Course:EOSC311/2025/Evolution Through Geology

Intersection of Geology and Biology

Summary:

Geology is integral to understanding the Earth and the formation of our surroundings. There is huge impacts on human history through the shaping of our populations and world. Aiding in our knowledge and prediction of geological activities to better prepare for the consistent changes happening near us. Fossilization has allowed scientists to uncover the deep history of life on Earth, providing direct physical evidence of organisms that existed millions of years ago. Geological processes not only preserve these remains but also serve as a contextual framework for interpreting their significance in evolutionary terms. Sedimentary layers, mineralization conditions, and tectonic movements all contribute to how and where fossils are discovered, making geology indispensable to evolutionary inquiry. This project will explore several key components. Essentially, geology is the context and the setting of evolution and has the ability to share history with us today.

How Has Geology Shaped Our Understanding Evolution

Jurassic Park T-Rex, helpful in showcasing evolution and the geographic timescale to the public. Shows an imaginary but maybe possible idea of using fossils for a new purpose

Biology is the study of life. Part of knowing and understanding life on Earth is through understanding the history and patterns of life. The perception of evolution to the public is influenced by fact and fiction. The first major publication of evolutionary theory was from Charles Darwin in 1859, closely building on James Hutton's formation of ideas surrounding Earth's evolution and timescale. James Hutton is created with helping in the formation of modern geology. He realized the importance of erosion, uplift, and deposition in the shaping of the EarthCurrently about 60% of the American population believe in evolution, while a third completely reject it .

There is a tension between evolutionary theory and the church as some ideas have collided, with public acceptance growing since the 1990s to a majority. Geology holds a major pillar of the public understanding of evolution through fossils. Most people when they think of evolution think about fossils and the discovery of extinct species which hold similarities to species still on our planet. Something that has allowed the public to see the intersection of geology and biology is the Jurassic Park franchise. The popular movie showcases how important information of discovery and even in this example, reinvention, could be found in the past and used today. While the DNA capture in Jurassic Park is not entirely accurate, the ideas of fossils leading to possible cloning has become a reality. This has shaped how many of us perceive the importance of these two fields working together.

There is a growing interest in the field of how we can utilize fossils and other geological features to fill out the history of species and the land they lived on. On the topic of dinosaurs, geological features have led to the most public theory of mass extinction causing dinosaurs from the Mesozoic period to die off was due to a catastrophic event, a meteor. This hypothesis was published in 1980 by professors Luis and Walter Alvarez and was based off of evidence coinciding with geological features backing it. That includes shocked quartz in the area described where the meteor occurred, indicating a shock wave so powerful it rearranged rock. The general understanding of evolutionary theory seems to be building as the field of genetics increases the importance of evolution and the future of the planet.

Fossilization and Evolution

The Tiktaalik model at the Harvard Museum of Natural History. This fossil (on right) showed the transition of life in water to life on land. Helped biologists and paleontologists piece together the timeline of species on Earth.

Fossils are remnants of the past embedded and preserved in rock. There are two main categories, body fossils - parts of plant or animal, or trace fossils - footprints or other proof of life. Both of these categories lead to more information on the species in the fossil. Every part of our known or guessed history of life on this planet has come from fossils. One issue with fossils, is that the hardest parts of living species are typically preserved better this includes bones and teeth while soft parts often degrade. Original components are often replaced with minerals and showcasing an outline of living creature.

Fossils are typically formed when an animal or plant dies and is quickly buried by sediment including mud, volcanic ash, and sand. Fossils can form in a numerous amount ways including permineralization - dissolved minerals from ground water fill up cells in plants and animals minerals in this space can crystallize and become preserved, amber - tree resin can preserve certain aspects of living animals for millions of years, and soft tissues like hair, skin, etc. can be reserved in low oxygen and rapid burial which prevents scavenging and can happen in ice and volcanic ash. These processes are direct results of geological activity, following changes in weathering or larger scale including earthquakes and volcanic eruptions. Groundwater as described also plays a major role in fossilization through the mineral content from groundwater. Fossils are most likely sedimentary rock through sediments and living organisms forming together, and can contribute towards our understanding of evolution.

There is a worry that fossils found create a bias, not all living creatures become fossils additionally fossils only become a small part of picture as they tend to only show hard features of an animal leaving much to the imagination. Fossils have lead to huge advancements in our own understanding of human history, from a record of six million years ago of chimpanzee-like to hominid species showing a common ancestor between humans and chimpanzees which allows us to understand where we came from. Another incredible breakthrough leading to our better understanding of life on earth's history came from the Devonian period over 350 million years ago, which showed a living organism which held features of both aquatic and land organisms. This was then affirmed through DNA analysis of living species, biologists could then explain why hippos and whales share many complimentary DNA strands. There were many questions involving the shape and components in physiology today that geology has helped in answering. Evolutionary biologists have noted that embryos are highly conserved throughout many different species, showing human and other mammals as embryos highly resemble fish and other aquatic species. The ability to discover history hidden under our feet due to millions of years of geological processes has shaped our futures in understanding.

Plate tectonics on Earth, which are constantly moving and shaping how our world looks.

Tectonics and Speciation

Most Recent Common Ancestor of freshwater fish populations in New Zealand. Leading to understanding of tectonic influence on current fish populations of New Zealand.

