What are the Three Questions of Biology?

If the scientific method for biology were organized around three questions and science after all is about asking questions about nature and biology examines the living aspects of nature, biology should be organized around three questions.

What exactly would be the three questions of biology? According to Mayr (1997) they are the “what” questions, “how” questions, and “why” questions or taxonomic, proximate, and ultimate questions respectively.

Before I talk about those three questions in detail, I should talk about the scientific method and how it applies to biology. As you may know the scientific method is that set of procedures which begins with observation of whatever there is in the natural world, and through observation, you have collection of data, which can either be descriptive or quantifiable and do the data reveal a pattern? Science is generally not just about observations but of finding real patterns that exist in nature. If there are patterns then what are the mechanisms causing the patterns? If patterns are present then one would need to form a hypothesis or a tentative explanations or more simply an education guess which may or may not be true and hypothesis can predict the outcomes which can then be confirmed by experiment.

Experiment is a form of testing and science is about testing the outcome set forth by a hypothesis and this can be done , in a laboratory where a given variable or something that changes can be examined only if certain conditions are fixed and expected outcome may or may not occur. An example of a laboratory experiment in biology would be determining the rate of mutation of a strain of bacteria. Also experiments can be done in the field such as tracking a wild animal using radio collars to determine where it may be in the wild.

Biology is not only an observational science such as observing birds in their habitat for example but also an experimental science. Indeed whenever an experiment is performed whether in the lab or in the field, observation will always be present and with that data collection and if a pattern emerges then finding a mechanism that can be tested if the same pattern can be repeated then the same pattern is likely to account for what the proposed mechanism predicts and so a theory which is a set of testable explanations for a given phenomenon under study which can be tested for certain outcomes. A theory can be broadened to accommodate other explanations which previously were unrelated.

An example is the theory of genetics or the field of biology that studies biological inheritance, which was established as an experimental science by Austrian monk and botanist Gregor Mendel. For about 6 years, while working in a garden, he carefully raised and bred pea plants and he set out to determine the rules for how traits are inherited from parent to offspring and he studied visible traits of pea plants such as flower color, plant height, and pea texture for example and through careful breeding, he found that traits tend to be inherited discretely that is a trait for flower color is inherited through the male and female plant but flower color is either red or white with one color being the dominate in one generation while the other color seem to be absent but in later generations, that color will eventually show it so it has not really disappeared but overshadowed by the dominate color only to appear later. The same pattern of dominance and recessiveness is also true for pea texture, plant height, and so on.

Mendel identified these patterns and in doing so he established the science of genetics as a viable field of biology through careful observation and experiment which is the basis of genetics and the goal of genetics is to investigate the source of biological variations, where it come from, what causes it, and how trait are inherited.

Mendel went a step further and through his experiments, he even hypothesized that these traits come in as discrete, heritable “factors” and each offspring inherits two of these factors from each parents, which of course are called genes and two versions of genes are called alleles but since Mendel only worked with pea plants, is it even possible that what is true for pea plants is also true for all of life? With only pea plants to work with, it was not possible to say with certainty that his rules for inheritance are valid for all of life. Also, if inheritable traits are caused by factors, then what is the nature of these factors or genes. Years later around 1869, a Swiss biochemist Friedrich Miescher isolated a substance from pus which was found in cell nuclei and was called nuclein which was later called nucleic acids. Genes and nucleic acids when both of which were investigated at first seemed nothing to do with one another and in a previous called “The Ever Changing Concept of the Gene”, I showed how a concept in science can change or rather broaden  and that is the concept of the gene changing as new scientific evidence is available, but back to my example of theory and the theory behind genetics is that traits are inherited so these factors or genes were later shown to be molecules of nucleic acids which are molecules of DNA so the same method of investigations of genetics which showed patterns of inheritance in pea plants and later for all forms of life are the result of the double helix which is what a DNA molecule and thus a definition of gene is a section of DNA that codes for proteins which result in the traits and DNA is inherited to the next generation since DNA stores information for proteins as well as how to replicate when the need for reproduction arises.

It is through genetics that Mendel’s factors and Miesher’s nuclein where revealed to be one and the same and countless experiments whether of organisms and molecules confirm this so the theory of inheritance eventually became the fact of heredity and with genetics, Darwin’s theory of evolution by natural selection was also broaden to include changes in genes in a population through Modern Synthesis or the combination of Darwin and Mendel made possible by broadening the investigative scope of genetics and together with observations in the lab and in the field.

