Scientists have proposed a model that shows human extinction is not just a matter of climate change, but of an “epigenetic” change.
The new model shows how a mutation in a gene called TERT1, which is linked to a key protein in the body, could lead to an irreversible decline in human intelligence.
“It is now clear that our genome is a living organism, and that its evolution has occurred with the same rapidity that other species have,” Professor James Oakeshott, from the University of York, told The Independent.
The model was based on a combination of genetic data and behavioural experiments, which showed how an individual’s genetic changes over time lead to changes in their behaviour.
The researchers concluded that if this gene mutation leads to the rapid decline of intelligence, it would have to be accompanied by a loss of a key cellular component, called the telomere, which keeps the ends of chromosomes together.
TERT1 has been implicated in ageing, and is known to have been involved in regulating the function of proteins known as telomerase.
But if the mutation was to cause a gradual decline in intelligence, the researchers believe this would not be because of an impairment of telomeric DNA, but instead a loss in telomeres.
That would imply that it would be a natural process, the model said.
“We believe that there are some plausible mechanisms for the observed declines in intelligence,” said Dr Oakesmott.
If the mutation could lead directly to the decline in telomeras, it could affect the functioning of more than just the telomerases, he said.
While this mutation would not directly affect intelligence itself, the loss of the telomesome could make a person less likely to develop mental retardation.
This could potentially have profound consequences for the way in which the brain is organised and functioning, he added.
Dr Oakeswott said he had been inspired by the work of the scientists who have found a similar mutation in humans that causes a similar decline in cognition, and has been working to develop new methods to map this process.
“I have been studying the ageing process, and I was struck by how little we understood about how these processes actually work,” he said, adding that the work would provide insight into the genetic causes of cognitive decline.
Professor James Oakehott said that while the model was not entirely new, it is the first to use genetic data to map how this process works.
Although this study is a first step towards understanding the causes of the decline of cognitive ability in humans, the findings could help scientists understand how we have evolved, he told The Guardian.
A similar study, which was published in Nature Communications in May, found that a mutation of the TERT gene causes a decline in cognitive abilities in people with Down syndrome.
For many years, scientists believed that genetic factors were the primary drivers of this decline, with studies linking the genes with specific traits.
However, the discovery of the mutation has led to the hypothesis that the cause of the brain’s decline may lie elsewhere, leading to a lack of gene regulation.
In the latest study, the scientists were able to find evidence of a loss-of-function mutation in the telomysome, which they believe is responsible for this loss of control.
According to Professor Oakeswa, this could lead researchers to develop a new method to map the gene’s function.
Scientists have also found a mutation known as SLC19A2, which can lead to the loss- of-function of the body’s immune system, which makes it more susceptible to infections.
As we age, this can lead directly or indirectly to many different diseases, such as asthma, Alzheimer’s, stroke and cancer.
Prof Oakesham also believes that it is not yet clear how the loss in intelligence could be caused by a decline of the immune system.
He believes that the loss could be due to the weakening of immune function caused by ageing, rather than a loss caused by genetic changes.
“It could be a loss, because it is a loss that is caused by the ageing of the human body,” he told BBC News.
“There is no obvious reason why the immune cells would stop functioning.
If we don’t know what the cause is, we cannot make a diagnosis.”
“What we do know is that ageing has a huge impact on the immune systems, and the immune functions that the immune cell makes have changed,” Professor Oakeweth said.
“It has become more difficult to recognise when we have an infection or an infection is the cause.
It is also becoming harder to recognise how that infection affects the immune function.”
If there are a few other factors that cause a decline, such an illness or a combination, then this might be the cause, he explained.
These include the aging of the cell, which leads to more and more cells dividing.
And the ageing also means that