Teens with fluctuating IQ, and worms that inherit a "memory of longevity"

By Ed Yong | October 19, 2011 7:33 pm

This week, I’m filling in for one of the Guardian’s science correspondents (the excellent Alok Jha), and I’ve been asked to cover a few stories that I would otherwise do here. So, let me direct you to the Guardian website where you’ll find the two pieces I filed today.

Worms can inherit a ‘memory of longevity’ from long-lived parents

Long-lived worms can transmit their extended lifespan to the next generation by passing on changes in the way their genes are used, rather than differences in DNA itself.

A study has shown that nematode worms can inherit a “memory of longevity” from their parents, even though their genome remains unchanged.

It is not clear if the same processes apply to humans, but Anne Brunet from Stanford University, who led the study, noted that some genes that affect the lifespan of nematodes were later found to influence human longevity too. “In several cases, the worm has proved to be a good model for humans, who live 2,000 times longer,” she said.

Her team is now looking to see if the results in the worm Caenorhabditis elegans translate to species that are evolutionarily closer to humans, such as fish and mice.

The discovery is an example of “epigenetic inheritance”, where organisms pass on changes in the way genes are used rather than in the genes themselves. As animals develop, their DNA and proteins become annotated by molecular marks that act like Post-It notes, dictating which genes are read without changing the underlying text. The marks are meant to be stripped away with each new generation, but some stay behind.

[I'm glad the editors kept the bit at the end where I patiently explain why epigenetic inheritance isn't some sort of death knell for Darwinian evolution, and, in fact, fits snugly within it]

Teenagers’ IQ scores can rise or fall sharply during adolescence

IQ scores can change dramatically in teenage years in parallel with changes to the brain, according to a study that suggests caution in using the 11+ exam for grammar school entrance to predict academic ability.

IQ is thought to be stable across a person’s life. Childhood scores are often used to predict education outcome and job prospects as an adult. But the study suggests scores are surprisingly variable.

Robert Sternberg from Oklahoma State University, who studies intelligence but was not in the research team, said: “A testing industry has developed around the notion that IQ is relatively fixed and pretty well set in the early years of life. This study shows in a compelling way that meaningful changes can occur throughout the teenage years.”

Our mental faculties are not fixed, he said: “People who are mentally active and alert will likely benefit, and the couch potatoes who do not exercise themselves intellectually will pay a price.”

[Note: Redundant headline is redundant. I don't write 'em]

Comments (7)

  1. Cathy

    IQ tests can be practiced just like any other type of test. I did logic problems (crosshatch grids and related ones published in the Dell magazine) as a hobby all throughout high school. I even made my own cross hatch grid once as a school project. That practice helped me out years later when I took the GRE, scoring 790/800 on the analytical portion before they switched it over to writing, and then surprising quite a few job recruiters who gave logic tests by actually finishing them and getting them mostly right. I still take IQ tests for fun, but because I switched my hobby from logic problems to cross stitch after I got married, I’m sure my IQ has “dropped” because I’m really rusty now.

  2. JL

    Who actually thinks that IQ cannot rise or fall sharply during adolescence? The Deary et al. paper you linked to certainly does not support such a notion. No one thinks that IQ is “fixed”. It can change both due to actual changes in ability and due to training effects that affect test scores but not ability.

  3. Jay Derrick

    If intelligence varies over time, or if it is multiple, as Howard Gardner and others argue, or if as Cathy points out, it can be raised through practising for tests, then why do we talk about it at all? The concept of intelligence has far more historic significance as a stick with which people have been beaten, and which divisive or even murderous social policies have been based on, than as a useful way of understanding human capacity. As a measurable quantity it was orginally modelled by Binet, who wanted to justify extra expenditure on the education of people with learning difficulties. But it was only ever a model, not an actual quality (and certainly not a fixed quantity) of human physiology. Common sense tells us that different people perform differently at different times and under different circumstances, and that these differences are often merely a product of the testing regimes used. This was all dealt with decisively in my view years ago by Stephen Jay Gould, in ‘The Mismeasure of Man’, which demolishes the pseudo-science of IQ theory.

  4. JL

    Jay, Gould’s book is garbage. It has more errors of fact and interpretation per page than probably any other book I’ve read. If you want to know about IQ, you should read someone who is an actual expert on the topic.

  5. AG

    Is intelligence difference between human and rat due to genetic or enviromental factor? If answer is genetic, the genes have clearly estabolish as important factor in mental ability, at least among different speciese. The next question is how much genes contribute to difference of human mental ability. Denial of such genetic component is obviously wrong.

    We all have no issue with human height as gene expression. Enviroment is equally important for human height. But genetic factor is no doubt. The same should apply to mental ability.

  6. James

    Gardner’s theory has no empirical evidence behind it.

  7. tall blue ape

    umm… weed? ativan? sleep deprivation? of course you can easily change IQ scores….

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