From bacteria to altruistic behavior, evolution is one of my favorite topics of all time. With the long history of how the theory of evolution was developed, it’s no doubt a fascinating topic with a huge influence on our world today. In fact, recently, it has been announced that the COVID-19 virus, formally called SARS-CoV-2, has been found to have multiple mutations that increases transmission and lethality, and this is all due to evolution. However, evolution has had its fair share of controversies, particularly regarding religion. But even today, the theory of evolution itself has been evolving with new discoveries and applications.
The beginning of the theory of evolution
Philosophers have long pondered about how humans came to be, as in 500s B.C.E, Anaximander of Miletus, a Greek philosopher, speculated that humans must have descended from an animal that could survive alone immediately after being born after he noticed that human babies are born helpless. He came to the conclusion that all life must have begun from the sea, as fish are able to survive immediately after being born.
While this was yet to become a theory, his idea was later proven when scientists began testing and finding evidence for the idea of evolution. In the 19th century, Charles Darwin had been working on his theory of evolution for nearly 20 years when a British naturalist named Alfred Russel Wallace reached out to him, as Wallace had independently came to the realization that species evolved when the fittest individuals in the environment survived and reproduced, increasing the frequency of a trait.
While the men presented their ideas jointly in a meeting of the Linnean Society, Darwin was more established in the scientific community and more commonly remembered as the discoverer of the theory, although Wallace came to similar conclusions independently. However, Wallace did not express any resentment over this, in fact, he was one of Darwin’s biggest supporters, and his role in this discovery allowed him to rise in the ranks of the scientific community.
In 1859, Charles Darwin published his book, “On the Origin of Species,” which described the theory of evolution by natural selection. In his book, he stated that one, a diverse group of animals evolved from a few common ancestors, and two, this happens due to evolution by natural selection. In this theory, it states that organisms with traits that are favored in their environments survive and reproduce to pass down their genes better than organisms without the trait, and this subsequently causes the trait to become more frequent in the population.
This was a groundbreaking piece of scientific literature, as there had been previous theories for natural selection, including John Baptiste de Lamarck’s Theory of Lamarckism that stated that organisms acquired and passed down traits throughout their lifetime through the increased use of that particular organ or part, and Charles Darwin’s grandfather, Erasmus Darwin’s theory that inspired Charles Darwin’s theory of evolution, but none of which could accurately explain the theory of evolution.
However, this theory was highly controversial
Darwin’s theory heavily contradicted biblical theories about the creation of humans, in particular, with Abrahamic religions, which include Judaism, Christianity, and Islam, which states that God created the world, including all life in the form they exist in today.
The reason for the religious controversy is because many religions believe that God created all life in the form we know today, with species remaining unchanging. This has led to arguments about how evolution is absolutely incompatible with religion, meaning that either religion or evolution must be denounced.
While some parts of the theory do directly contradict with religious beliefs, the organization Understanding Evolution illustrates this as, “Science deals with natural causes for natural phenomena, while religion deals with beliefs that are beyond the natural world.”
However, this controversy has made its impact on education, as in 1925, John Thomas Scopes, a high school teacher in Tennessee, was famously put on trial for teaching evolution and violating the Butler Act, which banned evolution from being taught in Tennessee schools. Even today, around 15% of teachers fail to emphasize the wide scientific consensus on evolution. Nevertheless, Darwin’s theory of evolution by natural selection was built entirely on scientific observations, including evidence he gathered during his surveying expedition aboard the HMS Beagle in the 1830s.
Many religious groups accept evolution as dealing with the natural world, while religion deals with the supernatural and spiritual world. In fact, many religious organizations have released statements that explicitly state that there should be no conflict between evolution and religion, while a survey on scientists at top research universities found that more than 75% believed that religions convey important truths.
“One of the greatest tragedies of our time, is this impression that has been created that science and religion have to be at war”Francis Collins, former director of the National Human Genome Research Institute and a Christian
Today, the theory of evolution has not stopped evolving
In 2008, Neil Shubin, a paleontologist at the University of Chicago, published his book called “Your Inner Fish: A Journey into the 3.5-Billion-Year-History of the Human Body.” Neil Shubin made a groundbreaking discovery when he discovered the tiktaalik roseae, which is described as “the link between fish and land animals.” The tiktaalik has scales and fin webbing like a fish, but a flat head and eyes and a neck like a land animal.
