The Flynn Effect describes how IQs rose for the first part of the 20th century.

With all advances in technology, our knowledge about diet and health, and the easy access we have to education, you’d think IQs would continue to rise. And they were. Up until the 21st century, at least, and this is exactly what the Flynn Effect describes. From the early part of the 20th century, IQs were increasing at a rate of 10 points per generation. Which is surprising as the food was pretty basic and health education in its infancy.

However, according to some studies, the early boost in IQ in the 20th century is now falling. All this despite great technological strides, huge leaps in medicine, and access to better nutrition. Experts now suggest that in the last twenty or thirty years, humans have started getting dumber and dumber.

In order to find out why we are dumbing down, let’s explore the Flynn Effect. Why did we get smarter in the first place?

The Flynn Effect and how we got smarter

The Flynn Effect is named after intelligence researcher James Flynn. He observed rapid rises in IQs for every decade in the 20th century. However, it’s a little more interesting than just higher IQ scores. If you delve deeper, it is our fluid intelligence that has risen, more so than our crystallized intelligence.

  • Fluid Intelligence: our ability to solve problems, use logic and understand patterns.
  • Crystallized Intelligence: our ability to use learned information, such as vocabulary and maths skills.

So what was the reason for the Flynn Effect?

Researchers put the increased IQ down to, not one, but several factors:

You could say that the Flynn Effect is down to our progress as a species. So why, as we are still evolving, is our IQ now dropping? The data shows that from the 1970’s onwards, our intelligence has started falling.

In one study, data was used from compulsory IQ tests given to young Norwegian military servicemen between 1970 and 2009. Over 730,000 results were collected. The results suggested that each generation dropped an average of 7 IQ points.

The study authors say:

“…our results remain consistent with a number of proposed hypotheses of IQ decline: changes in educational exposure or quality, changing media exposure, worsening nutrition or health…”

So why is humanity getting dumber?

Here are five possible reasons:


In the 20th century, pupils learnt by studying and then completing coursework which would be graded at the end of a term. This would typically be followed by an exam to complete the course. This system allowed students to use logic and abstract thinking when carrying out their coursework.

In the last few decades, the education system has completely changed. There is no longer the option of coursework, where a student can carry out their own research and use their fluid thinking. There is just one exam at the end of a term. All you need for this exam is the ability to recall information. In other words, crystallized intelligence.

By teaching in this way, we are not getting our children to use their full potential.

  1. WORK

Is work an important source of our cognitive development? In the US, one study revealed an interesting correlation between intelligence and the rise of certain types of work and the fall of others:

From 1990 to 2012:

  • ‘Working Class’ jobs fell drastically from 31.4% to 20.5%
  • ‘Creative Class’ jobs rose slightly from 29.3 to 32.0
  • ‘Service Class’ jobs rose drastically from 39.3 to 48.5

Service class jobs include personal care assistants, nursing assistants, retails sales, food preparation workers (McDonald’s), all classed as low-skilled. In order to carry out these low skill jobs, you do not need to think on your feet, or to be able to solve problems quickly. Most of your work is mundane and routine.

In other words, you do not need fluid intelligence, crystallized intelligence will do just fine. With more and more people going into these kinds of service jobs, where employment is being deliberately ‘dumbed down’, could this be a reason for falling IQs?

  1. FOOD

Despite much education about healthy food and what is bad for us, in 2016, more than 1.9 billion adults were classed as obese. Being overweight isn’t just bad for your body, it is also bad for your brain. Obesity causes high blood pressure and inflammation, which irritates the brain’s communication signals.

This means it is harder for messages to get through. Being obese also disrupts the brain’s memory functions and the areas associated with decision-making.

Back in the early 20th century, there were many social aspects that affected the way we ate. Women tended to be at home, making meals from scratch and families would sit around the table together. These days, both parents are out working, ready meals are available, if not a takeaway, and kids eat up in their bedrooms with no social interaction.


Another reason for declining IQ scores, in the Netherlands and the US at least, could be a factor of immigration. Data reviewed from studies of young Danes who were children of immigrants to the country showed a poor performance on IQ tests. This was compared to the local children.

Of course, there could be a number of reasons; poverty, malnutrition, poor health, all of these depress IQ. The rise of immigrants to developed countries such as Denmark, the Netherlands and Norway are on the increase. This could result in further decreases in IQs in those regions.


My final thought is that the kind of celebrity we are aspiring after also has an effect on our brains. Decades ago, celebrities were untouchable, they were famous for doing something incredible, achieving great things.

Nowadays, you can get your private parts out, release a sex tape, or have sex on TV and become an overnight success. In the UK, we have a ‘celebrity’ who cannot tell the time. He is renowned for being stupid. These are our role models for the younger generation. And we wonder why IQs are falling?

Do you think we are getting dumber or do you disagree with the Flynn Effect altogether?



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