Charles Darwin published The Origin of Species in 1859 and introduced natural selection to explain how life evolved. The starting point of Darwinian evolution is random errors committed by nature while copying the DNA during reproduction. This is how small genetic variations occur. These small variations cause differences in eye colour, height, physical characteristics, immunity levels to certain viruses etc. This also explains inherent conditions such as poor cardiovascular health, hereditary disorders, and other conditions that have an adverse effect on life expectancy.
Modern medicine has come a long way in offsetting some of the challenges that genetic variations randomly create, but this was not the average human experience even as recent as 30 years ago. For a large part of human history, the seemingly simple natural selection defined how species competed, survived, and reproduced.
Natural selection is nature on auto-pilot. Life evolves, heads in a direction towards survival, and does not require any deliberate adaptation within the rules of ‘selection’. It has the semblance of a self-contained system where the means for survival is available to the species without active participation.
Except, this is not entirely representative of the situation. Here are two examples that may seem random but I assure you are related.
Example 1 – Thomas Hunt Morgan in 1917, before his Nobel Prize in Medicine for his work with chromosomes and heredity, studied the transformation of caterpillars into butterflies under red, green, or blue light or total darkness. When the metamorphosis was complete, he observed that exposure to red light resulted in butterflies with intensely coloured wings, green light resulted in dusky wings, and blue light or darkness resulted in paler wings.
Example 2 – The human adult body could not digest raw milk from cows about 10,000 years ago. Babies, however, could and by the time they hit adolescence, they lost the ability to break down the enzyme due to gene suppression. When our ancestors started cultivating their own crop, they began to domesticate cattle. Descendants from populations that have traditionally practised cattle domestication have a higher lactose tolerance well into their adult years. Tolerance is higher in Northern European populations (Swedes and Danes at > 90%) and decreases in frequency across Southern Europe and the Middle East (~50% in French, Spanish, and pastoralist Arab populations). These individuals developed a genetic trait for tolerance that was inherited by their offsprings for thousands of years.
The first is an example of change in environment affecting gene expression of species and the second illustrates how a presumably suppressed genetic trait (that gives the amazing ability to digest milk) is reactivated and passed along over generations.
Specifically in the latter, research suggests that human adults developed a lactose tolerance as an evolutionary advantage. The first farmers came to Northern Europe from the Near East approximately 8,000 years ago. Shorter growing seasons compared to southern Europe and the Mediterranean meant the crops they were used to cultivating such as wheat and barley, failed and caused widespread famines. Milk drinking is purported to have increased during these times. The ones with a higher tolerance survived and passed along their genes, while the others died of starvation. Extremely high levels of selection occurred over a relatively short period of time.
This brings me to the lead characters of this post – Jean-Baptiste de Lamarck (1744-1829) and James Mark Baldwin (1861-1934).
Lamarck was a contemporary to Charles Darwin and made notable contributions to biology, including being the first to use the term biology. He is remembered for his evolutionary theories on ‘use and disuse’ and ‘inheritance of acquired characteristics’, dubbed as Lamarckism. Lamarck essentially suggested that species develop traits that they use repeatedly, lose the ones they don’t, and pass on what is acquired to its offsprings.
Lamarck’s views on evolution were overlooked or refuted in favour of Darwinism, on grounds that his positions on use and disuse as well as inheritance are not mutually exclusive to natural selection. (Additional points of contention are elaborated in the post-script) Darwinian evolution was also untouchable during these times, although Darwin himself admitted to being unable to fully explain the rapid changes in traits, towards the end of his career.
Lamarck, in my view, was on to something fundamental – that creatures are remarkably well-adapted to the environments they are born into and continue to adapt through their lived experience.
Baldwin was a lot more than a biologist, with contributions to philosophy, psychology, and psychiatry. The Baldwin effect, posthumously (and controversially; explained in post-script) coined in 1953, suggests “If a species is evolving in a changing environment, there will be evolutionary pressure to favour individuals with the capability to learn during their lifetime.”
For example, if a new predator appears within an environment, individuals that learn the ability to evade the predator will be more successful than the ones that cannot learn. That is, if individuals relied only on their rather rigid genetic composition, they would be at a relative disadvantage. Makes sense, right?
Darwin’s theory of natural selection explains evolution of species over a large period of time. This helps us understand how nature magnificently sets up systems to allow for continuity of life, encodes resilience within its core, and enables those that adapt to improve their lived experiences. Its relevance to understand evolution is quite significant if it is from the perspective of all life on earth.