This is a good example of a how a theory works. It explains seemingly unrelated facts and reveal them to be aspects of the same thing which can be proven by experiments or also it can be disproven or else modified when new data is available. Of course, there has to be countless testing of the same experiment in order to confirm that what the theory predicts is true or not and theories are something that are not written in stone but can be modified or even replaced if out of many experiments one single outcome turned out to be different and unexpected. It could be that a mistake was made in the experimental process so the same experiment is repeated and either an mistake can be uncovered or the unexpected outcome is real and it could tell us something about the outcome in which if real, the theory making the prediction must be modified or possibly rejected.

Notice that a theory is something precise, is able to make predictions and make connections between seemingly separate facts under a coherent explanation which can be supported or falsified by experiments, and it is not the common use of the word “theory” in everyday language as synonymous with “guess” and theory is anything but “guess” although theories usually start of as hypothesis but are educated guess about the outcome of something which if supported by experiments, then hypothesis usually become theories.

The word “theory” of course has nothing to do with the everyday use of that word, and a classic example of this , usually by opponents of evolutionary theory, the central unifying principle of biology which I will talk about in a future blog, who usually say “evolution is just a theory” which  really does not reveal any deep insight of nature other than showing that they are really demonstrating their ignorance of evolution either based on a faulty understanding of evolution or just plain ignorant of how evolution really works not to mention ignorance of the scientific method but theories do become facts sooner or later and evolution of course through countless observations and experiments is indeed a fact.

I cannot mention before I talk about the three questions of biology that those of a philosophical bent in regards to the science of biology and I have decided to reveal something about biology and that is in regards to the objectives of the biology of science both biology as well as the other sciences such as physics, astronomy, and chemistry both use the scientific method in arriving at theories of how nature works. However because of what biology studies, and although biology always conforms to the scientific method, and because it studies life, it is revealed that biology in a way is a special science that is unique in comparison to physics and astronomy.

What I mean is that biology is a science that studies life but evolutionary theory is a science that is central to biology made possible by the work of Darwin and the Modern Synthesis in that biology is really a historical science and it is part of the “why” questions or “ultimate questions” that is to satisfactorily answer these questions is to rely on evolution. No other theory of life has proven to be so successful than Darwinian evolution and the approach of asking ultimate questions is what sets biology apart from the physical sciences as Mayr (1997) emphasized.

In physics, that science studies matter, energy, and forces at a fundamental level and starting with classical mechanics or the study of particles in motion as established by Isaac Newton, the motions of simple particles can be predicted if one knew their masses, as well as their velocities and through Newton, experiments can be set up to predict the velocities and forces acting on moving particles, small or large.

At the most fundamental level, the forces acting on particles are the same in the past and future so there is no distinction between past and future and hence there is no history where future is different in the past.

However life does have a history and through the science of paleontology or the study of ancient life, the ancestors of extant life is clearly different so the evolution of life proceeds with a definite direction from past to the present which is something that is unknown in Newtonian mechanics.

In addition, biology is characterized by chance process such as mutations and extinctions, none of which can ever be predicted with the same rigor as the equations in Newtonian mechanics.

That is not to say that biology is in some sense, a science that does not conform to the principles of physics and indeed, physics was at first based on the principle of mechanics according to Newton and not just for inanimate systems but animate systems were being placed within a Newtonian framework and through Newtonian mechanics came the principle of reductionism or by treating the system as fundamentally reduced to its essence, which is also the essence of physics, then at the most basic level, systems are nothing but particles responding to blind, mechanical forces.

The reductionistic approach had some moderate success in biology and came sciences such as biochemistry, biophysics, and molecular biology which are based on the reductionism of physics and it was revealed for example that genes are composed of DNA and through techniques originally developed from physics such as x-ray crystallography, nuclear magnetic resonance, and electron microscopy, it was found that DNA stores information and is the only polymer to replicate. This made possibly the maturing of the field of biology, molecular biology by studying the molecular basis of life such as heredity.

Of course reductionism does have its limits in biology and this was already emphasized by biologists of a naturalist bent that is those who focused on whole organisms, their habits, and where there are found and even today, some biologist that practice the science of ethology or animal behavior would not consider replicating molecules as a sole explanation for mating rituals of certain species of birds and likewise when studying the larval cycles of frogs in a pond, there is absolutely no need to consider the position of a single carbon atom in a protein molecule in a given cell of a developing frog.

