The Spirit Of Survival - Part I

                   Preface

People who appreciate aged distillates, regardless of the spirits category, rarely stop to think about the evolutionary paths taken by nature in order to make their beverages possible.  We rely on yeast’s “chemical warfare” prowess to produce ethanol, which we later infuse with tannins that were originally evolved by plants as defense against predation.  And while yeast evolved the ability to produce alcohol as a way to fend off bacteria and fungi, it is human’s appreciation for ethanol that ultimately has ensured the large-scale propagation and perpetuity of yeast, begging the question of “who serves who?”

                                            The Water of Life

It is widely-accepted that life originated in water, in the form of simple microorganisms similar to modern-day algae.  As the geography of the early planet changed and land surfaces became exposed, these early life forms were able to experiment with mutations and survival strategies aimed at exploiting the living conditions on dry land.  Plants became homoiohydric, that is, they evolved vascular systems, designed to transfer water from the root zone, to the opposite extremes above ground(1).

One of the earliest evolutionary adaptations was photosynthesis, or the ability to use the sun’s light energy to produce food from carbon dioxide and water molecules.  Photosynthesis requires for plants to absorb CO2 from the atmosphere. This ability, however, comes at a price, since the tissues available for CO2 to enter the plants also allow stored water to evaporate.  To mitigate the evaporative water loss, plants evolved specialized cells that increased the impermeability of their outer membranes.  But this ability to synthesize food was not a survival guarantee: plants also had to evolve ways to store the newly-created food in order to cope with changing environmental conditions.

                                  Saving For A (Not) Rainy Day

For plants, being able to store food resulted in increased growth opportunities, but growing required specialized structures able to support the additional weight while functioning as a vascular system for nutrient transportation.  As plants got bigger, so did the competition for sun, but the rewards were worth it: taller plants could gather more sunlight (for photosynthesis) and the wind could spread their seeds farther away.  The needed structural integrity came from the development of specialized xylem cells, which were more conductive (providing vascular efficiency) and more resistance to collapse.  Lignified walls then led to Arborescence (plants growing in tree-like shapes), which involved secondary growth (vascular cambium).  

The first plants to develop secondary growth and a woody habit are thought to have been ferns, and as early as the Middle Devonian period, the Wattieza species had already reached heights of 26 feet (8 meters) and a tree-like habit(2). 

Early trees were free-sporing specimens, which later evolved into today’s main tree groups, known as gymnosperms, or seed-producing trees, a group that includes all coniferous and nut/fruit-producing trees, including our beloved white oak, used in the manufacture of most of today’s barrels.

The evolutionary origin of white oaks was shrouded in mystery until a few years ago.  There are approximately 125 species in the Americas and around 25 more in Eurasia, but little was known about their origin.  According to research conducted by Andrew Hipp of The Morton Arboretum and Paul Manos and John McVay of Duke University(3), Eurasian white oaks arose from a North American ancestor that migrated to Europe, perhaps by way of the North Atlantic land bridge.  The researchers used genomic data, fossil records and leading edge analytical methods to answer the question regarding the white oak’s mysterious origin.

Plant life has evolved from simple single-cell organisms to complex flowering/seeding structures, some towering 100+ feet (30+ meters) from the ground.  As they adapted to their environment, plants evolved offensive, as well as, defensive survival strategies.  But plant predators also evolved their share of strategies, all aimed at perpetuating their forms of life.  Today we are able to see specimens showcasing winning combinations of such stratagems, living testaments to nature’s adaptability and efficiency.

                                      Bacteria, Virus and Fungi

According to Encyclopedia Britannica, “genomic surveys show that plant genomes lack gene sequences that are crucial in animal development, animal genomes lack gene sequences that are crucial in plant development, and fungal genomes have none of the sequences that are important in controlling multicellular development in animals or plants.”  Such fundamental genetic differences imply that animals, plants and fungi are indeed very different organisms today, but molecular analyses indicate that they diverged from a single ancestor almost one billion years ago.

As plants evolved into more and more complex forms, so did the organisms that relied on those same plants as their source of food or as their hosts for reproduction.

Bacteria

Fossil evidence indicates that the first life forms were bacteria, more than likely in the form of extremophiles that can tolerate extremes of temperature, salt concentration, radiation, pH and other environmental factors.  Such organisms are part of the division of life known as the Archae, specifically the archaebacteria.  One type of bacteria that is definitely known to have been among the first to appear on earth is the cyanobacteria.  Fossils of cyanobacteria have been uncovered that date back almost 4 billion years. These bacteria are suited to the low oxygen levels that were present in the planet’s atmosphere at that time. 

The cyanobacteria produced oxygen as a waste gas of their metabolic processes and so helped to create an atmosphere containing a greater amount of oxygen. Other, oxygen-requiring bacteria could then develop, along with additional life forms.  There are other interesting bacteria that evolved abilities to ferment glucose into lactic or acetic acid; perhaps we will explore these in a future article.

