# Birthday age question... **URL:** \ **Category:** Factual Questions\ **Created:** [April 26, 2012, 3:25pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027 "2012-04-26T15:25:05Z")\ **Posts on this page:** 9\ **Page:** 3
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [April 27, 2012, 3:35pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/41 "2012-04-27T15:35:44Z")
> [@TriPolar](#): > > That’s kind of like asking kids what grade they are in at school. But I don’t know an English word that conveys the same thing. “Coeval” or “contemporary” would be the closest thing I can think of, but it doesn’t necessarily mean someone born in **exactly** the same year. “Agemate” is a less common synonym, but again doesn’t imply exact identity of birth year. ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [April 27, 2012, 4:42pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/42 "2012-04-27T16:42:58Z")
> [@Colophon](#): > > **Chessic Sense** , I don’t follow your logic. Even if you count down to the hours and minutes… Yes, but I said if you don’t count down to the hours and minutes. If you’re born in the afternoon, you’re treated like you were born 13-sumn hours earlier. Years later, the current time is treated like it’s just before midnight. > [@Colophon](#): > > But being alive on _X_ days isn’t the same as being _X_ days old. Just the same as being alive in _Y_ years isn’t the same as being _Y_ years old. Right. Technically, it’s inaccurate to the hours-scale, but who cares? If you’re alive at any time of that day, you get credit for the full day. > [@Chronos](#): > > For that matter, there have been a handful of people who’ve been alive in three centuries. Would you say that they were three centuries old? You could, if being precise wasn’t important. If a wall was built in the first century and it’s now the 21st century, hasn’t it been around for 2,000 years? Give or take, right? > [@Greg\_Charles](#): > > In Viet Nam, they told me they counted a newborn as one year old because of the time in the womb (rounded up I guess), and not because of elapsed years vs. current years. Interestingly, they generally count another year on Tet rather than birthdays, because often people, especially in the countryside, don’t remember when their birthdays are. I joke with them that since I was born six days before Tet, I was two years old before I was a week old. There are many, many countries in the world where birthdays are irrelevant. I can’t tell you how many Iraqis were born on “January 1st”. If an Iraqi tells you his birthday is July 1st, he means “There were sandstorms around the time I was born.” ---
**Author:** ![RedSwinglineOne](https://avatars.discourse-cdn.com/v4/letter/r/a9adbd/32.png) [@RedSwinglineOne](https://boards.straightdope.com/u/RedSwinglineOne)\ **Post date:** [April 27, 2012, 10:40pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/43 "2012-04-27T22:40:28Z")
> [@bmasters1](#): > > Why is it, according to the rules of birthdays, that in order to get another figure added onto your age, you must reach your DOB in the following calendar year? My guess is that it is because infant mortality rates were once very high, and it was an achievement to reach 1 year. (hence the celebration) So we are basically recording the years we have survived, not the years in which we have existed. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [April 28, 2012, 7:36am UTC](https://boards.straightdope.com/t/birthday-age-question/620027/44 "2012-04-28T07:36:33Z")
> [@RedSwinglineOne](#): > > My guess is that it is because infant mortality rates were once very high, and it was an achievement to reach 1 year. (hence the celebration) So we are basically recording the years we have survived, not the years in which we have existed. This hypothesis is not supported by the available evidence. The system immediately preceding our current “count birthday anniversaries”-method appears to have been dominated by variants of “in his xth year”. The conversion is more likely to have to do with an increasing availability of calendars and the accompanying focus on the actual numbers involved. It wouldn’t surprise me if birthday celebrations in general don’t become rarer and rarer as we look back either. Now there are old systems, like the aforementioned counting of winters and springs, based on survival, but as they’re not the immediate predecessors of our current system and count other things than birthdays, I don’t see this as supporting your hypothesis. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 28, 2012, 7:52am UTC](https://boards.straightdope.com/t/birthday-age-question/620027/45 "2012-04-28T07:52:59Z")
> [@](#): > > You could, if being precise wasn’t important. If a wall was built in the first century and it’s now the 21st century, hasn’t it been around for 2,000 years? Give or take, right? Yes, but it hasn’t been around for 2100 years. The analogous calculation for someone born in the 19th century and still alive in the 21st century would be that they’re 200 years old (which is at least correct if you’re rounding up), not that they’re 300 years old. ---
