Intro-Life Expectancy-Sensory-Abilities

INTRO  True/False  Older People Become more susceptible to short-term illnesses.  During old age many of the brains neurons die  If they live to be 90 or older, most elderly people eventually become senile  Recognition memory-that ability to identify things preciously experienced-declines with age  Life satisfaction peaks in the fifties and then gradually declines after age 65

Life Expectancy  Worldwide, life expectancy at birth increased from 49 years in 1950 to 67 in 2004-and to 80 and beyond in some developed countries  Combined with decreasing birthrates making the elderly population bigger  By 205 about 35% of Europe’s population will be over 60  Life expectancy differs for males and females; males are more prone to dying. Although 126 male embryos begin life for every 100 female who do so, the sex ratio is down to 105 males for every 100 females at birth  During the first year, male infants; death rates exceed females’ by ¼  Women outlive men by 4 years worldwide and by 5-6 years in Canada, United States, and Australia.  By age 100 females out live males 5 to 1  Even if no one died before age 50, cancer, heart disease, and illnesses were eliminated, average life expectancy would increase only to 85 or a few more years  Once We’ve fulfilled our gene-reproducing task, there are no natural selection pressures against genes that cause degeneration in the later life

Sensory abilities PPhysical decline starts in early adulthood, but we are not aware until later life. VVisual sharpness diminishes, and adaptation to changes in light levels slows. MMuscle strength, reaction time, and stamina also diminish noticeably, as do hearing, distance perception, and the sense of smell IIn late life the stairs get steeper, the print gets smaller, and people seem to mumble more. TThe eye’s pupil shrinks and its lens becomes less transparent, reducing the amount of light reaching the retina. A 65-year-old retina receives only about one-third as much light as its 20-year-old counterpart TTo see as much as the 20-year-old, the 65-year-old needs to receive 3 times as much light