The celebration of birthdays is naturally dependent upon having a calendar or being well-acquainted with astronomical configurations. More than that, it depends upon cultural value being given to celebrating a person’s birth every year. There is evidence that the pagans recognised birthdays to enable the casting of horoscopes, but the early Christians did not do so, both because they were pagan and due to their belief that they were satanic ~ likening one’s existence to that of a god.
Nevertheless, by the fourth century the Christians had accepted the popular desire to celebrate birthdays. The Germans are credited with the origin of birthday cakes with one candle for each year of life, plus one for luck! In the UK, it was the Victorian era’s sentimentality which saw the growth of birthday parties, gifts, cakes and cards. The ‘Happy Birthday’ song appears to originate in the USA at this time.
Today, almost everyone in the UK expects birthday greetings from their family and friends. Children’s birthday parties can be quite expensive. Adults may have parties for certain milestone ages ~ namely, 18, 21, 30, 40, 50, 60, 70, 80, 90, 100, 105 and every year after that! From age 100, the government will organise a birthday congratulations message from the Queen on application.