Earth Science: Evolution – Homo Sapiens
Modern humans first appeared in East Africa around 200,000 years ago. From there they spread out to Europe, Asia, Australia, and America, and initially existed side-by-side with other hominina—until only they remained.
Homo sapiens (Latin for “wise man” or “knowing man”) are today the only surviving species of the genus Homo and have the most highly developed brains of all living beings. With a volumetric mass of about 85.4 cubic inches (1,400 cm3), Homo sapiens’ brains are twice as large as those of Homo habilis.
This volume increase was achieved in an evolution aryperiod of only two million years. It has given modern humans mental capabilities that have enabled them to recognize and deliberately change the world around them. The increase in brain volume is principally due to folding and surface enlargement of the cerebral cortex
Scientists consider this a side effect of the extended development period in human children. At birth, human brain capacity is only about 25 percent of its full potential, which requires substantial post-birth development of the brain. Perception of the external world using the eyes and ears, as well as the olfactory and tactile senses, strongly stimulates the formation of new brain cell linkages. During this extended period, the child is dependent on the care of adults. Therefore this phase is also a prerequisite for structuring relationships and social behavior.
The complete unfolding of the mental capacities of humans only became possible with the acquisition of language. Scientists assume that the linguistic capabilities of humans developed alongside their ability to use tools. This facilitated a cultural evolution, with progress that is unique in the animal kingdom, encompassing the processes characteristic of humans: perception, recognition, thinking, remembering, learning, and communicating about these experiences.
At around 5000 to 4000 B.C., oral communication was supplemented by writing, the conveyance of information via a system of signs that had a clearly defined meaning. At that time, and independently of one another, different types of writing developed in various advanced civilizations. Probably the oldest written documents come from Mesopotamia.
VOICE AND LANGUAGE
Voice and language serve human communication. The production of complex sounds requires an anatomically complex voice apparatus. In order to produce a spectrum of sounds, the cartilaginous larynx housing the vocal cords is located low in the throat.
Other prerequisites are a sufficiently mobile tongue, a closed row of teeth and a highly arched roof of the mouth. Appropriate changes of the brain supported a refined control of lips and tongue; however, why and when these changes occurred is still unknown.
BASICS
EDWARD SAPIR, a German-American ethnologist and linguist, noted that language is an exclusively human, non-instinctive method for conveying thoughts, feelings, and desires by means of a system of freely created symbols.