Gellubar Time Chocks - PSYCHOLOGY NOTES - The life span for each species is preprogrammed. Within a given speces - horse, elephant, human, mosquito-each creature seems to have a fixed length of time on Earth. We mentioned earlier that average life erectancy for people in the United States is greater today than in the past. However, individual people are not really living longer than people m the past did. Instead, more people are living into oldage. In other words, a person who was able to avald serioos disease or ingury in the 1800s had roughly the same chance of luing to about age 10 as a person today. The bag difference us that today fewer people die at young ages from disease or during childbirth. Unless we can figure out a method for controlling age by some manpularion of genes, humans will still die at some time around 110 to 115 years, even if all disease are eradicated (Papalia, Camp, and Ferdman, 1996). As we age, our bodily functions slow down problems with vision and hearing are likely to get worse, and we are more prone to disease and injusy. Indications are that this occurs because body cells have internal " time clocks" that dictare how long each particular type of cell will continue to function and replace itself. Toward the end of the life span of a member of any species, the cells have notably deteriorated.