Darwin’s theory that genetic mutations are always random is wrong, suggests a new study which found evidence that mutations can be a response to environmental pressures.
For more than a century, scientists have held to Charles Darwin’s theory that all genetic mutations are random and accidental, with the most beneficial traits being passed on through the generations of breeding.
Researchers from the University of Haifa in Israel say that isn’t the case, finding that the generation of the human hemoglobin S (HbS) mutation is not random.
People with this mutation have an extra level of protection from malaria, and the team found those in Africa are much more likely to have it than those in Europe.
Study authors say the mutation is not random, as it exists preferentially in Africa, where the protection is more needed, ‘something Darwinism can’t explain’.
‘We hypothesize that evolution is influenced by two sources of information: external information that is natural selection, and internal information that is accumulated in the genome through the generations and impacts the origination of mutations,’ explained Professor Adi Livnat, study lead author.
This new study, including experts from Ghana, is thought to be the first evidence of ‘nonrandom mutations’ in human genes.
The findings challenge a core assumption at the heart of Darwin’s theory of evolution, showing that a long-term directional mutation response to environmental pressures is possible, and that mutations are not just random phenomena.
‘For over a century, the leading theory of evolution has been based on random mutations,’ said Professor Livnat.
‘The results show that the HbS mutation is not generated at random but instead originates preferentially in the gene and in the population where it is of adaptive significance.’
He suggests that evolution is in fact influenced by two sources of information.
These are external information that is natural selection, and internal information that is accumulated int he genome through the generations.
This second type develops through the generations, and impacts the origination of mutations, according to the researchers.
Darwin told us that life arose by evolution, but exactly how the evolution – at the most granular level – actually works, has been open to discussion and debate.
It has long been assumed it was based on a series of accidental changes to the genome, that through natural selection, saw the strongest mutations survive.
For example, under traditional theories, accidents that lead to larger brains are likely to be passed on, but accidents that cause earlier death, are not.
For example, these accidental mutations led to the hawk developing a sharp eye, to help in the search of prey, and the human cardiovascular system or walking upright.
The big problem with this theory was in the area of ‘complexity’, according to Professor Livnat, raising questions over whether the accumulation of small, random changes, can create the level of complexity we see in the world around us today.
While each random change might be beneficial, within the millennia timespan, can they interweave complex parts, such as brains, eyes or even wings?
To distinguish between random mutation and natural selection, and adding in the possibility of nonrandom mutations, Professor Livnat created a new method.
This allowed them to detect de novo mutations, which arrive ‘out of the blue’ in offspring without being inherited from either parent.
The method let them count de novo mutations for particular points of interest within the genome – something not previously possible in such fine detail.
Previous studies have only tested for an immediate mutational response to environmental pressures, and has been limited to measuring mutation rates as an average across a number of positions within the genome.
‘Contrary to the widely accepted expectations, the results supported the nonrandom pattern,’ the research team wrote.
The HbS mutation originated de novo much faster than expected from random mutations, but also much faster in the population. They also evolved faster in the gene where it is of adaptive significance.
‘The results suggest that complex information that is accumulated in the genome through the generations impacts mutation, and therefore mutation-specific origination rates can respond in the long-term to specific environmental pressures,’ said Professor Livnat.
‘Mutations may be generated nonrandomly in evolution after all, but not in the way previously conceived.
‘We must study the internal information and how it affects mutation, as it opens the door to evolution being a far bigger process than previously conceived.’
He said the findings have the potential to change our fundamental understanding of evolution, and diseases that are caused by mutations – including cancer.
This is the second study since the start of the year to suggest nonrandom mutations could be possible, the first looked at a common roadside weed, rather than humans.
In that earlier study, experts from the University of California, Davis, discovered the plant, thale cress, could shield the most essential genes in its DNA from changes.
‘The idea of random mutation has been around for over a hundred years in biology and is something you hear so often as a student that it is easy to take it for granted,’ lead author Grey Monroe told LiveScience.
‘Even as a practicing geneticist and evolutionary biologist, I had never seriously questioned the idea.’
He hasn’t claimed their discovery discredits the theory of evolution, and both studies suggest randomness still plays a big role in mutations, however, it isn’t the only mechanism at play in evolution.
‘In genes coding for proteins essential for survival and reproduction, mutations are most likely to have harmful effects, potentially causing disease and even death,’ Monroe said.
‘Our results show that genes, and essential genes in particular, experience a lower mutation rate than non-gene regions. The result is that offspring have a lower chance of inheriting a harmful mutation.’
Source: Mail Online