However, from a human and an individual perspective – for you or me – Lamarck and Baldwin deserve more attention. Recent research affords credence to portions of Lamarck’s and Baldwin’s theories and it is safe to say that this attention is not misplaced. The Baldwin effect especially raises interesting aspects about the role of learned behaviour in evolution. Can we learn to adapt to environmental changes and evolve? While the theory is coherent, there is intense debate about the empirical prevalence of the Baldwin effect at scale and evolutionary biologists aren’t fully convinced, pending further research.
I cannot credibly answer if evolution is just nature on auto-pilot. However, given humans developed consciousness, I would like to believe that we have a bigger role to play in improving our lived experiences. Consciousness helps up evolve. For better or for worse, we certainly are different from who we were at different points of time in our own lives. These changes that we make to our temporal selves are initiated with the generally positive notion that it will serve us better over our lifetime.
I am reasonably convinced and inspired by the idea that my intra-generational learning will serve me well during my lifetime, and possibly help the generations to come. I will rather side with Lamarck and Baldwin than to tether my fortunes to my genetic composition, something that I have no control over.
It is stoic, after all, to only attempt to control what one can.
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Intriguing and/ or interesting developments since the post
#1/ Darwin’s Arch in the Galapagos Islands unfortunately collapsed into the sea due to natural erosion
#2/ An experimental treatment has partially restored visual function in a patient using a combination of optogenetics, gene therapy, and some specially designed goggles.
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P.S. (which is almost as long as the post)
This post was incredibly hard to edit and stitch together, although I thoroughly enjoyed the process. The names of evolutionary biologists mentioned here are rather divisive figures. I hope to elicit some aspects of the debate through this post script.
Darwinism is undoubtedly the overarching framework in evolutionary studies. His work, however, was before the discovery of DNA and subsequent evidence that showed changes to individual traits without changing the genetic composition, a cornerstone to Darwin’s theory.
Conrad H. Waddington coined the term epigenetics in 1942 after conducting a series of experiments on fruit flies. He induced changes or mutations to the fruit flies, remarkably within a single generation, by exposing them to heat. He went on to treat flies over a few generations to have the mutations ‘assimilated’. Offsprings exhibited these traits without the heat exposure subsequently. Epigenetics also explains the ability to digest raw milk among certain adults.
This led to the distinction between phenotype (observable traits such as height, eye colour and blood type) and genotype (genetic characteristics). Certain phenotypes are determined by genetic contribution, but not all. There began the controversy.
‘Between the phenotype and genotype falls the shadow.’ – Eminent biologist Jonathan B L Bard paraphrasing T S Eliot. Let us park that for a moment.
There is an infamous giraffe reference in evolutionary studies.
According to Lamarck, the giraffe got its long neck because its ancestors stretched their necks to eat leaves that were just out of reach. This stretching of the neck was passed on to their offspring, over generations, until it reached its current length.
Darwin’s version would read something along the lines of – there were many giraffes, some with long necks and some with short necks. The ones with the longer necks survived because they could reach the tree tops. The others did not.
While the difference between the two theories is evident, neither could be proved credibly. Darwin’s theory won by popular vote, because of a larger consistency with existing evolutionary discourse. Natural selection is still very much the key contributor in both the versions, it is just a question of when it occurs.
The biggest drawback in Lamarck’s version is that these changes get assimilated rapidly and is inherited in offsprings almost instantaneously. A direct inference of which would be the said giraffe and other lucky ones elongated its neck over a single lifetime. In the interest of full disclosure, there is an additional nuance to this controversy with the suggestion that Lamarck’s language sometimes lacked the clarity that one has come to expect from scientific writing today. Nobody can fully tell what he meant.
Baldwin is a whole different subject. There is an entire book published by the MIT Press that dissects the Baldwin effect. It is basically an anthology of chapters written by eminent evolutionary biologists tracing the historical evolution of the definition (yes, the definition apparently evolved), arriving at the relevance of the original definition to evolutionary research thus far, and whether or not it will continue to be relevant for future research. Needless to say, there are Baldwin Boosters, Baldwin Skeptics, and everyone else in between.
A singular ray of hope in all of this research and writing about the topic is the existence of one theory that brings a lot of these polarising elements together.
The Unified Evolution Theory proposed by Michael Skinner and others. There are two parts to this theory –
— Environmental epigenetic alterations promote genetic mutations to alter genotypic variation.
— Environmental epigenetics and genetic mutations both promote phenotypic variation on which natural selection acts
Let us break this down. While Darwin’s theory starts with ‘random errors’ in gene copying during reproduction, unified evolution theory starts with gene activation or suppressions caused by the environment. The theory suggests that these alterations promote changes to the fundamental genetic composition of species. That’s the first part.
The second part suggests that both these changes – change in gene activity as well as the genetic composition – ultimately promote development of observable traits and then let natural selection run its course.
Needless to say, even this unified theory is far from unifying evolutionary biologists.
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