The Odds of Being Born | How lucky you actually are just to be here

November 18, 2019 •

Do you ever stop to think about the probability or your own existence? That is, the chances or odds of being born at all.  When life seems difficult, you can consider yourself to be very lucky just to be alive in the first place.  Let’s delve into this question and find the answer that might surpise you, and why parents might refer to their offspring as a little miracle.

A number of people, including Dr Ali Binazir, have attempted to answer the question by applying probability to a certain number of  logical circumstances and assumptions.  We’ll follow a similar method and throw in some additional and updated ones. 

His estimate, conducted in 2011, starts by calculating the probability of the two people who became your parents actually meeting in the first place.  At the time that he attempted to answer that question, he went on the assumption that those two people may have met one new male or female (respectively) every day in the space of 25 years, starting from the age of 15.

That was ten thousand people, or potential mates (actually it’s 9,131 people to be more exact and including leap years).  However, that assumption did also not account for the fact that some of those people would have been homosexual.  The percentage of gay people is never going to be quantifed exactly, but going by  various studies and surveys we can reduce the figure of 4%.  This then becomes 9,131 x .96, that can be tweaked to 8,766.

Binazir also looked at what the population of the earth was 20 years before his estimate (i.e. in 1991) which assumed that this applied to only 20 year olds.  Let’s focus on the chances of being born today, instead.  Restricting the pool of possible people that you could meet to 10% of the population of the world (7.7 billion in 2019) gives us 770 million, with approximately half being male and the other half female. The updated figure of two people meeting to become parents is therefore 9,131 divided by 770 million.  That’s approximately one in 84,328.

The next step is to consider the odds of the two would-be eventual parents actually having a conversation to get something going in the right direction.  Using the same assumptions of one in ten probability, followed by a further one in ten chance that it could turn into a second meeting (date) and then a one in ten again that it might result in a relationship and then the cutting the odds further by assuming that there is a 50% chance of it resulting in a child being born. This cuts things down to the chances of an eventual birth happening at one in 2,000 (0.1 x 0.1 x 0.1 x 0.5).

From this we can calculate that the chance of birth is actually 1 in 168,656,000 today.

It doesn’t stop there, though.

Further factoring in the same assumptions of the specific egg and exact sperm meeting up at the end of the story is near-on one in four hundred quadrillion. That’s 400,000,000,000,000,000.  Its kind of hard to imagine, isn’t it?

After that, everything is probably going to seem a little incomprehensible, given that when you also consider that the odds of your ancestors (going back to the beginning of time) having also lived to an reproductive age and arriving here after around four billion years is one in ten to the power of 45,000.   That’s too big to represent here without breaking the Internet.

The next consideration is that for every one of those ancestors, the exact sperm and egg also had to meet each other.  So, we need to take the quadrillion for each generation and multiply that by a quadrillion for every generation of which the assumption is 150,000. It yields 1 in 10 to the power of 2,640,000.

So now we can arrive at a number using the calculation as follows:

One in…

10 to the power of 2.64 million x 10 to the power of 45,000 x 2,000 x 84,328

and we’ve not been able to find a calculator that can handle this kind of number, so going with the answer as calculated by Dr Binazir:

The odds of being born are equal to 1 in 102,685,000. The chances are so low that it is effectively zero. 

Therefore, it’s a good thing that we can say that we are here at all.  Are you feeling lucky now?