Human Identity

HUMAN IDENTITY

In most biological respects, humans are like other living organisms. For instance, they are made up of cells like those of other animals, have much the same chemical composition, have organ systems and physical characteristics like many others, reproduce in a similar way, carry the same kind of genetic information system, and are part of a food web.

Fossil and molecular evidence supports the belief that the human species, no less than others, evolved from other organisms. Evidence continues to accumulate and scientists continue to debate dates and lineage, but the broad outlines of the story are generally accepted. Primates—the classification of similar organisms that includes humans, monkeys and apes, and several other kinds of mammals—began to evolve from other mammals less than 100 million years ago. Several humanlike primate species began appearing and branching about 5 million years ago, but all except one became extinct. The line that survived led to the modern human species.

Like other complex organisms, people vary in size and shape, skin color, body proportions, body hair, facial features, muscle strength, handedness, and so on. But these differences are minor compared to the internal similarity of all humans, as demonstrated by the fact that people from anywhere in the world can physically mix on the basis of reproduction, blood transfusions, and organ transplants. Humans are indeed a single species. Furthermore, as great as cultural differences between groups of people seem to be, their complex languages, technologies, and arts distinguish them from any other species.

Some other species organize themselves socially—mainly by taking on different specialized functions, such as defense, food collection, or reproduction—but they follow relatively fixed patterns that are limited by their genetic inheritance. Humans have a much greater range of social behavior—from playing card games to singing choral music, from mastering multiple languages...