most people would like to enjoy a long and healthy life.in many countries,there is more change of doing that now then in the past.until recently,many babies died at b irth .for thousands of years .the life expectancy of new generations grew very little.ninety years ago ,a new born baby could expect to live to be about forty-five.

nowadays it can expect to live to seventy .some experts predict that,in the near future ,that figure will be 120.each generation now has the chance to live longer and healthier than before.what are the reasons for these changes ?will they continue ?the dictionary defines research as a careful study to find out facts and informations. many changes in health care have happened because of research.medical researchers ask such questions as:

why do some people live longer than others ?what cause diseases?how can diseases such as cancer be cured?after asking the questions ,they look for the answers .they may look closely at groups of people.for instance ,they may try to find out what makes one group different from another.take the example of heart attacks .researchers have noticed that people who live in western countries suffer more from heart attacks than people in countries of the far east .

in America ,for example ,heart disease has recently killed more people who were around forty or fifty years old than any other disease .in japan ,very few people of this age have heart problems .researchers asked a number of questions ,like:why is this?are people made differently in different parts of the world ?in order to look for the answer,they studied the habits of those groups which had fewer.after lot of research,they found out that such things as smoking ،diet and exercise affect people's hearts.

people who smoke, eat fatty foods and do not exercise are more likely to have heart attacks than others. more westerns than Japanese have these habits.the researchers also found that some Japanese who had become American citizens developed these habits and began to suffer from more heart attacks. researchers have concluded that such personal habits affect human bodies in the same way all over the world.we can all learn from this .if we have habits that endanger our health ,we can change them.