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.
Darwin’s theory that genetic mutations are always random is wrong, a new study suggests, finding evidence of mutations in response to environmental pressures. Stock image
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.’
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. Stock image
DNA: A COMPLEX CHEMICAL THAT CARRIES GENETIC INFORMATION
DNA, or deoxyribonucleic acid, is a complex chemical in almost all organisms that carries genetic information.
It is located in chromosomes the cell nucleus and almost every cell in a person’s body has the same DNA.
It is composed of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).
The structure of the double-helix DNA comes from adenine binding with thymine and cytosine binding with guanine.
Human DNA consists of three billion bases and more than 99 per cent of those are the same in all people.
The order of the bases determines what information is available for maintaining an organism (similar to the way in which letters of the alphabet form sentences).
The DNA bases pair up with each other and also attach to a sugar molecule and phosphate molecule, combining to form a nucleotide.
These nucleotides are arranged in two long strands that form a spiral called a double helix.
The double helix looks like a ladder with the base pairs forming the rungs and the sugar and phosphate molecules forming vertical sidepieces.
A new form of DNA was recently discovered inside living human cells for the first time.
Named i-motif, the form looks like a twisted ‘knot’ of DNA rather than the well-known double helix.
It is unclear what the function of the i-motif is, but experts believe it could be for ‘reading’ DNA sequences and converting them into useful substances.
Source: US National Library of Medicine
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.
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, that protects against malaria, which is spread by female mosquitos, is not random
WHAT IS MALARIA? A LIFE THREATENING TROPICAL DISEASE
Malaria is a life-threatening tropical disease spread by mosquitoes.
It is one of the world’s biggest killers, claiming the life of a child every two minutes, according to the World Health Organization (WHO).
Most of these deaths occur in Africa, where 250,000 youngsters die from the disease every year.
Malaria is caused by a parasite called Plasmodium, of which five cause malaria.
The Plasmodium parasite is mainly spread by female mosquitoes.
When an infected mosquito bites a person, the parasite enters their bloodstream.
- Feeling hot and shivery
- Muscle pain
These usually appear between a week and 18 days of infection, but can taken up to a year or occasionally even more.
Malaria is found in more than 100 countries, including:
- Large areas of Africa and Asia
- Central and South America
- Haiti and the Dominican Republic
- Parts of the Middle East
- Some Pacific Islands
A blood test confirms a diagnosis.
Source: NHS Choices
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, speaking to JPost.
‘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.’
The findings have been published in the journal Genome Research.
CHARLES DARWIN: THE BRITISH NATURALIST WHO INTRODUCED THE IDEA OF NATURAL SELECTION
Pictured: Naturalist Charles Darwin (1809-1882)
Charles Robert Darwin was born in Shrewsbury, Shropshire, the fifth of six children of wealthy and well-connected parents.
One of his grandfathers was Erasmus Darwin, a doctor whose book ‘Zoonomia’ had set out a radical and highly controversial idea, that one species could ‘transmute’ into another. Transmutation is what evolution was then known as.
In 1825, Charles Darwin studied at Edinburgh University, one of the best places in Britain to study science.
It attracted free thinkers with radical opinions including, among other things, theories of transmutation.
Darwin trained to be a clergyman in Cambridge in 1827 after abandoning his plans to become a doctor, but continued his passion for biology.
In 1831, Charles’ tutor recommended he go on a voyage around the world on HMS Beagle.
Over the next five years Darwin travelled five continents collecting samples and specimens while investigating the local geology.
With long periods of nothing to do but reflect and read, he studied Charles Lyell’s Principles of Geology, which had a profound impact.
The trip also began a life of illness after he suffered terrible sea sickness.
In 1835, HMS Beagle made a five-week stop at the Galapágos Islands, 600 miles off the coast of Ecuador.
There, he studied finches, tortoises and mockingbirds although not in enough detail to come to any great conclusions.
But he was beginning to accumulate observations which were fast building up.
On returning home in 1838, Darwin showed his specimens to fellow biologists and began writing up his travels.
It was then that he started to see how ‘transmutation’ happened.
He found that animals more suited to their environment survived longer and have more young.
Evolution occurred by a process he called ‘Natural Selection’ although he struggled with the idea because it contradicted his Christian world view.
Having experienced his grandfather being ostracised for his theories, Darwin collected more evidence, while documenting his travels, until 1851.
He decided to publish his theory after he began to suffer long bouts of sickness.
Some historians suggest that he had contracted a tropical illness while others felt that his symptoms were largely psychosomatic, brought on by anxiety.
In 1858, Darwin received a letter from Alfred Russel Wallace, an admirer of Darwin’s from reading about his Beagle Voyage.
Darwin was criticised by the Church and some of the press as people were shaken by the idea that humans descended from apes
Wallace arrived at the theory of natural selection independently and wanted Darwin’s advice on how to publish.
In 1858, Darwin finally went public giving Wallace some credit for the idea.
Darwin’s ideas were presented to Britain’s leading Natural History body, the Linnean Society.
In 1859, he published his theory on evolution. It would become one of the most important books ever written.
Darwin drew fierce criticism from the Church and some of the press. Many people were shaken by the book’s key implication that human beings descended from apes, although Darwin only hinted at it.
In 1862, Darwin wrote a warning about close relatives having children, he was already worried about his own marriage, having married his cousin Emma and lost three of their children and nursed others through illness.
Darwin knew that orchids were less healthy when they self-fertilised and worried that inbreeding within his own family may have caused problems.
He worked until his death in 1882. Realising that his powers were fading, he described his local graveyard as ‘the sweetest place on Earth’.
He was buried at Westminster Abbey.