The discovery of plate tectonics happened because of many, many scientists formulating different ideas to get to our knowledge today. This started as early as 1620 when Francis Bacon commented on instances on the Atlantic coastlines, much took case when Alfred Wegener proposed the theory of continental drift. Today, there is a wide belief that the contents of the earth are composed of different layers with the top layer (crust) shifting along the Earth due to components underneath causing different geothermal changes. Plate tectonics refers to the movement and interaction of large segments of the Earth's lithosphere, which float on the semi-fluid asthenosphere beneath. Plant interactions can cause new changes to the physical properties of the Earth. Volcanoes and earthquakes are both results of plate interactions, but boundaries of plates can also result in new mountain ranges, valleys, and rivers.

As continents move and landmasses split or collide, populations of organisms can become geographically isolated from one another, a key factor in the process of allopatric speciation. Speciation is the evolutionary process by which populations evolve to become distinct species, and geographic isolation often leads to genetic divergence as isolated populations adapt to different environments and accumulate genetic differences over time. For instance, when a landmass breaks apart due to tectonic activity, species that were once part of a single population may become separated by oceans or mountain ranges, preventing gene flow between the groups. Over thousands or millions of years, these isolated populations may evolve independently, developing unique adaptations and eventually becoming entirely separate species. In this way, plate tectonics not only shape the physical Earth but also drive biological evolution by influencing the distribution, isolation, and diversification of life on the planet.

The facts of speciation involve geographical separation and two different populations of one species. In the separation, natural mutations begin to occur in each population which continue to change the biological components of each populations leading to two distinct species from one common ancestor. Isolation and allopatric speciation can occur in many different ways, mostly due to tectonic plates shifting. One way in which there is a directional change from allopatric speciation happens when islands form, species on an island tend to have smaller resources and have less predation. Islands are hotspots of evolution, specifically in terms of radiative adaption. Adaptive radiation refers to how one species can rapidly change on an island to become many different to fill further niches. In New Zealand, there is a lot to study in terms of how geography and plate tectonics influence evolution of species. In this case study, they found distinct drainage catchments - an area of land where water collects when it rains often bounded by hills and filters into rivers and streams, which were the results of tectonic events, have sourced evolutionary differences between fresh water fish populations in New Zealand. They have said the evolution of these fresh water populations have been driven entirely by tectonic processes. This is just one singular case study which is able to attribute speciation solely due to tectonic activity which has been found due to a combination of geology and biology. Understanding the causes and relation of speciation and diversification is through the patterns of geological features.

Discovering Species and Phylogeny

Geology has played a pivotal role in deepening our understanding of phylogeny, the evolutionary history and relationships among species by providing a temporal and environmental context in which life has evolved. Through the study of rock layers, stratigraphy, fossils, and radiometric dating, geologists have helped biologists construct a detailed timeline of life on Earth, known as the geological time scale. Fossils embedded in sedimentary rock layers offer direct evidence of ancient life forms and their progression over millions of years, allowing scientists to trace lineages, identify transitional forms, and infer common ancestry among groups of organisms. For instance, the discovery of fossil intermediates like Tiktaalik, mentioned above, which exhibits features of both fish and early tetrapods has confirmed predicted links in the vertebrate lineage, leading to connections of aquatic life and land animals.

Example of a larger cladogram including dinosaurs

Geologic evidence also aids in understanding major extinction events and environmental shifts, such as volcanic eruptions, asteroid impacts, and continental drift, which have led to rapid evolutionary radiations and shifts in biodiversity. These geological phenomena often act as catalysts for speciation and extinction, reshaping the tree of life and influencing which lineages persisted or diverged. The intersection of biology and geology is particularly evident in disciplines like paleobiology and evolutionary biology, where molecular phylogenetics is used alongside fossil evidence to construct robust evolutionary trees. In essence, geology not only provides the physical framework and timing for biological evolution but also enables a multidisciplinary approach to studying the complex history of life, reinforcing the deep connection between Earth's dynamic processes and the unfolding narrative of biodiversity through time.

Through fossilization and studying the interrelationships of the past, we have come to further understand the interplay of how species today are related. Arthropods and their related species have become more well known, especially as their time on this planet has been much longer than mammals or other groups. We have been able to combine cladograms, which represent evolutionary relationships, with fossil records to create a bigger and more accurate picture. There are also issues in trying to fit both stratigraphic and phylogenic evidence, scorpions for example are considered to be the oldest arachnid in geological perspective but not in a phylogenic perspective.

Conclusion

The intersection of geology and biology has provided profound insights into the history and development of life on Earth, forming a powerful alliance that continues to reshape our understanding of evolution, speciation, and phylogeny. Through geological processes such as fossilization, plate tectonics, sedimentation, and radiometric dating, we gain the physical and temporal framework necessary to interpret the biological changes recorded in Earth’s strata. Fossils offer tangible connections between ancient and modern species, allowing scientists to reconstruct evolutionary pathways and infer relationships between organisms across vast stretches of time. As evidenced by iconic discoveries like Tiktaalik or the case of freshwater fish in New Zealand, geological activity directly influences the mechanisms of speciation by isolating populations and altering ecosystems. Additionally, popular culture like the Jurassic Park franchise has played a role in making these scientific concepts more accessible, demonstrating the power of storytelling in shaping public perception of science. While fiction often embellishes, it nevertheless highlights the importance of these fields working together. Today, the growing synergy between geological data and biological research, especially through tools like molecular phylogenetics and stratigraphic analysis, continues to unveil the deep connections that shape life on our planet. Ultimately, understanding Earth's dynamic systems both biological and geological not only enriches our knowledge of the past but equips us to face challenges in the future, from conservation to climate change, with a greater appreciation of the complex forces that drive life.

References

Barr, W. A., & Wood, B. (2024, August 22). Spatial bias in the fossil record affects understanding of human evolution. Nature News. https://www.nature.com/articles/s41559-024-02524-3

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