The fact that organisms develop from a fertilized egg into a viable organism suggests that there is no single atom that can control the full structure of an organism and unlike point particles that just simply respond to external forces, animals as well as plants behave with purpose and from field and laboratory studies there is no denying that fact that behavior is something purposeful.

It was from observations that biologists at one time rebelled from the Newtonian paradigm of mechanical forces and adhered to a philosophy called vitalism or belief that what sets life apart is a mystical magical force that gives life the ability to grow and change something not present in simple material particles. As legitimate as those biologist were in doing so, eventually vitalism turned out to be an unscientific concept. For one thing it makes no predictions that can be verified nor falsified through experiment and that is the basis of a scientific theory whereas vitalism is something that is more for metaphysics but not empiricism which is what science such as biology is really about. Second, there is no hard evidence for a magical “life force” despite appearances for when the techniques of biochemistry and biophysics got more and more refined, no “spark of life” that sets life apart from nonlife was ever found.

Yet, we know now that in a way there is no difference between life and nonlife for life is composed of the same atoms as nonlife but we know that simple physics can never account for the various activities and behaviors of life, rather life as dynamic system is something complex, while physical systems are simple.

Also, life is a process of living but also a historical process for each living being is an unique individual, as a result of heredity and is also the descendant of past individuals and it is through evolution of natural selection that makes biology a unique science in that respect.

Of course, physics is not necessarily a rigorous science based on exact predictions. Starting with the science of thermodynamics and later quantum mechanics, the rigorous and exact Newtonian predictions eventually gave way to randomness and uncertainty, which later turned out to be the rule rather than the exception. If physics was given a probabilistic basis then biology would be in good company in that regard and after all evolution does have chance components but there is only one mechanism that is anti-chance and that is natural selection so both chance and natural selection or rather chance and necessity play a part in the history of the biosphere.

The science of biology combines historical fact of all organisms which is evolution together with a mechanism for how life forms evolve and that is natural selection. Biology still is in league with observations and experiments but with Darwinian theory all the sciences of biology became unified and so with the “what” and “how” questions, biology could now proceed with “why” questions and so without further ado, let us take a look of these questions in detail.

                                         The “What” Questions or Taxonomic Questions

Planet earth is the only planet in our solar system that is known so far with life, both extant and extinct, and there is a huge diversity in the forms and activities of every life form. Small life forms are abundant such as bacteria and protists and large life forms from birds to mammals are also present and each life form occupies every part of the land and oceans. Just what are these kinds of life forms and how do they relate to one another? Before Darwin’s great insight that all of life is one, it was known that each organism is different from one another but also some organisms could be seen to have some things in common or that there are species or kinds of organism and after all, our earliest ancestors had to tell the difference between a living thing that was edible and also a living thing that was poisonous.

From early times until modern times, “what” questions were asked in regards to all the life forms making up this diverse biosphere and there is a field of biology that deals with classification of organisms based on shared characteristics that defines one species from a different species and that is the science of taxonomy.

When asking what organism is being studied, a “what” question would be asking a taxonomic questions and they would be

What kind of organism is this?

Does this organism share characteristics with known species?

Is it a known species or does it belong to a species that is not yet recognized?

Recall that biology is a descriptive science and asking “what” questions is part of the descriptive process which is part of the scientific method for biology.

Once organisms are studied and found to display characteristics in common, the next step is to show any relationship within individuals in a species and also the degree of similarity between species as well as their differences.

The first systematic step in classification and indeed when taxonomy became a true science began with Carolus Linneaus and his binomial system of placing organisms that were described, where it was from, and so on with a species name and genus name such as Drosophila melongaster or fruit fly where Drosophila is the genus and melonogaster is the species name. From genus and species, there is family, that is what do the genera (plural of genus) of various fruit flies have in common based on certain characteristics that all fruit fly species share. What do fruit flies, dragonflies, butterflies, and beetles have in common? All these kinds of organisms have six legs, a head, thorax, and abdomen, and undergo metamorphosis from egg to larvae to pupa to adult, and thus are insects so fruit flies, butterflies, and beetles form a class which are insects. Because insects as well as spiders along with crustaceans all possese jointed legs and an exoskeleton are collectively called arthropods which is an order and from order there is and arthropods belong to the next highest classification, the phylum which is invertebrates or those organisms lacking vertebrae or backbone and invertebrates are at the highest level of classification, animals or organisms that can move and sense because of a nervous system along with a muscular system of various degrees of complexity and can only get food by consuming organic molecules by actively seeking for food.

