The Devolution of Evolution
Why evolution and biosystematics courses must be included in all biomedical curricula.
Nearly 40 years ago Theodosius Dobzhansky wrote: “Nothing in biology makes sense except in the light of evolution.” How is it, then, that so few newly minted PhDs in the biological sciences have taken any formal graduate school courses in evolution or biodiversity? This fosters a knowledge gap that can become difficult to fill by “osmosis” later in a scientific career. Consider the two to five years of intense postdoctoral work, followed by the even more challenging process of earning tenure. Success requires complete dedication to a specialized field of knowledge for professors who then act as advisors for the next generation of scientists, judge hundreds of submitted papers and dozens of grants, and chart new research directions.
To some extent the problem appears to be hereditary: a generation of biologists without an adequate background in evolution gave rise to a second generation of biologists who came of age during the molecular biology boom of the 1980s and 1990s. These trends could now repeat with a third generation working in the current genomic era that began early in the 21st century.
Indeed, it appears that evolutionary biology and biosystematics courses, which deal with the most fundamental concepts in biology, have quietly lost their place of eminence within the biomedical curriculum—“outcompeted” by escalating specialization and the increasingly technical nature of many biological sciences. By failing to require or even offer such essential courses to graduate students, do we lose some strategic advantage as well as a long-term perspective? I think we do by sacrificing a deeper understanding of the fundamental laws of biology. Evolutionary theory, speciation, principles of biological classification, and biodiversity must be part of the required curricula not only for biologists but for medical students as well.
Students of engineering must learn the fundamentals of mathematics and physics. A PhD chemist cannot bypass learning the periodic table and its elements. In contrast, ask a young or even a senior biologist with an active research program to name 15 to 20 animal phyla. Most could correctly name 5 to 10 of the 35 currently known. I cannot image a chemist who is unable to refer to or actually recognize most of the chemical elements. It is unthinkable for the chemical curriculum to allow a student of organic chemistry to electively study the properties of carbon, hydrogen, oxygen, nitrogen, sulfur, and phosphorus, or to ignore iron or molybdenum. Why have we accepted ignorance of evolutionary theory and knowledge of biodiversity in classrooms? What effectively distinguishes a biologist from a nonbiologist is the appreciation and understanding of the vast biodiversity of life. Yes, elective courses are essential for creative thinking; they reflect the dynamic nature of modern education, but only if the fundamental biological concepts such as natural selection are secured in the curriculum.
Evolutionary principles integrate all the concepts underlying cell biology, genomics, and medicine. It is by mastering the “how” underlying such principles that we are trained to ask “why?” Why do we observe certain types of cellular or systemic organizations instead of others? These “why” questions target the causes, and new experimental designs reveal and explain the origins of biological complexity.
Why, for example, are individual neurons so different from each other? One possible answer is the functional demands within a given neural circuit and behavior. Another is that each distinct neuronal population has a different evolutionary history, and, as a result, neurons carry the heavy molecular burdens of their complex evolutionary past. Such distinctive ancestries might either limit or facilitate future evolutionary opportunities to adapt to changeable environments. In other words, past evolutionary history might provide constraints for the emergence of novel behaviors or resistance to stress, disease, or injury.
Many, if not most, breakthroughs in biology and medicine have come by studying experimental models representing the entire spectrum of the diversity of life: from bacteria to yeasts, from infusorians to algae, from hydra to squid and sea slugs. The doctor’s pragmatic interest in healing and repair and the synthetic biologist’s ambitious dream to build a new life-form require a deep understanding of life’s evolutionary history. This knowledge, when integrated with genome-wide understanding of physiological functions, offers dreams of building a new cell, a new neuron, a new brain, and even a new mind. It hints that there may be more than one way to achieve a particular goal in bioengineering or regenerative medicine, given the modular organization of biological systems and processes. Remarkable examples of parallel evolution exist within all animal phyla.
Sparks of the deep evolutionary past are also present in every cell of the human body. And our battle with diseases and infectious agents continues to drive the ongoing evolutionary process. Indeed, next-generation sequencing technologies are now so powerful that the epigenomes of all major cell lineages and the genomes of representatives of all 35 animal phyla and their 100 extant classes must and will be sequenced within the next few years. With the trend toward sequencing that costs less than $1000 per genome, one can foresee the time when all known creatures on the tree of life will be sequenced and analyzed, opening new doors for research on our understanding of adaptive modifications and the novelties that have arisen over 3.5 billion years of biological evolution. Such a genomic blueprint of the grand diversity of life would truly be a universe-scale achievement for humankind, securing our past, present, and future.
We continue to evolve together with our pets, parasites, symbionts, food, land, and ocean ecosystems. As Peter Medawar eloquently put it, “The alternative to thinking in evolutionary terms is not to think at all.” The sooner evolution and biodiversity are inherent and required parts of every biomedical student’s curriculum, the greater progress we can expect from a new generation of scientists in the clinic and the laboratory. Whether we like it or not, biology simply means evolution.
Leonid Moroz is a professor of neuroscience, chemistry, and biology at the University of Florida College of Medicine in Gainesville and the Whitney Laboratory for Marine Bioscience, where he studies the genomic bases of memory and the origin of neurons and nervous systems.