**Author:** ![UltraVires](https://avatars.discourse-cdn.com/v4/letter/u/ecccb3/32.png) [@UltraVires](https://boards.straightdope.com/u/UltraVires)\ **Post date:** [April 29, 2012, 4:57pm UTC](https://boards.straightdope.com/t/birthday-age-question/620027/46 "2012-04-29T16:57:52Z")
How would this work for other legal purposes? Say a person was born at 11pm on May 3rd, 1991. Does that mean he could walk into a bar at 2 seconds past midnight on May 2 (2 seconds away from May 1) and be legally served a drink? He’s almost two full days shy of being 21. How about 2 seconds after midnight on May 3rd? He is still only 20 years 364 days and 1 hour old. That is less than the 21 year minimum age required by law. Are bartenders and police trained in this area? ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 30, 2012, 1:37am UTC](https://boards.straightdope.com/t/birthday-age-question/620027/47 "2012-04-30T01:37:25Z")
> [@jtgain](#): > > How would this work for other legal purposes? Say a person was born at 11pm on May 3rd, 1991. Does that mean he could walk into a bar at 2 seconds past midnight on May 2 (2 seconds away from May 1) and be legally served a drink? He’s almost two full days shy of being 21. > > How about 2 seconds after midnight on May 3rd? He is still only 20 years 364 days and 1 hour old. That is less than the 21 year minimum age required by law. > > Are bartenders and police trained in this area? Notwithstanding the SSA ruling cited earlier by **Kimmy\_Gibbler** , legally, they’re going to look at the birth date on your driver’s license. You are considered 21 starting on the day of the anniversary of your birth. I read the cite but I have never heard of **Kimmy\_Gibbler** ’s accompanying claim that this is common law, nor was that aspect cited in the post. I have seen signs up at cash registers in the grocery store reminding cashiers with wording like, “Anyone purchasing alcohol must have a birthday on today’s date in the year 1991, or earlier.” I think they must update it every year. If he walks into a bar on May 3rd, 2012, he will be served, regardless of what time it is–12:01 AM, 2:00 PM, or 11:30 PM. And the time of day that you were born is irrelevant. As an example, Virginia law says you must have attained 21 years of age but doesn’t define on what day that occurs. ---
**Author:** ![Kimmy\_Gibbler](https://avatars.discourse-cdn.com/v4/letter/k/bbe5ce/32.png) [@Kimmy\_Gibbler](https://boards.straightdope.com/u/Kimmy_Gibbler)\ **Post date:** [April 30, 2012, 4:43am UTC](https://boards.straightdope.com/t/birthday-age-question/620027/48 "2012-04-30T04:43:20Z")
> [@CookingWithGas](#): > > Notwithstanding the SSA ruling cited earlier by **Kimmy\_Gibbler** , legally, they’re going to look at the birth date on your driver’s license. You are considered 21 starting on the day of the anniversary of your birth. I read the cite but I have never heard of **Kimmy\_Gibbler** ’s accompanying claim that this is common law, nor was that aspect cited in the post. > > I have seen signs up at cash registers in the grocery store reminding cashiers with wording like, “Anyone purchasing alcohol must have a birthday on today’s date in the year 1991, or earlier.” I think they must update it every year. If he walks into a bar on May 3rd, 2012, he will be served, regardless of what time it is–12:01 AM, 2:00 PM, or 11:30 PM. And the time of day that you were born is irrelevant. > > As an example, Virginia law says you must have attained 21 years of age but doesn’t define on what day that occurs. Well, I also cited a federal court of appeals and a number of state supreme courts. A bar doesn’t have to serve anyone they don’t want to (or, at least, twenty-one-year-minus-one-day-olds are not a protected class). Were such a person charged with underage drinking, they could use this case law to beat the rap. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [April 30, 2012, 11:51am UTC](https://boards.straightdope.com/t/birthday-age-question/620027/49 "2012-04-30T11:51:05Z")
> [@Kimmy\_Gibbler](#): > > Well, I also cited a federal court of appeals and a number of state supreme courts. A bar doesn’t have to serve anyone they don’t want to (or, at least, twenty-one-year-minus-one-day-olds are not a protected class). Were such a person charged with underage drinking, they could use this case law to beat the rap. My mistake, I looked only at your first post. From what I have seen they try to keep things brain-dead simple for convenience store clerks and bar bouncers. I don’t know the technicalities of what would happen if such a case went to court. [Previous page](https://boards.straightdope.com/t/birthday-age-question/620027.md?page=2)