With the rise of eugenics in the latter part of the nineteenth century, such deviations were viewed as dangerous to the health of entire populations.With disability viewed as part of a person's biological make-up and thus their genetic inheritance, scientists turned their attention to notions of weeding such "deviations" out of the gene pool.
Contemporary understandings of disability derive from concepts that arose during the West's scientific Enlightenment; prior to the Enlightenment, physical differences were viewed through a different lens.
During the Middle Ages, madness and other conditions were thought to be caused by demons.
Physiological functional capacity (PFC) is a related term that describes an individual's performance level.
It gauges one's ability to perform the physical tasks of daily life and the ease with which these tasks are performed.
Disability substantially affects a person's life activities and may be present from birth or occur during a person's lifetime.
Disabilities is an umbrella term, covering impairments, activity limitations, and participation restrictions.
In handicap racing, horses carry different weights based on the umpire's estimation of what would make them run equally.
The use of the term to describe a person with a disability – by extension from handicap racing, a person carrying a heavier burden than normal – appeared in the early 20th century.
Foremost among these was the development of clinical medical discourse, which made the human body visible as a thing to be manipulated, studied, and transformed.
These worked in tandem with scientific discourses that sought to classify and categorize and, in so doing, became methods of normalization.