Genetics And Evolution: Natural Selection

Rationale

“Humans have stopped evolving and are no longer subject to natural selection.”(O’Rourke, 2020)

Is an extremely broad claim with no evidence to support it, evolution is “the process by which new species or populations of living things develop from pre-existing forms through successive generations”(Gould, 2020)

Whereas “natural selection is the process of which a selective agent acts on a population and results in certain organisms having greater chances of survival.”(O’Rourke, 2020) Producing stronger second-generation offspring. Through these understandings it can be recognised that evolution and natural selection are two different processes.

Studies conducted by Dr. John Hawks reveals humans are actually still subject to Evolution in many ways, the most common through diet. Ira Flatow the host of the NPR podcast involving Hawks said, “ So are, really the diets that we choose, they're affecting our evolution, what we eat?” (Flatow, 2013)

This very statement sparked the motivation for investigation, are humans also part of natural selection even surrounding their diet? Depending on where an individual is placed geographically their diet can be different to someone living in a culturally and geographically diverse location. This is an example of natural selection being used to evolve humans in a modern world. During the transition from ape to humans “the evolutionary pressure of eating less fresh food subsequently favoured those better able to digest these naturally fermented foods.”(Haridy,2019)

This allowed the species who decreased time among the trees to develop “D-phenylacetic acid, a metabolite produced by lactic acid bacteria which appears in some foods as the fermentation process takes hold.”(Haridy,2019)

‘Has the consumption of fermented food affected genetic change within the human race?’

Background

The consumption of fermented food has created a HCA receptor which evolved over generations to process novel bacterial metabolites. The University of Leipzig discovered an immune function receptor (HCA), uniquely evolved in humans and apes, triggered by a metabolite from lactic acid bacteria (LAB) in fermented foods. This receptor likely mediates beneficial and anti-inflammatory effects of lactic acid bacteria in humans, cultures worldwide have their own traditional ways of consuming fermented food. The nutritional and cultural importance of these ancient foods continues through the present era. “It is hypothesised that roughly 10 million years ago humans evolved the ability to safely eat older fermenting food picked up off the ground.”(Haridy, 2019)

Multiple studies describe how fermented food has been fundamental in human evolution and wellbeing, roughly 1/3 of the human diet today is composed of fermented products, food is transformed in the gut gaining new properties and increasing its value to the organism. Initially humans millions of years ago were unable to digest lactic acid bacteria found in fermented food, and cultures less acquainted with fermented food these days are still evolving to better digest it. Figure 1 displays how properties from fermented food are absorbed. Fermented food has changed the human species through gut microbiota level, gastrointestinal microbiota live withing the digestive tracts of humans and protect against pathogens.

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Evidence

Consumption of fermented food is associated with differences in the gut microbiome and metabolome, studies were conducted by American Society For Microbiology (ASFM). Six thousand eight hundred and eleven individuals were studied for a period of four weeks, on their consumption of fermented food. The results showed significant differences between consumers and non-consumers, “the metabolome of fermented food consumers was enriched with conjugated linoleic acid (CLA), a putatively health-promoting molecule.”(Cristea,2019)

The process of fermentation occurred approximately 10,000 years ago in the Neolithic period, fermentation is the ancient practice of food preparation to be able to preserve it. Fermentation occurs either spontaneously from original ingredients, environment or is controlled by the addition of specific starters such as lactic acid bacteria (LAB). A survey of fermented products indicated that the count of viable lactic acid bacteria usually reaches at least 106 cells per ml.

