|Themes > Science > Life Sciences > Human Races > The Races of Humanity|
The human species is blessed with great variety and diversity. Its rich diversity resulted from its global distribution, which caused the different populations of humanity to be geographically separated and thus reproductively isolated. Reproductive isolation enabled divergence -- the process of divergent evolution -- to occur, causing the isolated populations to evolve in different directions, developing their own distinct ensembles of genetic traits and characteristics.
Divergent evolution is the process by which new life forms are created by the division and separation of life into different branches. Human evolution has seen its share of divergent branching. The generic name commonly used to refer to the genetically different populations, branches or divisions of humanity -- that share both a common biological ancestry and an ensemble of unique, genetically transmitted traits and characteristics which distinguish them from other populations -- is "race." But in the human species, as in any species enjoying a great degree of variety, the constant branching and dividing that characterizes the process of divergent evolution has created many different levels of branches and divisions, each of which possesses genetic traits which distinguish it from other branches or divisions at the same level. For purposes of taxonomic accuracy each of these levels should have its own specific name and definition. The first or highest level is called the species, and it is simply and objectively defined as including all those populations which are capable of interbreeding with each other and producing fully fertile offspring, and which do in fact interbreed under conditions of close and extensive contact. The term race is commonly used to refer to a branch or division of the species possessing genetic traits which distinguish it from other branches or divisions of the same level. Adding to this definition, it will here also be defined as including only those persons who are capable of reproduction with each other without the loss or significant diminishment or alteration of the racially-distinctive genetic traits of either parent stock. The genetically transmitted traits which distinguish a race from other divisions at the same level (i.e., other races) should not be diminished or lost by reproduction within the race. If racially-distinctive traits are lost or diminished by within-group reproduction then the population group is at a level of division too broad and inclusive to be accurately defined as a race. If it is too narrow to be defined as a species, as it does not include all those populations capable of interbreeding, then it is at a level between race and species, which will here be referred to as a subspecies.
The great diversity existing in the human species today is the product of over 100,000 years of divergent evolution. Many of the specific details of that evolution are still not perfectly known or understood, but the fossil record indicates that the genus Homo developed in Africa, and by 1.8 million years ago (the age of fossil remains found on the island of Java in Indonesia) had spread across much of Eurasia where it developed into a variety of regional archaic populations. The genetic evidence from mitochondrial DNA indicates that the modern human species also originated in sub-Saharan Africa, where it began diverging into different populations by 180,000 years ago. By 100,000 years ago some of these populations had migrated out of sub-Saharan Africa and dispersed across Eurasia and North Africa, replacing the regional archaic populations. (The manner of that replacement, and whether or not -- and to what extent -- the modern humans may have interbred with the archaic populations, are subjects of debate.) By 40,000 years ago the divergent evolutionary branching or dividing of the human species had produced five main lines or subspecies which are still extant -- the Congoid and Capoid of sub-Saharan Africa, the Australoid of India, Southeast Asia, Indonesia, New Guinea and Australia, the Mongoloid of Northeast Asia (expanding after 20,000 B.C. into the Americas and replacing the Australoids in Southeast Asia and Indonesia after 4,000 B.C.) and the Caucasoid of Europe, North Africa and West Asia (partly replacing the Australoids in India after 8,000 B.C., the Mongoloids in the Americas after A.D. 1492, and the Australoids in Australia after A.D. 1788). These subspecies branched or divided in turn into separate races, and these races branched in their turn into subraces, as part of the continuing process of divergent evolution.
The different races are often popularly defined and named (often very inaccurately) by skin color, but as this system is based on only one genetic difference, when thousands are involved, it tends to distort the reality of race and racial differences. In the system of racial classification outlined below the names assigned to the various subspecies and races are, with a few exceptions, based on geographical regions that are, or presumably were, at or near the center of their area of evolutionary development and origin.
The diverse races of the human species outlined above all have their own geographical territory that has historically been exclusively their own, which may be referred to as their racial homeland, and is closely identified with the race that inhabits it. Between most of these exclusive homelands are clinal zones -- areas of contact between different racial territories. These racial borderlands are frequently areas of interracial contact and intermixture where adjacent races merge into one another, creating racially mixed or hybridized populations of intermediate type called racial clines. The Dravidic race of India and Sri Lanka, created by the intermixture of the local Caucasoid (Indic or Nordindid) and Australoid (Veddoid) populations, and the Aethiopid race of Ethiopia and Somalia, created by the intermixture of the local Caucasoid (Mediterranid) and Congoid races, are two very ancient racial clines -- perhaps 10,000 years old -- which have stabilized into distinct races of intermediate type. Racial clines of more recent formation, where the racial blends are not yet stabilized, include the populations of many Latin American and Caribbean countries, which were created over the last 500 years by the intermixture of various Caucasoid (mostly Mediterranid), Congoid and Amerindian elements. The population of Mexico, for example, is about 5% Caucasoid, 30% Amerindian and 65% Mestizo, the Spanish term for persons of mixed Amerindian-Caucasoid ancestry. (The same term is used in the Philippines for persons of mixed Filipino-Caucasoid ancestry.) The multiracialization of the populations of North America and, more recently, Europe, has begun to transform them into racial clines. As discussed in other essays on this site, this process of racial transformation will eventually cause the effective extinction or nonexistence of the European racial types in the affected areas unless adequate preservationist measures are taken to prevent it.