According to Genesis in the Old Testament Adam was created from the earth by God (there is a word play on Hebrew אֲדָמָה (ʾaḏama) meaning "earth"). He and Eve were supposedly the first humans, living happily in the Garden of Eden until they ate the forbidden fruit from the tree of knowledge of good and evil. As a result they were expelled from Eden to the lands to the east, where they gave birth to the second generation, including Cain, Abel and Seth.
As an English Christian name, Adam has been common since the Middle Ages, and it received a boost after the Protestant Reformation. A famous bearer was Scottish economist Adam Smith (1723-1790).
This name died out after the Middle Ages, but was revived in the 19th century. In America and other countries it became fairly popular in the second half of the 20th century. A famous bearer of the surname is former basketball star Michael Jordan (1963-).
In the United States this form was more popular than the full form Elizabeth from 1958 to 1978, and was in fact the top ranked American name between 1962 and 1969.
The name was common among Jews in the Middle Ages, but it was not generally used as a Christian name in the English-speaking world until after the Protestant Reformation. It was moderately popular in the first half of the 20th century, but starting in the 1960s it steadily rose, reaching highs in the 1980s and 90s. The character Rachel Green on the American sitcom Friends (1994-2004) may have only helped delay its downswing.
Notable bearers include American conservationist Rachel Carson (1907-1964), British actress Rachel Weisz (1970-), and Canadian actress Rachel McAdams (1978-).
Its modern use as a feminine name may have been influenced by the British-American author Taylor Caldwell (1900-1985). Since 1990 it has been more popular for girls in the United States. Other England-speaking regions have followed suit, with the exception of England and Wales where it is still slightly more popular for boys. Its popularity peaked in America the mid-1990s for both genders, ranked sixth for girls and 51st for boys. A famous bearer is the American musician Taylor Swift (1989-).