Evolution by natural selection is the main evolutionary process by which we explain the diversity of all living organisms. This process is somewhat blind. In simple terms, organisms that are better adapted to their environments are more likely to survive and pass on their genes that aided that successful adaptation (which can also include reproductive abilities).
The blind part (though the environment does guide the whole process) concerns the genetic mutations as genes are copied—rather like a photocopier that makes the occasional mistake by random. Beneficial mutations (mutations that bring about beneficial properties to the organism) that favor its survival are more likely to be passed on as the organism has a better chance of surviving past reproduction (or is more successful at reproduction). Deleterious mutations—ones that give the organism less chance of surviving or reproducing—are weeded out as they are more likely to fail to be passed on as the organism dies before reproductive age or fails to reproduce.
This process, over successive generations, predominantly (as there are other mechanisms such as genetic drift) accounts for the diversity in all living organisms.
But this has not always been the only evolution theory in town. There was another, but it was run out a long time ago.
And now the saloon doors might just have been thrown open again.
Where evolution by natural selection, though it is driven and “directed” by evolutionary forces and pressures (such as the environment shaping the changes of organisms), there was no sense of mechanisms “driving towards” a given end.
I am not talking about agency here, and certainly not God, but I might have to mention the doctrine of Lamarckism in evolution, now long discredited.
The theory was proposed by French naturalist Jean Baptiste Lamarck in the 1800s. We might consider the example of a blacksmith with burly arm muscles, or a musician with dexterous fingers and hands. These characteristics would not find their way into the genetic code of the individuals’ offspring since they are responses to the environment and are ways that the bodies are altered at a biological as opposed to a genetic level. This is sometimes called “soft inheritance” or “inheritance of acquired characteristics.” Such a theory would see giraffes growing longer necks because they are constantly striving to reach higher plants, rather than long necks being evolved after consistent advantageous but random mutations to the neck that just so happened to benefit the giraffe, both as an organism and as a species.
Recently, there have been areas that look similar to Lamarckism, such as epigenetics. Rather than passing on altered genes across generations, epigenetics looks at how other hereditary elements can be passed on, such as when proteins are released in gene regulation. Though the genes themselves may not be changed, when and how they are expressed can be, and these elements can pass across generations.
But in terms of genetic alteration, Lamarckism has been on the back foot for almost a century.
However, new research just published in Genome Research by scientists from Israel and Ghana seems to indicate directionality and nonrandom mutation in genetics.
Welcome back Lamarckism?
Using a new research method, the team looked at malaria resistance being higher in people in Africa, where the disease is prevalent, versus in Europeans, where it is not. Lead researcher Professor Adi Livnat from the University of Haifa said,
“For over a century, the leading theory of evolution has been based on random mutations. 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.”
This is, of course, potentially very big news. He continues:
“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.”
This may come as either a relief to some, or no surprise to others, since there are many people who intuitively grapple or struggle with the idea that such rich complexity can come about through simple “blind chance,” even given the framework of evolutionary pressures. Perhaps evolution by natural selection, genetic drift, epigenetics, other such mechanisms, and some kind of directional evolutionary mechanism can account for biological diversity even better!
Phs.org (from the University of Haifa press release) explains the novel method employed by Livnat and his team:
In order to distinguish between the random mutation and natural selection explanation and the possibility that nonrandom mutation is important, Prof. Livnat and his lab manager, Dr. Daniel Melamed, developed a new method for detecting de novo mutations—mutations that arise “out of the blue” in offspring without being inherited from either parent. In breaking a new accuracy record, their method allowed something not previously possible—counting of de novo mutations for particular points of interest in the genome.
They then applied their method to examine the de novo emergence of the human hemoglobin S (HbS) mutation, perhaps the most well known point mutation in biology and evolution. HbS provides protection against malaria for people with one copy but causes sickle-cell anemia in those with two. Malaria itself, a vector-borne blood disease, has arguably been the strongest selection pressure acting on humans in the last 10,000 years, often causing more than a million deaths per year in Africa in the recent past. HbS is also used as a central example of random mutation and natural selection in evolution: It has been long assumed to have arisen accidentally in an individual in sub-Saharan Africa and then spread inside Africa via natural selection until its malaria-protective benefits were balanced out by its sickle-cell anemia costs.
By examining the de novo origination of HbS, Livnat was able to disentangle for the first time whether the malaria-protective mutation arises randomly and spread in Africa only because of selection pressure or instead whether it could actually be originating de novo more frequently in sub-Saharan Africans—a group that has been subject to intense malarial selection pressure for many generations. If the mutation is random, then it should be equally likely to emerge in both geographical groups. However, if mutation is nonrandom, then perhaps it would actually emerge more frequently in Africans.Study uncovers first evidence of long-term directionality in origination of human mutation, challenging neo-Darwinism, Phs.org – University of Haifa press release.
The results they gathered supported the nonrandom pattern and hypothesis. But it looks like rather than being a Lamarckian hypothesis outperforming one of natural selection, the results show an odd synthesis of the two:
Contrary to the widely accepted expectations, the results supported the nonrandom pattern. The HbS mutation originated de novo not only much faster than expected from random mutation, but also much faster in the population (in sub-Saharan Africans as opposed to Europeans) and in the gene (in the beta-globin as opposed to the control delta-globin gene) where it is of adaptive significance. These results upend the traditional example of random mutation and natural selection, turning it into an example of a nonrandom yet non-Lamarckian mutation.
“Mutations defy traditional thinking. 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 Prof. Livnat. Previous studies, motivated by Lamarckism, only tested for an immediate mutational response to environmental pressures. “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,” Livnat concluded.
This is definitely fascinating stuff because it could properly challenge received wisdom about how evolution works (though it doesn’t remotely do what some evolution denialists think it might do).
Author’s note: One iteration of the press release did state that the research was made possible by funding from the John Templeton Foundation, an organization that seeks to promote the intersection of religion and science. This is not to poison the well per se, but it is worth noting.