Aging is an inescapable fact of human life. In most areas of our lives, aging leads to an unremarkable, gradual decline in physical ability. For example, no one questions why a 40-year-old runner can no longer compete in the Olympics. As the body ages, metabolism slows, joints wear out, and energy is diminished. Aging also has a uniform natural effect on the learning of new skills. As a result, we are not surprised to find that someone who tries to learn soccer at age 30 makes less progress
... someone who begins learning at 12. We approach these gradual age-related physical declines and losses in learning ability with equanimity, since few of these skills are crucial for everyday functioning. No one would suggest that these declines represent the sudden expiration of a some innate ability linked to a specific biological time fuse. However, when we look at the decline in language learning abilities that comes with age, we assume a somewhat different position. We are distressed to find that a 35-yearold Romanian immigrant to the United States is unable to lose her Romanian accent, saying that this may limit her ability to adjust to the new society. We may wonder whether the observed fossilization represents the final expiration of some special gift for language learning. Or we may worry that a 28-year-old graduate student from Japan has trouble learning to use English articles. If these error patterns continue year after year, we say that the language spoken by these immigrants has "fossilized" (Selinker, 1972).