This is an example of what is called “upward classification” since it begins at the lowest level ( the species) and works upward to the highest level ( the kingdom which is animal kingdom for example). This system of classification as proposed by Linnaeus is still in use, although it was modified as new techniques in biology were being developed which broadened Linnaeus’s original classification scheme while new species of life forms were being discovered.

As useful as this scheme, such as placing organisms within categories for the purpose of identifications, there are noticeable flaws in the framework.

For one thing, when it was developed by Linneaus, originally it was developed for classifying plants since Linnaeus was a botanist by training but eventually his binomial classification applied to animals but when the science of microscopy and thus microbiology as a field of biology was being developed, and with microscopic observations of small organisms that would designated as protists and bacteria , the binomial classification had to be broadened to include bacteria and protists by creating kingdoms separate form the plant and animal kingdom the former the kingdom Monera and the latter, Protista for without such broadening, and with considerations of kingdoms animals or plants, some microorganisms had both characterstics of either plants or animals and for some, both so the classification had to be expanded and revised to keep ambiguity as low as possible.

The foundation of the original proposal of the Linnaen system of classification was that it was based on the morphological concept of species or what individuals in a population had in common that was visible to a discerning naked eye and it was from observations of visible characterstics such as the presence or absence of a backbone for example that the Linnaen system was founded upon.

I wrote in a previous blog “Typology versus Population” that what sets Darwinian thinking apart from previous evolutionary theories is that unlike non Darwinian evolutionary theories such as Lamarckism and orthogenesis is that Darwinian evolution is founded upon population thinking or the realities of the uniqueness of individuals in a population and through reproduction, each individual will be unique and whatever unique phenotype that individual has will make the difference between life or death and that defines genetic variation, such as mutations and recombinations in meiosis allowing for heritable variations which are present in any living population. It is living populations in changing environments where evolution by natural selection is possible.

The morphological species concept is really a typological species concept and the Linnaenan classification scheme is really founded on a typology species and typology or types are things that never change that is a population of fruit flies, flycatchers, or whatever are fixed and unchanging which Darwin revealed are not types but evolving entities.

Since the Linnean classification is really typological that means that none of the species described are evolving and after all Linnaeus himself did not think that species would evolve into different species since he like his fellow scientists were operating within a typological framework at the time, since even scientists, in the western world, believed that all species were created in their present form by God and typology really is about unchanging essence even though with the Linnaen system, and up in higher levels of classifications it is possible to show that seeming different species do share certain characterstics such as beetles and crabs each possessing jointed legs and an exoskeleton not to mention that the same patterns of arm bones are similar in seemingly unrelated individuals of different species of mammals such as the arm bones of chimpanzees, in the wings of bats, in the legs of horses, and the flippers of whales, those same patterns of bones, a classic textbook example of what is called homology, but even with Linnaen classification it would not reveal any pattern of common descent and similarities of anatomical design would be coincidence.

With the publication of The Origin of Species by Darwin who was the first biologist to adopt population thinking and also the first to make “why” questions or ultimate questions part of the scientific method, the classification scheme of Linnaeus would have to give way to a classification scheme that took evolutionary history of all life into account.

With a classification based on evolution, the relations between species were seen as the result of previous generations adapted to previous changes in environments and such a classification would be more natural in that it would be independent of any arbitrary human groupings but would reflect real evolutionary relationships.

Classification as a scientific method is based on description and as long as one accepted typology then any real relationship was not just meaningless but coincidental but with the acceptance of population thinking came first the concept of natural selection then later the reality of natural selection , what classification can now be seen as a historical or evolutionary relationship between all forms of life that are known and have yet to be described.

It is one thing to classify organisms but is quite another to understand the fact that all life forms, big and small do something to make a living , how they develop in their life cycles, and how they deal with what is present in their natural environment. From “what” questions there are “how” questions or proximate questions and these questions ask about the biological mechanism such as development and metabolism and much of biology is devoted to asking proximate questions.

