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From the dawn of civilization, biology has evolved gradually, beginning with philosophical views in early ages, passing through periods of medieval substantial milestones, and ending in the scientific revolution of the modern era. Thanks to this progression, we have reached the modern experimental science, which has expanded the horizons of human knowledge and reached unprecedented innovations in various fields.

Experimental science aims to understand and explain natural phenomena in a systematic and reliable approach, enabling the making of scientific predictions that can be tested experimentally. Experimental science is a systematic process that relies on observation, measuring, quantitative analyzing and experimentation to understand natural phenomena. It is characterized by the testing of scientific theories through repeatable experiments, allowing researchers to verify the results, which will either confirms a hypothesis turning it into a scientific fact, or disprove it.

Additionally, experimental science continuously evolves as new data emerges. Theories are modified or replaced when more objective, precise evidence is discovered. This ensures the reliability, neutrality, and accuracy of the results.

The Role of Theory in Experimental Science

Theories are fundamental to experimental science. At the most basic level, a scientific theory is defined as a systematic and organized explanation that accounts for a wide range of natural phenomena and facts. Additionally, it can make predictions that can be tested through experimentation. Furthermore, Theories can be updated and improved in light of new data, enabling the development of new, testable predictions. Through this continuous cycle of prediction, testing, and refinement, theories become more accurate and comprehensive. Therefore, there must be integration between theoretical and experimental work.

It is important to keep in mind that a theory’s scientific definition differs from how the general public typically perceives it. In everyday use, a theory means often a personal opinion, guess, or untested assumption. In contrast, a scientific theory begins with observation, followed by a hypothesis to explain a recurring natural phenomenon that lacks a clear scientific explanation. This hypothesis is then tested with evidence until it gains scientific acceptance. If a better explanation emerges, the theory is either modified or undergoes a paradigm shift.

The History of Evolutionary Theory

Evolutionary theory is a cornerstone of modern life sciences, supported by robust evidence from various scientific fields. The history of evolutionary theory spans centuries, tracing its roots back to philosophical ideas, progressing through the theories of Lamarck and Darwin, and culminating in the modern evolutionary synthesis and genomics. Each stage has contributed to our current understanding of evolution. Below is an overview of the history of evolutionary theory:

1. Ancient Philosophical Ideas

Some Greek philosophers discussed the idea that living organisms change over time. Anaximander (610–546 BCE) proposed primitive ideas about evolution, suggesting that life originated in water and that animals could be transformed from one kind to another. The theory of spontaneous generation, which states that life could emerge spontaneously from non-living matter, was later invalidated by experimental science and became a part of scientific history.

2. The Middle Ages

Predominant ideas during this time were largely influenced by religious interpretations, nevertheless some Muslim scholars, such as Al-Jahith and Ibn Khaldun, introduced concepts of change and adaptation. In his book The Book of Animals, Al-Jahith discussed the “struggle for existence,” noting that organisms compete for limited resources—a concept similar to what would later be known as natural selection. He also observed that animals adapt to their environments and that certain traits emerge as a result of this adaptation.

Similarly, Ibn Khaldun, though primarily focused on the evolution of human societies, contributed early insights into evolutionary thought. He noted that societies undergo stages of growth and decline, comparing them to the life cycles of organisms, and discussed how humans adapt to their geographical and climatic environments.

3. The Beginnings of Evolutionary Thought (1700–1800)

Georges-Louis Leclerc, Comte de Buffon, suggested that species might change over time due to environmental influences, stating, “Nature moves in slow steps but never retreats.” Erasmus Darwin, Charles Darwin’s grandfather, also wrote about the possibility of organisms evolving from a common ancestor, forming the groundwork for his grandson’s later theory.

4. The Foundation of Evolutionary Theory (1800–1900)

Lamarck’s (1744–1829): Lamarck proposed The Inheritance of Acquired Characteristics‘ and use and disuse. With the discovery of genetic inheritance which showed that acquired traits are not inherited , Lamarck’s idea was later refuted

Alfred Russel Wallace: Independently, Wallace developed a concept similar to natural selection, prompting Darwin to publish his theory.

Darwin’s Theory: The idea of natural selection was first proposed by Darwin. According to his view, organisms change as individuals become better adapted to their environment in order to survive and reproduce. This process is driven by natural variation in traits, rooted in genetic differences among individuals. Over time, advantageous traits accumulate in the population, leading to gradual changes in organisms over long periods and contributing to the diversity of life on Earth.

4. The 20th Century

Modern Evolutionary Synthesis (1942): Julian Huxley integrated Darwinism with Mendelian genetics, forming the modern evolutionary synthesis. This framework explains evolution and diversity through mutations and natural selection. Our understanding of how genetic changes drive evolution, significantly expanded by the discovery of DNA.

Punctuated Equilibrium (1972): Stephen Jay Gould and Niles Eldredge proposed this theory, suggesting that new species appear suddenly in the fossil record in small, geographically isolated populations, followed by long periods of stability. The new species then expands and competes with ancestral species, leading to their extinction. This theory fill in the gaps in the fossil record that cannot be explained by gradual change.

The 21st Century

Advances in genome sequencing technologies have allowed scientists to study evolution at the molecular level, deepening our understanding of evolutionary relationships among organisms.

Theories That Have Been Refuted or Modified

• Orthogenesis: Refuted.
• Saltationism: Modified.
• Gradualism: Modified.

Despite being refuted or modified, these theories have contributed to the improvement of scientific ideas and a better understanding of evolutionary mechanisms. Science progresses by building on previous knowledge and continuously correcting errors. From ancient philosophy to modern science, the evolution of theories across the ages highlights the progress of human thinking in gaining a deeper understanding of the world, emphasizing that science is our bridge to the future.

Recommended Reading

1. Darwin, C. (1859). On the Origin of Species by Means of Natural Selection. London: John Murray.
2. Darwin, E. (1794). Zoonomia, or the Laws of Organic Life. London: J. Johnson.
3. Green, S., Fagan, M. B., & Wylie, C. D. (2015). Evolutionary systems biology: Historical and philosophical perspectives on an emerging synthesis. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 324(7), 565–577. https://doi.org/10.1002/jez.b.22627
4. Bowler, Peter J. Evolution: The History of an Idea. 3rd ed., University of California Press, 1984.
5. Graham, Daniel W. “Presocratic Philosophy.” The Stanford Encyclopedia of Philosophy, edited by Edward N. Zalta and Uri Nodelman, Fall 2023 Edition, Stanford University, 2023, https://plato.stanford.edu/entries/presocratics/.
6. Ibn Khaldun. The Muqaddimah: An Introduction to History. Translated by Franz Rosenthal. Princeton: Princeton University Press, 1967.
7. Al Jazeera. (2023, February 22). هل يُسقط الإلحاد أهم قواعد منهج العلم؟[Does atheism overthrow the most important rules of the scientific method?]. Al Jazeera Net.
8. Dajani, R. Why I teach evolution to Muslim students. Nature520, 409 (2015). https://doi.org/10.1038/520409a
9. Lloyd, E. A. (2003). The modern evolutionary synthesis and its discontents. In Philosophy of Biology (pp. 217-232). Cambridge University Press. https://shorturl.at/74jdJ