The importance of this discovery is because it provides a crucial piece of evidence that supports evolution, as Anaximander of Miletus predicted, if land animals really evolved from fish, then there must be a fish with primitive limbs that allowed them to move on land. With the discovery of tiktaalik, this provided evidence for evolution of fish into land animals, and as Darwin’s theory of evolution predicted, a diverse group of land animals evolved from a single common ancestor, the tiktaalik.
“It has a neck… No fish has a neck. And you know what? When you look inside the fin, and you take off those fin rays, you find an upper arm bone, a forearm, and a wrist.”Neil Shubin, a paleontologist at the University of Chicago
In addition, evolution was used to explain human behavior, as in 1975, American biologist Edward Osborne Wilson published the book, “Sociobiology: The New Synthesis” that argued that natural selection could explain human behavior and psychological patterns.
This was a very controversial theory, since some stated this theory as a form of genetic determinism, which is a belief that states that human behavior is directly controlled by their genes. However, because of natural selection, biological altruism is favored in communities, as it is crucial for a community to work together in order to improve the survival of the species as a whole.
One theory that I find particularly intriguing is Gerald Crabtree’s theory that humans are becoming less intelligent due to an accumulation of deleterious mutations. In an article published in Trends in Genetics, Crabtree, a professor of developmental biology at Stanford University, states that an average citizen from 1000 B.C.E Greece would be one of the most intelligent minds in our society today, and this is due to the lack of selective pressures in today’s world that allows deleterious mutations to accumulate, and with each mutation, this lowers our intellectual and emotional stability.
Because human intelligence requires 2,000 to 5,000 genes to be functioning optimally, this requires a large selective pressure to maintain. However, while Homo Sapiens as hunter-gather species relied heavily on wits to survive and thus evolved to have a larger brain, intelligence hasn’t been quite so crucial in terms of our survival since humans became a dominant species. Crabtree illustrates this when he states, “A hunter-gatherer who did not correctly conceive a solution to providing food or shelter probably died, along with his or her progeny, whereas a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus and be a more attractive mate.”
However, his paper was met with controversy as many criticized his lack of data in his paper and stated that his hypothesis could never be tested, despite the facts and circumstantial evidence it presented.
“A hunter-gatherer who did not correctly conceive a solution to providing food or shelter probably died, along with his or her progeny, whereas a modern Wall Street executive that made a similar conceptual mistake would receive a substantial bonus and be a more attractive mate.”Gerald Crabtree, a professor of developmental biology at Stanford University
There are still many misconceptions about evolution
However, while this theory is often summarized as “survival of the fittest,” it’s important to distinguish between physical fitness and evolutionary fitness. Physical fitness does not necessarily mean evolutionary fitness, and in fact, evolutionary fitness only refers to the traits that make an organism most fit to survive and pass down its genes in its current environment. In an environment that favors intelligent individuals over physical fitness, the traits for intelligence will be more likely to be passed down. So, fit refers to fit for the environment rather than physical fitness.
However, when an environment changes quickly, such as due to climate change, the organisms that were previously fit for the environment would be at a disadvantage. One notable real life example of evolution were the peppered moths in the United Kingdom. In the 1800s, there were two types of peppered moths: one with white wings and another rare type with black wings.
However, during that time, the United Kingdom experienced an industrial revolution that caused a dark smoke in the atmosphere. By the 1900s, nearly 98% of peppered moths had black wings, even though this variant had been rare just a couple years ago. Because of the dark smoke caused by the industrial revolution, black moths had a selective advantage over white moths, which caused them to be more prevalent in the population. But when the government began passing environmental regulations, the white moths became more common again as predators were able to spot the black moths.
In addition, evolution is not a single event, it happens all the time. One common misconception about evolution is the idea that humans suddenly evolved from apes in one event, but human evolution actually occurred through thousands of years, starting from the evolution into land animals.
However, there are many incidences of evolution occurring quickly. For example, antibiotic resistance occurs due to natural selection, and bacteria can gain nearly 300 mutations within 10 hours. With this rate of mutations, bacteria can quickly acquire resistance to antibiotics, much faster than the rate of human evolution. In fact, the first antibiotic was discovered nearly a century ago, but today, more than 70% of bacteria that cause infections have acquired resistance to at least one antibiotic most commonly used to treat the infection, and this is all due to natural selection and evolution.
Similarly, evolution doesn’t occur on an individual scale, it occurs on a population scale. Variation in the population occurs due to mutations that cause random gene variants called alleles, and alleles that are better suited for the environment will be favored and selected for through natural selection, making it more common in the population. Changes in an individual organism are either developmental, which include changes as an animal grows, or caused by the environment, such as disease or climate change, and none of which involve changes in the genome.
