The population of the earth continues to grow at a fast pace. It took 5,800 years from man's creation by God (Adam was made around 3984 B.C.) for the world's total number of people to reach one billion. It took one hundred and ten years after reaching this landmark for the population to reach two billion in 1930 A.D. It took only another thirty years for the number of humans to reach three billion. In 1974, only fourteen years later, the globe's number of human beings stood at four billion.
It took only thirteen years after 1974 for the earth to reach the milestone of five billion humans. The number of humans then climbed to six billion in 1999 and, as of July 2013, stands at an estimated 7.1 billion.
One of man's great challenges in the 21st century is how to balance the increases in life spans brought by technological advances versus the increasing demand of resources required to support a larger living population.
Legal systems in the world
The legal systems of nearly all countries on earth generally fall into one of five main categories.
Civil Law, which is any legal system based on the Roman system
Common Law, which is a set of rules based on judicial decisions and custom. Common law is a part of the legal system in the United States. One example of common law can be found in regard to who is considered legally married. In most (if not all) U.S. states a couple is considered legally married if, in spite of not having a valid marriage certificate, they have lived together for a certain set number of years.
Customary law, which is based on an established pattern of behavior that is objectively verifiable within a particular social setting.
Mixed law, which is a system that is a mix of other legal systems (e.g. Civil and common law)
Religious law, which is a system based on religious beliefs. For example, Iran is a country which is governed by a religious legal system based on Sharia (Islamic) law.