Ponytail

To make a ponytail, some, most or all of the hair on the head is pulled away from the face, gathered and secured at the back of the head with a hair tie, clip, or other similar device and allowed to hang freely from that point. It gets its name from its resemblance to the undocked tail of a horse or pony. Ponytails are most commonly gathered at the middle of the back of the head, or the base of the neck. Depending on fashions, they may also be worn at the side of the head (which is sometimes considered formal) which is worn over one ear, or on the very top of the head (allowing the hair to fall down the back or one side of the head).

If the hair is divided so that it hangs in two sections they are called "ponytails", bunches, or pigtails if left loose, and pigtails or braids if plaited. Unbraided ponytails worn above each ear are sometimes called dog-ears.

It is common for those who wear tight ponytails to experience traction alopecia, a form of hair loss. Sometimes it can cause a headache.

Long hair

Long hair is a hairstyle where the hair is allowed to grow to considerable length. Exactly what constitutes long hair can change from culture to culture, or even within cultures. For example, a woman with chin-length hair in some cultures may be said to have short hair, while a man with the same length of hair in some of the same cultures would be said to have long hair.

Males having short, cut hair is in many cultures viewed as being under society's control, such as while in the military or prison or as punishment for a crime, while males having long hair signifies being outside of the mainstream. Long lustrous female hair is rated attractive by both men and women across cultures. The prevalence of trichophilia (hair partialism or fetishism) is 7% in the population, and very long hair is a common subject of devotion in this group.

Biological significance

Humans, horses, and orangutangs are among the few species that may grow their head hair very long. Humans are believed to have lost their fur 2.5–3 million years ago when transitioning from a forest habitat to the open savanna, as an effect of natural selection, since this development made it possible to run fast and hunt animals close to the equator without getting overheated. An exception was however head hair, which was kept to provide thermal insulation of the scalp from the sun, to protect against ultra-violet radiation exposure, and also to provide cooling (when sweat evaporates from soaked hair). The ability to grow straight hair, has been observed among Homo sapiens sub-groups in less sunny regions further away from the equator. Relative to kinky Afro-textured hair, straight hair allows more UV light to pass to the scalp (which is essential for the production of vitamin D, that is important for bone development).