Happy birthday! Do birthdays really make people happy? Of course they do. Birthdays celebrate the day we were born. Besides, that extra candle on the cake suggests another year of growth and maturity (成熟)— or so we hope. We all like to imagine that we're getting wiser and not just older. Most of us enjoy seeing the miracle (奇迹) of growth in others, as well. For instance, seeing our children develop and learn new things makes us feel proud. For Americans, like people in most cultures, growing up is a wonderful process (过程). But growing old? That's a different story. Growing old is not exactly pleasant for people in youth-oriented (以年青人为中心) American culture. Most Americans like to look young, act young and feel young. As the old saying goes, 'You're as young as you feel.' Older people joke about how many years young they are, rather than how many years old. People in some countries value the aged as a source of experience and wisdom. But Americans seem to favor those that are young, or at least 'young at heart'. Many older Americans find the 'golden years' to be anything but golden. Economically, 'senior citizens' often struggle just to get by. Retirement (退休) at age 65 brings a sharp decrease in personal income. Social security (安全) benefits usually cannot make up the difference. Older people may suffer from poor nutrition (营养), medical care and housing. Some even experience age discrimination. In 1987, American sociologist Pat Moore dressed up like an older person and wandered city streets. She was often treated rudely — even cheated and robbed. However, dressed as a young person, she received much more respect. Unfortunately, the elderly population in America is increasing fast. Why? People are living longer. Fewer babies are being horn. And middle-aged 'baby boomers' are rapidly entering the groups of the elderly. America may soon be a place where wrinkles (皱纹) are 'in'. Marketing experts are already noticing this growing group of consumers. Growing up is a wonderful thing because______.