There were amazing advances in science and technology in the twentieth century.
These advances were not always positive.
The great excitement over the telephone, the automo bile, electricity, and the airplane was quickly overshadowed by the kil ing machines used in the Great War.
Mass communication has been used for mass propaganda.
The United States released atomic bombs over Nagasaki and Hiroshima.
Since World War II, scientists have made tremendous progress in medicine and communication technologies.
The medical revolution began in the late 1800s with the development of the germ theory of disease and continued after World War II.
Scientists discovered vaccines for many diseases.
Death rates and life expectancies were lowered by the medical revolution.
Infant and juvenile mortality remained higher in poor countries than in rich ones, despite the fact that children became more likely to survive their early years.
Medical science has continued to improve.
The eradication of smal pox was announced in 1979.
By this time, transplants of organs had become routine.
In 2003 scientists working on the Human Genome Project announced that they had successfully identified, mapped, andsequenced the entire genome of man beings.
The completion of the project makes it one of the most important scientific developments of all time.
There is a wide gap in health care availability between the rich and poor.
Thousands of people die every day in the developing world from diseases and illnesses that are easy to treat and cure.
Deaths from HIV/AIDS are reaching epic proportions, while Malaria and Tuberculosis continue to be major health problems for young and old alike.
The medical revolution has led to an increase in popu lation growth.
Between 1950 and 1975, the combined populations of Asia, Africa, and Latin America grew at a similar rate, increasing from 1.7bilion to 3bilion.
Family plan ning and birth control were pushed by some governments to slow population growth.
These measures were not always successful.
Culture dictated that a "real man" keep his wife pregnant.
There were reasons for preferring large families.
Farmers needed the help of children at planting and harvest times, and sons and daughters were a sort of social security system for their elders.
In the 1970s and 1980s, population growth in industrialized countries began to decline.
The birthrates in Europe were below the 2.1 level needed to maintain a stable population by the 1990s.
The world's poor women began to have fewer children.
Bar bados, Costa Rica, South Korea, Taiwan, and Tunisia are some of the worst countries in the world.
The birthrate decline in China between 1970 and 1975 was the fastest in recorded history.
Latin America and East Asia experienced large de clines in fertility.
There were many reasons for the decline in fertility among women in the developing world.
The survival of the number of children the couples wanted was dependent on the number of babies dying of disease or malnutrition.
Women had fewer children because of better living conditions and more education.
The introduction of the birth control pill in the early 1960s marked a revolution in birth control techniques, as well as in women taking control of their own fertility.
Family planning was now possible.
Many Roman Catholic countries and most Muslim countries have male chauvinism, religious teachings, and conservative government leaders combined to control the availability and distribution of birth control methods and abortion.
North America, Protestant Europe, the Soviet Union, and East Asia have the lowest birthrates and population growth because of their acceptance of birth control and abortion.
Epidemic diseases pose one of humanity's gravest fears in the early years of the new millennium.
There have been several outbreak of diseases in Africa, including the deadly Marburg virus, as well as an ongoing outbreak of bird flu in Asia.
HIV/AIDS has caused more disruption of human society than any other disease.
According to the Population Division of the United Nations, 36 million people were diagnosed with HIV in 2007.
AIDS was the fourth leading cause of death.
About 90 percent of people who die from AIDS and 86 percent of people who are HIV positive live in Africa.
Widespread disease and poverty are two factors that contribute to the spread of HIV/AIDS in Africa.
Political instability in Uganda and other countries in the corridor running from Uganda to South Africa contributes to the spread of AIDS in Africa.
The scene of brutal civil and liberation wars resulted in massive numbers of refugees, a breakdown in basic health care services, and the destruction of family and cultural networks.
The populations of countries along this corridor have been decimated by HIV/AIDS.
There are more HIV/AIDS cases in South Africa than anywhere else.
According to medical health experts, Rus sia, India, China, Japan, and other countries in Asia might soon overtake South Africa in reported HIV/AIDS cases.