But now, some scientists fear that we are starting to reverse those gains.
A nation of genres
For the last century, we have become smarter – quicker. The average IQ of the population has increased by about three points per decade.
Mensa has also noticed. "Our membership grows by around 10% in the year," says Teresa Wong, who is responsible for hiring the organization. "And about a third of them are under the age of 18."
If we were to test people today using intelligence tests of the 50s, 75% of the population would be classified as gifted (to cope with this, the tests of intelligence are made progressively progressively harder).
This has had significant benefits.
"We know we are less violent for a long time, it seems we live longer and we are healthier, we have more complex lives, more complex skills, we can drive cars, we can do all sorts of things, we are accelerating and becoming smarter, "says dr. Tony Florio, clinical psychologist and lecturer at the University of New South Wales.
The same increase in IQ in the last century occurred in almost every other developed nation. It is known as Flynn effect after James Flynn, the New Zealand researcher who discovered it.
There are several theories about why this has happened: we are more educated, modern educational systems shape our brains in ways that tests of intelligence tend to please and many of us will deal with things with cognition how to play video games during our hours of leisure.
But as a society, we have also become healthier. Eat better Modern medicine means that childhood diseases are less likely to stop brain development. Some even suspect that the gradual elimination of lead in fuels has played a role. For the same reasons that later generations are taller, they are probably even smarter.
But it seems that something strange and disturbing is happening. In several countries – Norway, Denmark, Finland, Great Britain and France – the IQ scores that have increased for so long seem to decrease, with a rate of around 2.4 points per decade in the last decades.
Considering these countries all have reflected our IQ increase, it is plausible that the Australian IQ is heading downwards.
Scientists initially suspected that because people with higher IQ tend to have fewer children, the average intelligence would slowly decrease over time. But a recent document, published in PNAS in June, seems to exclude this fact by demonstrating that IQ is falling even into households .
After 1975, on average, older siblings tended to be smarter than younger siblings – an inversion of the trend up to that time. So they are not geniuses, nor natural selection.
The rise of the smartphone.
Could it be that our smartphones are making us more stupid?
We can look for any fact in an instant. We never need to remember facts or directions or phone numbers of friends. Does this make us more stupid?
The picture is complicated and there is not enough evidence yet to really say it in one way or another. But several interesting studies indicate that smartphones have at least some effect on cognition. The studies have linked the use of smartphones with a reduced ability to exercise a high level of attention and less attention control – even if video games seem to be linked to better multitasking skills.
In an influential study, volunteers were asked to type recent computer trivia facts. Those who were informed of the fact that the computer would have remembered the facts for them behaved much worse in a subsequent memory test. The researchers dubbed the effect Google .
In another study, the volunteers received a series of questions that pushed the limits of their brains. Those who claimed to be heavy smartphone users tended to get worse and be less analytical. Poor academic performance has also been linked to the heavy use of smartphones.
Even more dramatic was a 2013 experiment in which volunteers were given a camera and asked to take pictures of various objects in a museum while looking at the other objects. A day later, they were able to remember better to have seen the objects that had not photographed.
Smarter – or better adapted?
Does this make us more stupid? Or does our brain simply adapt to the needs of the modern world?
Flynn himself claims that his eponymous "effect" does not necessarily show us we are becoming more intelligent – it's just that our brain has become more modern & # 39;
"We had a lot more common sense and we understood things more from our common experience," says dr. Florio.
"There is less emphasis on mechanical learning today, I teach students and their writing is worse because they are more keyboard-dependent, I do not think children can multiply in their heads just as easily."
Liam is a scientific journalist of Fairfax Media