Origin of intelligence, mental illness linked to ancient genetic accident

Scientists have discovered for the first time how humans – and other mammals – have evolved to have intelligence.

Researchers have identified the moment in history when the that enabled us to think and reason evolved.

This point 500 million years ago provided our ability to learn complex skills, analyse situations and have flexibility in the way in which we think.

Professor Seth Grant, of the University of Edinburgh, who led the research, said: "One of the greatest scientific problems is to explain how intelligence and complex behaviours arose during evolution."

The research, which is detailed in two papers in , also shows a direct link between the evolution of behaviour and the origins of .

Scientists believe that the same genes that improved our mental capacity are also responsible for a number of .

"This ground breaking work has implications for how we understand the emergence of and will offer new avenues for the development of new treatments," said John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, one of the study funders.

The study shows that intelligence in humans developed as the result of an increase in the number of brain genes in our evolutionary ancestors.

The researchers suggest that a simple invertebrate animal living in the sea 500 million years ago experienced a 'genetic accident', which resulted in extra copies of these genes being made.

This animal's descendants benefited from these extra genes, leading to behaviourally sophisticated – including humans.

The research team studied the of mice and humans, using comparative tasks that involved identifying objects on touch-screen computers.

Researchers then combined results of these behavioural tests with information from the genetic codes of various species to work out when different behaviours evolved.

They found that higher mental functions in humans and mice were controlled by the same genes.

The study also showed that when these genes were mutated or damaged, they impaired higher mental functions.

"Our work shows that the price of higher intelligence and more complex behaviours is more mental illness," said Professor Grant.

The researchers had previously shown that more than 100 childhood and adult brain diseases are caused by gene mutations.

"We can now apply genetics and behavioural testing to help patients with these diseases", said Dr Tim Bussey from Cambridge University, which was also involved in the study.

Related Stories

Schizophrenia improved by mental and physical exercise

Aug 02, 2007

Dr Anthony Hannan, along with Dr Caitlin McOmish, Emma Burrows and colleagues, characterised a genetically altered mouse and discovered that it had schizophrenia-like behaviours, including learning and memory problems, the ...

Severe mental retardation gene mutation identified

Mar 20, 2007

Researchers have identified a novel gene mutation that causes X-linked mental retardation for which there was no previously known molecular diagnosis, according to an article to be published electronically on Tuesday, March ...

Recommended for you

Know the brain, and its axons, by the clothes they wear

Apr 18, 2014

(Medical Xpress)—It is widely know that the grey matter of the brain is grey because it is dense with cell bodies and capillaries. The white matter is almost entirely composed of lipid-based myelin, but ...

Turning off depression in the brain

Apr 17, 2014

Scientists have traced vulnerability to depression-like behaviors in mice to out-of-balance electrical activity inside neurons of the brain's reward circuit and experimentally reversed it – but there's ...

Rapid whole-brain imaging with single cell resolution

Apr 17, 2014

A major challenge of systems biology is understanding how phenomena at the cellular scale correlate with activity at the organism level. A concerted effort has been made especially in the brain, as scientists are aiming to ...

User comments

Adjust slider to filter visible comments by rank

Display comments: newest first

JVK
1.6 / 5 (7) Dec 02, 2012
Does extension of an invertebrate to vertebrate model of gene duplications involve the epigenetic tweaking of immense gene networks via the effects of nutrient chemical intake on stochastic gene expression, which is balanced for homeostasis by the metabolism of the nutrients to species specific pheromones that control reproduction? If so, mutated or damages genes that impaired higher mental functions would be selected against at the same time organisms from microbes to man selected for the nutrient chemicals responsible for individual survival as their conspecifics controlled species survival (via pheromone controlled reproduction). How do mutations -- at any time during adaptive evolution -- positively contribute to the required ecological, social, neurogenic, or socio-cognitive niche construction that is nutrient chemical-dependent and pheromone-controlled? Is the model gene to behavior to mutated gene, or gene to behavior and back in species from microbes to man?
Ojorf
4 / 5 (4) Dec 03, 2012
I think you confuse the relative importance of different aspects of heredity. By your reasoning no genetic diseases should exist as they would be selected against, but things are more complex. Single genes have input in multiple expressed traits and there is inevitably a tradeoff, evolution strives to balance these to achieve the greatest gain within the current niche.
But I have no clue, your writing is very confusing.
kevinrtrs
1.3 / 5 (16) Dec 03, 2012
One of the greatest scientific problems is to explain how intelligence and complex behaviours arose during evolution.

