Homo sapiens

Exemplar: Cro Magnon 1 [Les Eyzies, France] - c.30,000 y.a.

And so we come to the last step in the story, humans as we are, HOMO SAPIENS. Our ancestors seem to have appeared out of some regional subpopulation of Homo heidelbergensis over 130,000 years ago, most likely in the Kenya-Tanzania area of Africa.

In sapiens the face is markedly shrunken in relation to the brain, which attains an adult size of 1040cc to 1595cc. The forehead rises sharply, browridges are very small or absent, and the chin is prominent. The skeleton is very gracile; bones are lighter and smoother, without any loss in body size. On average, males stand 1.7 to 1.8 meters and weigh 65 kilos; females stand 1.5 to 1.6 meters and weigh 54 kilos.

Compared to the Neandertal skull, modern humans (shown in a Cro-Magnon exemplar) look almost infantile. The cranium seems vulnerably round and delicate. These "juvenile" features arise through an evolutionary process called neoteny, in which evolution creates new characteristics by delaying developmental trends leading to the adult form. Adults appear more childlike, and also require a longer period of developmental parenting. This in turn raises the importance of child socialization and cultural transmission on adult behavior. Longer and stronger parent-child bonds, schooling, and the cultural consequences of education arise as new evolutionary forces.

From their origins in eastern Africa modern humans, in the last great human migration known, moved north into the Middle East, Europe, southern Asia, and finally into every region of the world. About 40,000 years ago, with the appearance of Cro-Magnon culture, the sophisticated Upper Paleolithic tool industry flourished in Europe. Humans used a wider range of raw materials (such as bone and antler) shaped into a wider and more elegant variety of implements for making clothing, tools, habitats, art and ornamentation. Fine artwork appeared over the next 20,000 years in the form of decorated tools, oil lamps, beads, ivory carvings of humans and animals, clay figurines, musical instruments, and spectacular cave paintings.

The extreme reduction in size of the jaw across human evolution, along with its corresponding shift under the skull, has had an impact on human dentation -- particularly in the frequency with which humans show irregular or misaligned teeth. A beautiful, regular smile is the result of a delicate balance among many different facial genes. And so a regular smile is the signal of good genes that some theorists claim is the underlying sexual significance of physical beauty.

Even within the last 50,000 years, a trend toward smaller teeth and bone mass is apparent. The face, jaw and teeth of Mesolithic humans of 10,000 years ago were about 10% more robust than those of modern humans; Upper Paleolithic humans of about 30,000 years ago were about 20 to 30% more robust. Even among modern humans, the smallest tooth sizes are found in those areas where food processing techniques have been used for the longest time. Thus, right up to the present, evolution has continued to adapt humans to their ever-changing technological environment.