We no longer need to rely on morphology, to distinguish between different species. DNA analyses can be used to determine the genetic difference between populations, a better way to classify species. While this has not yet been done, a less subjective classification system might say that a genetic distance of less than “x” is a sub-species (race, variety, or breed), of less than “y” but more than “x” is a species, of less than “z” but more than “y” is a genus, and so on.
Applying a bit of egalitarianism, let us begin with the proposition that the same standard of classification should be applied to the classification of all living things. That is, a population of birds, for example, should not be divided into a great many species because of small genetic differences, while populations within Homo, the genus of humans, are classified as a single species, even though the genetic differences between them are greater than the genetic differences between the species of birds.
Applying that bit of inter-species egalitarianism to humans and gorillas, and using genetic distance as the standard to classify populations, since the genetic distance between the two species of gorilla, Gorilla gorilla and G. beringei, 0.04%, is nearly six times less than the genetic distance between (sub-Saharan) Africans (Bantu) and Eurasians (English), 0.23%, either Africans and Eurasians should be classified as two different species or gorillas should be classified as a single species. The genetic distance between the common chimp and the bonobo is 0.103% (Curnoe, 2003, Table2), less than half the English-Bantu genetic distance of 0.23%, and therefore either (at least some) sub-Saharan blacks and Eurasians should be classified as different species or the common chimp and the bonobo (and the two species of orangutan) should be classified as the same species. Although wolves (Canis lupus) and dogs (Canis lupus familiaris) are a different species (lupus) than coyotes (Canis latrans), “… there is less mtDNA difference between dogs, wolves, and coyotes than there is between the various ethnic groups of human beings…” (Coppinger, 1995). It seems that taxonomists have been bending their objectivity a bit.