                                                 The “How” Questions or Proximate Questions

Every living thing does what it can to survive but how do they do this? The kind of questions for the functions of organisms are the proximate or the “how” questions. Examples of proximate question are

1. How do migrating birds follow the exact path in flight?

2. How do animals hibernate?

3. How does the metabolism kept constant in an organism in changing temperatures?

and so on. All these questions lead to research on the biological mechanisms and there are various fields of biology that can answer, based on the fact that there are each field of biology that studies a specific problem and that each has its own methodology for obtaining results. Biochemistry and biophysics for example uses the techniques and methods of chemistry and physics respectively to determine which molecules are present in a given biochemical reaction, the structure and function of molecules and how it relates to their activity and which specific set of reactions are responsible for what process is occurring in each organism. On the level of organism there is cell biology and the techniques of this field are based on techniques on biochemistry and biophysics but this field is specialized in the study of cells and the proximate questions for cell biology are how do all the components in each cell are coordinated to ensure that the cell is functioning properly? What are the sets of biochemical reactions involved in a cell when it takes in nutrients and expel waste? It was improvements in experimental methods in biochemistry and biophysics from simple chemical tests to sophisticated analytical tools such as mass spectroscopy along with improvements of the optical microscope as well the invention of the electron microscope that made answering proximate questions which demanded knowing the inner workings of the cell possible.

The same scientific method that is based on proximate questions are present in developmental biology or the field of biology that studies the developmental processes or those processes that many life forms undergo from fertilization of two specialized cells or gametes into a embryo or developing mass of cells after fertilization into a fully functional organisms. How do all the cells that divide after division, which are identical to begin with, become specialized into different cells such as the set of cells that will become the muscles and so on?

All life shares the same genetic code and the study of genes, how they carry heritable information is the chief goal of genetics and what genetics has revealed is the fact that all of life, despite outward appearances, shares the same genetic code or if you like, the same program and the genetic code basically codes for amino acids or the building blocks of proteins and proteins have a wide variety of functions that are either universal in all life form or specific for some organisms depending on their needs. The proteins which are coded by the information stored and replicated in genes functions as catalysts, a.k.a enzymes which speed up biochemical reaction including how genes are replicated so genes carry the information for proteins, how they will function within the context of the cell, even for how heredity will be passed on to the next generation. The proximate questions for genetics are How do certain traits get passed on from the next generation? How do variations appear in a populations. How do the basic unit of heritable biological information, the genes, function in producing the sort of variation?

Genetics was originally started by investigations of pea plants by Mendel and he summarized how traits are passed on in 1865. Later the source of genetic variation focused from large scale observation of phenotypes in sexually reproducing organisms down to the cells and techniques in cell biology and biochemistry were used to answer the proximate question of the how do the units or factors of heredity form the variations, together with controlled breeding experiments of what are called model organisms or organisms only used for research purposes such as fruit flies, and this led to the fact that heredity is the result of genes organized in subcellular structures, the chromosomes.

As I have mentioned previously, reductionism is part of the scientific method and answering proximate questions requires the use of reductionism and this was the case for genetics and to understand how genes are responsible for heredity is to understand the chemical composition, which in 1944 and was explained in detail in my blog “The Breakthrough of 1944” , which for genes as composed of nucleic acids and if nucleic acids are responsible for heredity then how do the structure of nucleic acids, namely DNA relate to the function of heritable biological information? Through the use of biophysics such as x-ray crystallography along with known chemical and biological facts as revealed by Watson and Crick (1953), that DNA is a double helix and it is because of that particular structure that DNA can replicate and carry information to the next generation.

This is an example of how answering proximate questions can end up solving a problem which at first seem unrelated but shows that they do have something in common such as the fact that genes and nucleic acids, as originally inferred but not seen by Mendel and nucleic acids as isolated by Miescher are one and the same following the discovery of the double helix. These separate discoveries come together.

Living organism use energy to power themselves such as growth or finding mates and how organisms achieve this is answered by physiology and physiology’s proximate questions are how do the biochemical and genetic processes combine together to give an organism its functions? Physiology focuses on the activities of every organism from bacteria to humans by asking proximate questions that are universal that is what is it that metabolism of all organisms have in common and how do they work to ensure survival to specific proximate questions such as how does the oxygen intake vary depending on what a running rat is encountering?