Unfortunately, this article and the research does not solve that dilemma in any way.
First of all, it does not reveal how life arose all by itself, purely through random physical activity, without any intelligent intervention in the first place. Unless and until scientists have grip on that particular issue, they have no leg to stand on regarding how intelligence "evolved".
From a philisophical point of view - since they have no idea how life got here, they also cannot make any dogmatic statement as to whether life arrived here already with built-in intelligence or not. This is the achilles heel for any evolutionary thought - the origin of life.
The other is simply the source of information for the requisite building blocks to create the necessary structures needed for the exhibited biological functionality. Plans, specs, etc. Where does it originate from?
Vsha
3.9 / 5 (11) Dec 03, 2012
@kevintrs I don't doubt your conviction, I just believe you are on the wrong site. You are throwing tiny pebbles into a vast ocean of science and hoping to make waves. It just ain't gonna happen.
Torbjorn_Larsson_OM
4 / 5 (8) Dec 03, 2012
Creationists shouldn't comment on science. It is hilarious to see.

@ Vsha: Creationists aren't even interacting with the science.

This specific nut goes on how the origin of life affects todays biology - it doesn't. Luckily, or medicin would be impossible.

The good thing is that creationists help people leave religion. Dawkins' Convert Corner has many tales on how creationists specifically makes people react on their ludicrous notions of how reality works!

Me, I'm having fun watching both how inept they are with science and how inept they are with religion, as counterproductive as it is.
Tausch
1 / 5 (5) Dec 03, 2012
There is no satisfactory transition between a physical source or event and whatever meaning one is able to assign the labels and words 'intelligence' and/or 'thought'.

The vocabulary of the article and Prof. Grant is a disservice to understanding.

Simply name the genes that are asserted to be 'extra'. Let the rest of the community decide if the said genes are the genes Prof. Grant attributes to the 'properties' and outcomes he asserts.
Osiris1
1 / 5 (5) Dec 03, 2012
So THA-A-a-a-a-tts why most of my college profs that were really brilliant and really nice to have as profs...were kinda nutz! It seemed for a long time that being really intelligent and having a PhD came along with being a little nutz and sometimes hung up on 'feces'. Really had some profs that were fascinated by dung, especially human dung. Could not understand why. So Nooooowwww we know!
aroc91
2.3 / 5 (3) Dec 03, 2012
Unfortunately, this article and the research does not solve that dilemma in any way.
First of all, it does not reveal how life arose all by itself, purely through random physical activity, without any intelligent intervention in the first place. Unless and until scientists have grip on that particular issue, they have no leg to stand on regarding how intelligence "evolved".
From a philisophical point of view - since they have no idea how life got here, they also cannot make any dogmatic statement as to whether life arrived here already with built-in intelligence or not. This is the achilles heel for any evolutionary thought - the origin of life.
The other is simply the source of information for the requisite building blocks to create the necessary structures needed for the exhibited biological functionality. Plans, specs, etc. Where does it originate from?


Ban this nutcase already, mods. Do your job. Almost everything he's ever posted has blatantly broken comment guidelines.
Surly
3 / 5 (2) Dec 03, 2012
Simply name the genes that are asserted to be 'extra'. Let the rest of the community decide if the said genes are the genes Prof. Grant attributes to the 'properties' and outcomes he asserts.

The Dlg gene family. Invertebrates have one Dlg gene, most vertebrates have 4. In the study, they put knockout mice with Dlg mutations through a few cognitive tests. The biggest effect they found was with Dlg2, a gene already known to be associated with schizophrenia.

They then compared the Dlg2- mice with four humans who have Dlg2 copy number variations, three of whom also have schizophrenia. Mice and humans with Dlg2 mutations performed significantly worse on all areas of the cognitive test.

Since "Gene linked to mental illness is also linked to poor cognition" would be a boring headline, Grant phrased his statement to imply the reverse.
http://www.nature...276.html
Tausch
2.3 / 5 (3) Dec 04, 2012
Thks Surly.
I relied on the article report here, not the original.
Victimized by popular press reports.
Since there is no excuse not to read the original the rating reflects my neglect - although the people rating me have never rated me higher anyway regardless of I am neglectful or not.
Tausch
1 / 5 (2) Dec 04, 2012
of=if
(typo correction for the last sentence above.)
Pattern_chaser
not rated yet Dec 12, 2012
No point or need to evaluate my Creationist or Darwinist credentials. Does what I say have merit? That's all that matters. In this case, I don't think the article is all that exciting. 4 out of 10, on my score sheet.