Humanity Is Getting Dumber
Scientists say that we have much smaller brains [2] than our ancestors had 20,000 years ago [3] … and we might have gotten stupider since agriculture became widespread [4].
Indeed, Huffington Post reports that we’ve probably gotten dumber than even our Victorian ancestors [5]:
A provocative new study suggests human intelligence is on the decline. In fact, it indicates that Westerners have lost 14 I.Q. points [6] on average since the Victorian Era.
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As for Dr. te Nijenhuis and colleagues, they analyzed the results of 14 intelligence studies conducted between 1884 to 2004, including one by Sir Francis Galton, an English anthropologist and a cousin of Charles Darwin. Each study gauged participants’ so-called visual reaction times — how long it took them to press a button in response [7] to seeing a stimulus. Reaction time reflects a person’s mental processing speed, and so is considered an indication of general intelligence.
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In the late 19th Century, visual reaction times averaged around 194 milliseconds, the analysis showed. In 2004 that time had grown to 275 milliseconds. Even though the machine gauging reaction time in the late 19th Century was less sophisticated than that used in recent years, Dr. te Nijenhuis told The Huffington Post that the old data is directly comparable to modern data.
Other research has suggested an apparent rise in I.Q. scores since the 1940s, a phenomenon known as the Flynn Effect [8]. But Dr. te Nijenhuis suggested the Flynn Effect reflects the influence of environmental factors — such as better education, hygiene and nutrition — and may mask the true decline in genetically inherited intelligence in the Western world.
This new research was published in the April 13 issue of Intelligence.
There are several theories for why we are getting dumber, including the following (the first 2 come from the HuffPost article [5]):
(1) Dr. Jan te Nijenhuis points to the fact that women of high intelligence tend to have fewer children [9] than do women of lower intelligence. This negative association between I.Q. and fertility [10] has been demonstrated time and again in research over the last century.
(2) “The reduction in human intelligence … would have begun at the time that genetic selection became more relaxed,” Dr. Gerald Crabtree, professor of pathology and developmental biology at Stanford University, told The Huffington Post in an email. “I projected this occurred as our ancestors began to live in more supportive high density societies [11] (cities) and had access to a steady supply of food. Both of these might have resulted from the invention of agriculture, which occurred about 5,000 to 12,000 years ago.”
(3) Humans evolved to eat a lot of Omega 3s [12]:
Wild game animals have much higher levels of essential Omega 3 fatty acids than domesticated animals. Indeed, leading nutritionists say that humans evolved to consume a lot of Omega 3 fatty acids in the wild game and fish which they ate [13] (more [14]), and that a low Omega 3 diet is a very new trend within the last 100 years or so.
In other words, while omega 3s have just now been discovered by modern science, we evolved to get a lot of omega 3s … and if we just eat a modern, fast food diet without getting enough omega 3s, it can cause all sorts of health problems.
So something just discovered by science can be a central fuel which our bodies evolved to use.
Omega 3s – in turn – boosts intelligence [15] and help prevent cognitive decline [16].
(4) Exercise [17] boosts intelligence [18] … and our ancestors got a lot more exercise than we do!
In addition, high levels of cortisol – the chemical released by the body when one is under continuous, unrelenting stress – and poverty can physically impair the brain and people’s ability to learn [19].
On the other hand, relaxing activities like meditation [20] and prayer [21] have been shown to increase brain mass and connectivity in certain areas of the brain.
Hunter-gatherers had more leisure time [22] – and a more playful attitude [23] – than we do today.
(5) Toxic chemicals in the environment can reduce intelligence. Examples include flame retardant [24], lead [25] (found in many lipsticks [26]), certain pesticides [27] (and see this [28] and this [28]), and fluoride [29].