You can see that most of the fields of biology are about answering proximate questions which varies depending on which field of biology is being considered. You now understand that biology is both descriptive (what?) and functional or proximate (how?) but sooner or later a “why” or ultimate questions will be answered and when answering ultimate questions. Only with natural selection as first proposed by Darwin (1859) together with the formation of the Modern Synthesis did ultimate questions became a legitimate scientific methodology and ultimate questions became part of the foundation of evolutionary biology, which I personally call the “grand unified theory” of biology in comparison to physics, a grand unified theory would explain the nature of forces and particles, evolution by natural selection explains all aspects of the biosphere as studied by all fields of biology by satisfactorily answering the ultimate questions that are asked in each field of biology whether it is in biochemistry, genetics, cell biology, and physiology for example and we will then see how evolution helped redefined biology when ultimate questions became a legitimate part of science.

                                            The “Why” Questions or Ultimate Questions

Why is there so many life forms , all different from one another? Why do some birds migrate while some do not? Why do a few species of insects such as bees produce a large amount of offspring that never reproduce? Why are past inhabitants different from those that are living and why did they become extinct?

The “why” questions or ultimate questions are about understanding the history of every species and through the natural history of every living species, each species had to adapt or perish in whatever change in environment there is present in short species evolve as revealed by Darwin, while challenging the western belief that each species was created independently by God and before Darwin when answering “why” questions was to fall back on the belief of a Creator.

Questions like these are actually as old as humanity itself and involve questions such as is the world the same way as it was before, did someone or something created this world? Before science reached the point of giving satisfactory answers to these questions, the only way to answer them was to rely on myths along with certain religious beliefs, and each culture had their own unique way of understanding the world. Eventually the kind of questions that are part of that human endeavor where a question was supported by observations and experiment, or science was beginning to be asked by the ancient Greeks during the rise of classical thinking that is characteristic and from Thales to Aristotle, questions were asked and answers were put forth through careful reasoning and some of these philosphers had evolutionary ideas that all life can be traced to a single ancestor and that the world was formed out of some primordial substance but much of what said was just pure speculation and not much progress was done in regards to understanding the natural history of the biological world, mainly because of Aristotle who believed that the whole cosmos is constant and fixed, mainly because of the influence of another philosopher Plato who belived that everything in the world is the result of “essences” or perfect, unchangeable things and in this world is a reflection of these “essences” or “types” and through Aristotle, the belief of an unchanging world became the basis of typological thinking and later during the Middle ages, when Christianity became a major religion as well a political force through the Pope to the Monarchs, a belief that God created the world and every living thing was the same as what came before became the dominate kind of thinking. Any alternative explanation was of course not tolerated.

Eventually with the coming of the Renaissance, the legitimacy of the Scriptures were challenged and following discoveries of species of animals and plants in continents such as the Americas and Asia together with new inventions such as the microscope which revealed a microscopic world of living things so small and so diverse and it was within this background of new ideas and discoveries that science slowly but surely became the endeavor to understand how the universe works and why it works and with questions that only science could answer while rejecting supernatural explanation, science could proceed answering descriptive and proximate questions but when it came to why questions especially in biology, some scientists still resorted to answering that God created this animal for this and this plant for that and so on. In some parts of Western Europe, especially in England, beginning with the work of Newton, a shift was focused on emphasizing the cause of whatever material activity was occurring and it was the focus of science to isolated and characterize the cause not just in physics but in biology as well. Also, In England as well as in continental Europe and up until the age of Enlightenment, a belief in a God was changed from a theistic belief or that God created everything in the universe and intervenes in every aspect of the living world including human life to a deistic belief or the belief that although God created the universe in the beginning He/She/It simply steps aside and let things be from then on.

As I have mentioned also, the mindset, in the western world was not just about various interpretation of Scriptures but it was also typological and as long as one believed in typology together with a literal belief in one’s religion, ultimate questions w(ere more theological than scientific and what was needed was a shift in thinking from a typological to what Mayr (1997) called “population thinking” and only one man had the genius to adopt population thinking and from then on, the foundation of evolutionary theory and that man was of course Charles Darwin.

Darwin , was not the only scientist to propose evolution as a theory. Previously because of the Enlightenment in which science and reason became the chief explanation instead of religion and became part of what was then the new intellectual climate of Europe and England, a few scholars considered the possibility of life form evolving but did not have a viable mechanism for one thing there was that belief in typology and Darwin of course was the first to appreciate population thinking ( of course Darwin himself never referred to it as such) and only with population thinking could a mechanism which is natural selection be a viable agent for evolution and that is what set Darwin apart from previous generations of scholars.