Humans have changed in order to digest these foods through “d-phenylacetic acid, produced by LAB, which interacts with the human host through the activation of hydroxycarboxylic acid receptor 3 (HCA3) and is involved in the regulation of immune functions and energy homeostasis under changing metabolic and dietary conditions.”(Cristea, 2019)

Cultural and geographical diversity has also played a role in evolving the human race to better absorb these properties and survive in the wild. Western societies had access to cattle allowing them to create yoghurt and fermented meat products which is associated with better metabolic rates largely seen in the American population. Whereas countries who had access to seafood and naturally grown vegetables such as japan, and Korea have been associated with a lower prevalence of atopic dermatitis also known as eczema. This form of evolution is still occurring today as seen in the global obesity epidemic, in 2016 39% of adults worldwide were diagnosed as overweight, while in America 71.6% of people aged 20 and over are considered overweight. This is partially due to the lack of fermented food intake as the metabolic rate is slowing down. Japan is significantly lower with a national obesity rate of 3.7%, the difference in these two nations is for many reasons, the largest diet. Japanese portions are much smaller than Americans’ however they consume large amounts of miso, fermented vegetables and fish, the study conducted by ASFM supported this by showing the increased metabolic rates between nations and individuals depending on the fermented foods they consumed.

The gut microbiome is shaped and modified by microorganisms in the intestinal tract, “Its composition shows strong individual specificity and may play a crucial role in the human digestive system and metabolism.”(Chen, 2016)

A variety of factors influence the composition of the gut microbiome for example eating habits, living environment and antibiotic use. Therefore, various human races are characterized by diverse gut microbiome characteristics. NCIB conducted a study comparing the Asian, European and American diets and their gut microbiome composition. The study has proven that as a result of different cultures consuming diverse diets their gut microbiome composition and metabolism rates differ, these three races all live in varying environments which in turn affects the products and fermented products they consume. Figure 2 displays the diversity through fermented consumables across the globe. The separation in gut microbiome across cultures is an example of natural selection. The range of food and environment is and was a heavy influence throughout evolution as it allowed each culture to consume different fermented foods affecting the intestinal tracts and ability to absorb lactic acid bacteria (LAB). Natural selection and diet have both played critical roles in the development and absorption of fermented food throughout human evolution.

Evaluation

NCIB is the National Centre for Biotechnology Information USA, this source provided information on how gut microbiome levels differ between races. They are part of the United States National Library of Medicine, a branch of the national institution of health. The source is highly reliable as it is run and monitored by the government, and not partaking in debates making it unbiased. All articles are heavily science based, as well as being written by multiple academics. The investigation was published in 2016 allowing for the research to still be viable and not out-dated, this was a trusted and valuable source for the research and evidence.

The research investigation conducted by the American Society for Microbiology provided information into how consumers and nonconsumers of fermented food gut microbiomes and health differed. This source was published on the twenty-eighth of April year two thousand and twenty, meaning it has been produced and published recently. Eliminating the chance of providing outdated data, there are also numerous qualified authors working together to create information which is highly reliable. The American Society for Microbiology is a professional organisation for researchers and scientists who study viruses, bacteria, fungi, algae and protozoa. Overall this is a highly reliable source, essential for the investigation of this task.

New Atlas is a magazine or subscription paper on science, technology, lifestyle and transport, Rich Haridy wrote the article inspiring the research question. The articles was focused on how humans have benefitted and evolved from eating fermented food. The website was professionally structured, however lacked in scientific evidence and knowledge in comparison to the other sources. It was written in 2019 allowing for the information to be relevant and not outdated. The fact that it lacked scientific information helped the researcher to locate more studies on this topic, broadening overall knowledge. The company New Atlas has been rated highly credible, however this one page needed supporting research for it to be completely trustworthy.

Conclusion

With evidence shown above it can be witnessed that the consumption of fermented food has created genetic differences among the human races. Humans in the Neolithic period evolved the ability to digest foods with lactic acid bacteria, allowing them to eat fruits from the ground and spend less time in the trees. Today these differences are evident among races, gut microbiome levels differ between Asian, European and American species. The levels of gut metabolome is affected by diet, therefore races in diverse locations have access to diverses foods altering their ability to absorb lactic acid bacteria. This is how natural selection has played a role is affecting the evolution and consumption of fermented foods throughout species. Fermented food has certainly been a factor in the evolution of the human race throughout ancient and recent times.