Yet, you may be asking, why aren’t humans evolving today? The truth is, while humans are still evolving and adapting to our environment, because of technology, there has been less of a selective pressure to continue evolving. Because we are now able to treat many diseases, such as juvenile diabetes, there is less of a selective pressure against the genes that carry those diseases.
However, humans are still evolving through “microevolution.” In fact, in a study published in the Journey of Anatomy, scientists found that babies born today are more likely to form more arteries and have no wisdom teeth to adapt to our environment and lifestyle. But while selective pressures have decreased, sexual selection is another type of selective pressure that plays a role in evolution. Today, humans have more freedom in choosing their own mate as many cultures are moving away from arranged marriages, and this means that sexual selection will play an important role in the evolution of humans.
Evolution also plays a role in disease trends
This is because first, the pathogens infect and colonize the human body for nutrition, and also replicate through the host and spread to other hosts.
While it may seem like the deadliest pathogen is considered the most successful, that’s actually not the case. The deadlier the pathogen, the more likely it is that the host won’t be able to interact with others and allow the pathogen to spread, and the spread of the pathogen is important for the success of a pathogen. After all, if you’re extremely sick, you’re likely to stay home, but if you feel well enough to go outside, then you’ll be able to spread the disease. That’s also why flu and cold medications may do damage, since if you feel too sick to go to school or work but suppress the symptoms using medication, you may be spreading a more virulent form of the virus to your friends and coworkers.
However, while we know that there are beneficial bacteria in our bodies as well as harmful pathogens, what causes pathogens to turn pathogenic if it’s not particularly beneficial to kill your host?
One of my favorite scientific papers discusses this. This paper, titled, “What makes pathogens pathogenic,” states that, “…the balance between host and microbe can be tipped from commensalism to pathogenicity… It is therefore likely that many pathogens did not initially evolve as pathogens, but simply take on this role as a result of a lack of ability of the host to maintain homeostasis.”
In other terms, this means that if the microbe is unable to survive as a beneficial germ, then they may turn into pathogens in order to survive, and the pathogenicity can depend on the amount of bacteria or viruses in the body. However, the other reason for why we associate pathogens with disease is actually because of our own immune response. In fact, many symptoms of disease are the effect of our own immune system, for example, fevers are caused by the immune system in order to kill off the pathogens by increasing temperature, while swelling and pus is the product when the immune system kills off the pathogens.
Recently, scientists have found many mutations in the COVID-19 virus
But because deadliness doesn’t always equate to success as a pathogen, some pathogens evolve to become a less virulent form in order to survive. Recently, a major question with the COVID-19 pandemic is whether or not COVID-19 will evolve to become like the seasonal flu, or become worse.
In the summer of 2020, a researcher in Texas found that the COVID-19 virus had a mutation in the spike protein that allowed for better transmission, and because this mutation gave the virus a fitness advantage, it became the dominant strain. Since then, scientists have discovered multiple mutations that can increase transmission, increase lethality, and increased ability to evade our immune system.
However, scientists analyzed the data from cases, death rates, recoveries, testing rates and hospitalizations and found that there was a strong association with temperature and latitude, which means that COVID-19 may be seasonal like the flu. This has led to predictions that COVID-19 may be more similar to the seasonal flu than any other virus, and in this case, winter cold and flu season may include COVID-19 as well. In fact, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, stated, “I doubt we are going to eradicate this.”
In total, because of the virus’ incredible ability to mutate and evade vaccines, COVID-19 may evolve to become an endemic disease, although likely in a less severe form. This has already been other cases of this happening with coronaviruses, as other human coronaviruses including the common cold have evolved to become endemic, and COVID-19 might just be the fifth human coronavirus. While lifelong immunity to COVID-19 is unlikely, a second infection is likely to be less serious than the first.
While evolution may seem like an old concept that you (hopefully) had to learn in high school, it’s actually a fascinating theory that has been strongly supported by many pieces of evidence, and even today, the theory itself hasn’t stopped evolving. Scientists are continuously figuring out new ways to explain the natural world using the theory of evolution, as well as finding new evidence to support the theory.
In particular, evolution is important in regards to what COVID-19 will be like in the future, and because of evolution, scientists are beginning to believe that COVID-19 will become a seasonal virus, like the common cold or the flu. Despite the controversies of evolution, many religious groups agree that the theory of evolution only deals with phenomena in the natural world, while religion deals with the supernatural and spiritual world. So while evolution may seem long forgotten in your textbook, evolution actually has a huge influence on our world today, from bacterial infections to human behavior.
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