When The Origin of Species published in 1859, not every scientist accepted Darwin’s concept of natural selection and literal beliefs in Creation notwithstanding, it was because not every scientists as well as layperson at the time appreciated the power of population thinking (how could they in a society where a belief in typology was present) and although different evolutionary ideas were present before The Origin of Species and even after, there were still these alternative but testable evolutionary theories but in 1940’s after considerations of various evolutionary theories, it turned out the only correct theory of evolution was that based on natural selection and the reason why it succeeded where the others failed is the fact that this mechanism is based on population thinking while the other evolutionary theories were based on typology as well as a belief in a strive towards perfection. Only by considering populations as that affected by natural selection did natural selection as concept became natural selection became fact and thus evolution became a fact because of population thinking.

As Mayr (1997) pointed out ” Very few people realize that it was Darwin who was responsible for making “Why?” questions scientifically legitimate. And by asking these questions he brought all of natural history into science.” (pg. 116). This was only possible if population thinking was accepted instead of typology and not only do you have a history of evolution of a population but also a method for establishing inferences from an ancestor to what is observed day, that is events in the past influence what is in the present. From this, one can construct an evolutionary history but more importantly ultimate questions became part and parcel of every field of biology and here are examples for each field

  •   Biochemistry: Why do all organisms use the same kind of proteins for biochemical reactions? That is because around 3.8 billion years  the ancestor off all life form had a set of enzymes that could catalyze reactions and natural selection favored those cells with enzymes allowing them to survive to produce offspring and as life forms evolved into different habitats, the chemical reactions were inherited from the same ancestor and so were the enzymes, which are vital for chemical reactions
  • Genetics: Why is the genetic code universal? Since we know that the genetic code is what codes for proteins then once the genetic code appeared in the first life form, it was favored by natural selection along with the ability of the code to propagate itself because of the DNA molecule and so all life forms today inherited that genetic code ever since.
  • Cell biology: Why are cells are defined by a cell membrane? A cell membrane not only separates the inside of a cell from the outside world but also has transport proteins for  taking in certain substances and also for expelling as demanded by the cell’s metabolisms. A cell membrane with functional transport proteins is crucial for the cell’s long term survival and will be selected by natural selection.
  • Physiology: Why is the eye of animals so suited for vision? In the early history of the evolution of animals, the ability to sense light arose as a consequence of the evolution of multicellularity since an animal is composed of various kinds of cells that are specialized for a different function such as a vision. An eye can simple be a small organ with light sensitive neurons forming a retina that can distinguish light from dark is all that is needed to enable a simple invertebrate such as a clam to move towards food or to sense a hungry predator and take action. That would be favored by natural selection and as species of animals began to diversify so did their organs and through the animal kingdom in each lineages eyes in species of animals could either sense light or dark, or in some species such as insects , a compound eye resulting in a mosaic image, or a eye that could see nuances of shade, color, and movement. All of which would be favored for natural selection if it favored survival of the organism.
  • Zoology: Why do species of birds have different songs for mating? A species of animal such as birds, can be defined in terms of reproduction or what is called by Mayr(1997) the biological species concept (also due by Mayr who came up with this concept) and that is species are those that can interbreed with one another but not with other members of different species. There are biological mechanism that are shared by organisms in a species which kepts each population apart from other differing populations and in the case of birds, a song sung by a given bird species is recognized as a signal within the population that mating will occur in that population and this is part of the mechanism as allowed by natural selection not just in helping ensuring reproduction but natural selection is also the same mechanism that keeps species of birds apart and natural selection results in speciation or forming of new species while maintaining barriers between species.
  • Anatomy: Why are the same set of bones present in the arms of different mammals: Natural selection favors modifications of an underlying theme common to all mammals such as the bones in arms and because natural selection is involved in speciation, the reason for homology is that all species of mammals inherited that same plan from a distant mammalian ancestor.

And you can imagine ultimate questions for each subdiscipline for biology. These questions are not just legitimate but made possible by considering population thinking for without population thinking, ultimate questions becomes more of theology than of science.




In any field of biology, whatever question to be asked about the living world will either be a ultimate or proximate question but also a combination of the two. The combination of ultimate and proximate questions could never have been possible without the population thinking characteristic of Darwinian thinking.




Mayr (1997) This is Biology: The Science of the Living World: Harvard University Press, Cambridge, Mass

Comments are closed.