Graph Showing The Most Common Birthdays Suggests That There’s A “Mating Season” Among Humans

Some say that “statistics mean nothing to the individual”. Sure, one could argue that statistics may not necessarily apply to specific people, but they still, nevertheless, explain our reality—the likelihood and possibility of certain circumstances and situations to happen given the number of cases over an average arbitrary measure.

Data Is Beautiful (r/dataisbeautiful), a significantly large subreddit (a subsection) of the forum-like social media Reddit, is dedicated to celebrating the various bits and pieces of information in the form of graphs and charts. One of the more recent posts to find itself here is an interesting graph showing the most and least common birthdays in the United States.

Ever noticed how there are more birthdays happening in the summer than in any other season?

Graph Showing The Most Common Birthdays Suggests That There's A “Mating Season” Among Humans

Image credits: Bo McCready / SSA

The graph is divided up into individual days and months of the year, covering a span of 14 years between 2000 and 2014. Each day is color-coded using varying shades of blue, orange or gray. Blue means that a particular day has more births than usual, while the orange means it has less. Gray indicates that it’s relative to the average.

The numbers provided in each block indicate the margin by which the birth rate exceeds or falls short of the average, which is equal to 1. Anything under a 1 means that it’s not a popular birthday, while anything over that number means it’s common.

A Redditor recently compiled a beautiful graph showcasing the most and least common birthdays

Graph Showing The Most Common Birthdays Suggests That There's A “Mating Season” Among Humans

Image credits: Bo McCready / SSA

According to this data, which is based on information made public by the Social Security Administration of the United States, “birthday season” starts sometime in June and ends in October. For the years 2000–2014, the most common birthdays were in September, namely the 12th and the 19th.

Fun fact, for the longest time, September 9th used to be the most popular birthday, but the 12th and the 19th were always hot on its heels. It is speculated that September is the most popular month for birthdays due to the fact that holiday season is 40 weeks prior to this, and, statistically speaking, more couples have sex during vacation time.

Turns out, summer is birthday season with September being the most popular month in that regard

Graph Showing The Most Common Birthdays Suggests That There's A “Mating Season” Among Humans

Image credits: cobaltfish

This is paired up with a theory proposed by researchers at the University of Texas School of Medicine back in 2001 stating that there is reason to believe that winter is a more suitable time for reproduction due to the changes in daylight length, the variation in quality of the reproductive functions, and whatnot.

The least popular day is, however, Christmas (December 25th), followed by New Year’s (January 1st), Christmas Eve (December 24th), and surprisingly the US’ Day of Independence (July 4th).

The least common days are Christmas, Christmas Eve, New Year’s, and, surprisingly, 4th of July

Graph Showing The Most Common Birthdays Suggests That There's A “Mating Season” Among Humans

Image credits: Bo McCready / SSA

Now, it’s quite sensible to say that you don’t really choose when to give birth—the body and the baby sort of decide the specifics, so it’s interesting to see these particular days, even within “the season”, to be the least common. It is also interesting to see how the 13th of each month is noticeably less popular than the adjacent days.

Another graph, also found on Reddit, covers a different time span, namely the ten years between 1994 and 2003, but shows pretty much the same results: birthing season is mid to end summer and September is still king.

It also points out that the 13th day of each month is often noticeably less common compared to adjacent days

Graph Showing The Most Common Birthdays Suggests That There's A “Mating Season” Among Humans

Image credits: Bo McCready / SSA

It also gives other fun tidbits of information, like the most popular significant dates as birthdays being Valentine’s Day (February 14th), Friday 13th, and April 20th, a significant date in cannabis culture. The most popular day of the week is Tuesday, followed by Thursday, Wednesday, and Friday with the least popular being Sunday.

In much of the world, September stays the most popular month for birthdays, though the birthday season is slightly pushed towards winter season in countries within the tropical zone, and towards spring in the south temperate zone.

So, what are your thoughts on this? Were you born during the time when it’s cool to be born, or are you happy that your birthday is more personal as less people were born on it? Let us know in the comments section below!

Here’s how people reacted to these findings

Graph Showing The Most Common Birthdays Suggests That There's A “Mating Season” Among Humans

Some time ago, Robertas used to spend his days watching how deep the imprint in his chair will become as he wrote for Bored Panda. Wrote about pretty much everything under and beyond the sun. Not anymore, though. He's now probably playing Gwent or hosting Dungeons and Dragons adventures for those with an inclination for chaos.

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Lukas is a photo editor at Bored Panda. 4th year in Vilnius Gediminas Technical University as a graphic designer. Can do whatever he sets his mind to.

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Lukas is a photo editor at Bored Panda. 4th year in Vilnius Gediminas Technical University as a graphic designer. Can do whatever he sets his mind to.

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What do you think ?

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mph seti 4 years ago (edited)

It just means people have a little more sex around the holidays, and when it's cold. Makes sense.

18points

RaroaRaroa 4 years ago

My husband and two of his siblings are all born in November. Seems like a Valentine's day tradition for their parents. :-D Other sybling was born in August but, researching the family tree (birth date versus parents' recorded wedding date) I have my suspicions planning didn't come into it for the eldest. ;-)

7points

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Parmeisan 4 years ago

I was curious about Feb 29 too, so I found this in the linked source: "I used average births per day to adjust for the number of times each day occurs. EDIT: a lot of people have commented that this is confusing. I agree! I should have excluded February 29 or added a note explaining how I handled it."

7points

Parmeisan 4 years ago

In addition to the mentioned fact that fewer people schedule C-sections on holidays & "bad" days, sometimes it can be a conscious plan with other types of births as well. e.g. trying to induce the birth sooner to avoid the child having to share their birthday with Christmas, or trying to wait. Not always successful of course but I can see people trying. Maybe some hospitals will even let you fudge the numbers if you're close enough to midnight? Would definitely explain why Sept 12 is so popular if the 11th is least popular.

3points

Enuya 4 years ago

I don't know how it is in US, but in my country it is quite common that if someone is born close to midnight, then doctor may alter their date of birth. Especially when it comes to Dec 31/Jan 1, because this one day determines whether the child will go to school one year later or sooner. I believe that's also why all 13th days are less popular since 13 is regarded as unlucky number...

4points

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