striking pattern. New crust was forming and causing the seafloor to spread; the continents were in motion. In the mid-Atlantic, for example, the continental plates that once joined North and South America to Europe and Africa were being pushed apart. When these moving plates collided with other plates, at subduction zones, one slid under the other to form high-mountain ridges like the Andes and the Himalayas. Patterns frozen in the earth's crust established the science of plate tectonics.

Why would the Copernican revolution and plate tectonics be relevant to the field of anthropology? These scientific advances are a result of empirical data that challenged and replaced the intuitive views of nature espoused by older theories. Paleoanthropology, the field devoted to understanding the process of human evolution, is based on the intuitive assumption that human intelligence and the relatively large human brain are the result of evolutionary activities that took place at the ground. This article compares the terrestrial view with a new empirical interpretation of fossil, behavioral, anatomical, and archaeological evidence that indicates climbing activities must have had a profound influence on the evolutionary increase in human-brain size.