Viruses

In contrast to bacteria, scientists debate if viruses are even alive, since they are not capable of their own reproduction. Instead, they require the presence of a host in which they can introduce their genetic material. Through the formation of products encoded by the viral genetic material and by the use of aspects of the host’s replication machinery, viruses are able to direct the manufacture and assembly of components to produce new viruses.

Scientists are in general agreement that the first virus was a fragment of DNA or ribonucleic acid (RNA) from an eventual prokaryotic or eukaryotic host. The genetic fragment somehow was incorporated into a eukaryotic and became replicated along with the host’s genetic material. Different viruses developed over time, each designed to take advantage of the new bacteria and eukaryotic cells that were evolving.  In other words, as bacteria increased in diversity and in the complexity, new viruses evolved to be able to utilize the bacteria as a replication factory. Similarly, as more complex eukaryotic life forms appeared, such as plants, insects, birds, and mammals, viruses evolved that were capable of utilizing them as well.

Fungi and Yeast

Fungi are organisms that are neither plants nor animals, but which exhibit some traits of both.  Fungi cannot produce their own food (they do not have chlorophyll) so they rely on absorbing nutrients from usually dead plants and animals.  Yeast are a species of single-celled fungi that achieved notoriety for their ability to ferment sugars, but more about this later on.

                             The Best Defense Is A Good Offense

As you have seen, competition among plant species led to adaptation and resulted in different strategies for survival: some growing taller, others growing waxy coatings, etc.  Many plants and trees, including white oaks, developed bitter-tasting tannins, which they use to defend against insect herbivores by deterrence and/or toxicity.  The production of tannins as a strategy for survival has been so successful, that they are the most abundant secondary metabolites made by plants(4).

Yeast also evolved chemical warfare mechanisms to keep microbes and bacteria from consuming all the nutrients around them.  Scientists believe that fermentation was the yeast’s survival strategy, aimed at inoculating their surroundings by killing competing bacteria and fungi through contact with ethanol (yeast’s tolerance to ethanol evolved alongside its ability to produce it).

Unsurprisingly, nature continues to evolve. Some changes go unnoticed while others have almost immediate consequences.  Perhaps the most graphic of these evolutions happens in the world of bacteria and viruses, where some bacteria develop resistance to antibiotics (by producing enzymes that neutralize the antibiotics) and where strains of the flu virus mutate into new forms, sometimes from one year to the next.

The Human Factor

So much has already been published about the history of fermentation and distillation that I won’t bother repeating it.  Suffice it to say that humans LOVE fermented and distilled beverages.  But something interesting happened as early craftsmen looked for ways to store and transport those beverages in oak barrels: the tannins from the wood were extracted into the alcohol and, after sufficient resting time, they became softer and mellower! 

The same tannins that plants evolved as deterrents against predators turned out to be appealing to our palates, but only after being oxidized (reduced, if you are a chemist) during aging inside the barrels.

Humans are the only animals known to willingly consume foods or substances that cause them irritation, discomfort, even pain.  Proposed theories explaining “why?” range from thrill-seeking behaviors to an evolutionary adaptation for seeking foods that reduce pathogens.  One of the explanations is known as the Drunken Monkey Theory, and it suggest that our attraction to alcohol evolved from a powerful sensory bias associating it with nutritional reward: our ancestral primates evolved as fruit eaters in tropical rainforests, environments where yeasts abound and where fermentation is fast because of the warm and moist climate. While the ripe fruit may be hard to find visually, the smell of fermenting fruit can lead us more efficiently to it.  Alcohol also stimulates feeding, just as it does in modern humans via the aperitif effect. 

                                    Conclusion

Humanity today relies on yeast to produce industrial and food-grade ethanol at an unprecedented scale.  This dependence has ensured our protection and perpetuation of the yeast species needed for the fermentation.  

Our reliance on white oak trees for barrels has also led to reforesting activities aimed at preserving these special trees long into the future.  

As evolutionary survival strategies go, fending off microbes and insects, while stimulating humans into becoming their beneficiaries and protectors is definitely a winning combination!

                                    References:

  1. Sperry, J. S. (2003). “Evolution of Water Transport and Xylem Structure”. International Journal of Plant Sciences.Stein,
  2. W.E.; Mannolini, F.; Hernick, L.V.; Landing, E.; Berry, C.M. (2007). “Giant cladoxylopsid trees resolve the enigma of the Earth’s earliest forest stumps at Gilboa”. Nature. 446 (7138): 904–7.
  3. John D. McVay, Andrew L. Hipp, Paul S. Manos. A genetic legacy of introgression confounds phylogeny and biogeography in oaks. Proceedings of the Royal Society B: Biological Sciences, 2017.
  4. Barbehenn RV, Peter Constabel C.  “Tannins in plant-herbivore interactions”. Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan.