Eye color is far more complex than is generally appreciated, ranging from blue, gray, green, green/blue, brown, and others, varying with different populations. As with skin pigmentation, eye and hair color results from the degree of melanin pigment deposited in the tissue. Humans have several eye color genes. Two best understood are named BEY2 (brown eye) located on chromosome 15 and GEY (green/blue eye) located on chromosome 19. Interestingly, the human “secretor” blood type gene is linked to the GEY gene, since they are both found on chromosome 19. This may explain why the percentage of secretors in the population rises as one heads further north, since the percentage of green and blue eyes increases as well.

There is one peculiarity of eye structure which has been used in making racial distinctions called the epicanthic eye-fold, a fold of flesh that covers the upper eyelid, and sometimes even the upper eyelashes, when the eyes are wide open. It gives the eyes a narrower appearance. It may be an evolutionary defense against both the extreme cold as well as the extreme light that occurs in the Eurasian arctic and north. It has also been suggested that the fold provides some protection against dust in areas of desert such as that found in the deserts of northern China and Mongolia as well as parts of Africa.

Although almost universal amongst Central and Northern Asians, there is a wide distribution of the epicanthic fold across the world. It is also found in significant numbers amongst Amerindians, the Khoisan of Southern Africa and some people of Sami (Lapp) origin. The presence of epicanthic folds is common in many, though not all, groups of East Asian and Southeast Asian descent. Due to classic genetics children of a parent with a pronounced epicanthic fold and one without an epicanthic fold will have varying degrees of epicanthic folds as a result. On the other hand, high orbits, with no folds, are characteristic of certain Balkan populations and of most Near Eastern peoples.

Hair texture is measured by the degree of fineness or coarseness, which varies according to the diameter of each individual hair. There are four major types of hair texture, which are fine, medium, coarse and wiry (sometimes referred to as wooly). Head hair grows at the rate of approximately 1.25 centimeters, or about 0.5 inches, per month, and it has been speculated that the significance of long head hair may be adornment leading to what evolutionary biologists call “Fisherian Runaway Sexual Selection”, in which an prospective mate’s health is gauged by lustrous hair, leading to a greater rate of selection for those individuals with the gene –the same mechanism that probably led to those beautiful peacock feathers.

Scalp hair varies tremendously between races; the scalp hair of most Asians has the greatest thickness and the roundest cross-section, which produces a thick, straight hair. In Europeans the hair is more oval and finer; in Negroes it is flattened, resulting in small wiry, or “kinky” curls. There are at least three kinds of kinky hair. There is short kinky hair that covers the whole scalp evenly, as with most African peoples. There is short kinky hair that grows in tufts with seemingly bare spaces between, as in some East African groups. Then there is the longer kinky hair of the peoples of the Southwest Pacific islands. The hair of the Australian Aborigines is curly or wavy, except for one small group in Queensland who have what is called "frizzy" hair, or hair that is slightly kinky. It has been speculated that wiry hair texture has an advantage in being difficult to penetrate by stinging insects and tends to wick sweat effectively, keeping it away from the face, two distinct benefits in hot, humid environments. Only persons of African descent usually have this type of hair, although some Europeans can have extremely curly or frizzy hair.

Blonde hair is produced by an absence of melanin and may be attempt to optimize UV penetration of the scalp (maximizing vitamin D levels in the northern climes)

Having red hair is associated with the recessive version of the MC1R gene on chromosome 16, which also codes for fair skin and freckles. Four out of five redheads have this gene variant, which is found at its greatest frequency in Scotland and Ireland. Some authorities suggest that red-haired people may be descendents of a blending of Neanderthal and Cro-Magnon peoples while others suggest that the gene is more recent, well after the human migration from Africa, so that the geographical distribution of red hair would be due to post-glacial expansions from Europe.

The tendency of the two eyebrows to blend over the nose, called “concurrency” is found in its highest frequency in the Middle East, but is also common among Southern Europeans.