Target Health Blog

Evolutionary Biology: From Darwin to Dawkins

November 26, 2018

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Quiz
Source:

Ernst Haeckel's Tree of Life (1879)
Graphic credit: By Ernst Haeckel - First version from en.wikipedia; description page was here. Later versions derived from this scan, from the American Philosophical Society Museum., Public Domain,
https://commons.wikimedia.org/w/index.php?curid=2731459

Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms, development and evolution. Despite the complexity of the science, there are certain unifying concepts that consolidate it into a single, coherent field. Biology recognizes the cell as the basic unit of 1) ___, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species. Living organisms are open systems that survive by transforming energy and decreasing their local entropy to maintain a stable and vital condition defined as 2) ___.

Sub-disciplines of biology are defined by the research methods employed and the kind of system studied: theoretical biology uses mathematical methods to formulate quantitative models while experimental biology performs empirical experiments to test the validity of proposed theories and understand the mechanisms underlying life and how it appeared and evolved from non-living matter about 4 billion years ago through a gradual increase in the complexity of the system. Evolutionary biology is the subfield of 3) ___ that studies the evolutionary processes that produced the diversity of life on Earth, starting from a single common ancestor. These processes include natural selection, common descent, and speciation.

The discipline emerged through what Julian Huxley called the modern synthesis (of the 1930's) of understanding from several previously unrelated fields of biological research, including genetics, ecology, biophysics, systematics, geobiology, and paleontology. Current research has widened to cover the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to 4) ___ including sexual selection, genetic drift and biogeography. The newer field of evolutionary developmental biology (“evo-devo“) investigates how embryonic development is controlled, thus creating a wider synthesis that integrates developmental biology with the fields covered by the earlier evolutionary synthesis.

Evolution is the central unifying concept in biology. Biology can be divided in various ways. One way is by the level of biological organization, from molecular to 5) ___, organism to population. An earlier way is by perceived taxonomic group, with fields such as zoology, botany, and microbiology, reflecting what were once seen as the major divisions of life. A third way is by approach, such as field biology, theoretical biology, experimental evolution, and paleontology. These alternative ways of dividing up the subject can be combined with evolutionary biology to create subfields like evolutionary ecology and evolutionary developmental biology. More recently, the merge between the biological science and applied sciences gave birth to new fields that are extensions of evolutionary biology, such as evolutionary robotics, engineering, algorithms, economics, and architecture. The basic mechanisms of evolution are applied directly or indirectly to come up with novel designs or solve problems that are difficult to solve otherwise. The research generated in these applied fields in turn contribute to progress, especially thanks to work on evolution in computer science and engineering fields such as mechanical engineering.

The idea of evolution by natural selection was proposed by Charles 6) ___ in 1859, but evolutionary biology, as an academic discipline in its own right, emerged during the period of the modern synthesis in the 1930's and 1940's. It was not until the 1980's that many universities had departments of evolutionary biology. In the United States, many universities have created departments of molecular and cell biology or ecology and evolutionary biology, in place of the older departments of botany and zoology. Palaeontology is often grouped with earth science. Microbiology too is becoming an evolutionary discipline, now that microbial physiology and genomics are better understood. The quick generation time of bacteria and viruses such as bacteriophages makes it possible to explore evolutionary questions.

Many biologists have contributed to shaping the modern discipline of evolutionary biology. Richard Dawkins of Oxford University, has written many books and papers. His best known book is, The Selfish 7) ___; Theodosius Dobzhansky and E. B. Ford established an empirical research programme. Ronald Fisher, Sewall Wright and J. S. Haldane created a sound theoretical framework. Ernst Mayr in systematics, George Gaylord Simpson in paleontology and G. Ledyard Stebbins in botany helped to form the modern synthesis. James Crow, Richard Lewontin, Dan Hartl, Marcus Feldman, and Brian Charlesworth trained a generation of evolutionary biologists.

Current research in evolutionary biology covers diverse topics and incorporates ideas from diverse areas, such as molecular genetics and computer science.

First, some fields of evolutionary research try to explain phenomena that were poorly accounted for in the modern evolutionary synthesis. These include speciation, the evolution of sexual 8) ___, the evolution of cooperation, the evolution of ageing, and evolvability.

Second, biologists ask the most straightforward evolutionary question: “what happened and when?“. This includes fields such as paleobiology, as well as systematics and phylogenetics.

Third, the modern evolutionary synthesis was devised at a time when nobody understood the molecular basis of genes. Today, evolutionary biologists try to determine the genetic architecture of interesting evolutionary phenomena such as 9) ___ and speciation. They seek answers to questions such as how many genes are involved, how large are the effects of each gene, how interdependent are the effects of different genes, what do the genes do, and what changes happen to them (e.g., point mutations vs. gene duplication or even genome duplication). They try to reconcile the high heritability seen in twin studies with the difficulty in finding which genes are responsible for this heritability using genome-wide association studies. One challenge in studying genetic architecture is that the classical population genetics that catalysed the modern evolutionary synthesis must be updated to take into account modern molecular knowledge. This requires a great deal of mathematical development to relate DNA sequence data to evolutionary theory as part of a theory of molecular evolution. For example, biologists try to infer which genes have been under strong selection by detecting selective sweeps.

Fourth, the modern evolutionary synthesis involved agreement about which forces contribute to evolution, but not about their relative importance. Current research seeks to determine this. Evolutionary forces include natural selection, sexual selection, genetic drift, genetic draft, developmental constraints, mutation bias and biogeography.

An evolutionary approach is key to much current research in organismal biology and ecology, such as in life history theory. Annotation of genes and their function relies heavily on comparative approaches. The field of evolutionary developmental biology (“evo-devo“) investigates how developmental processes work, and compares them in different organisms to determine how they evolved.

Dawkins honors Darwin

Both of Richard Dawkins' parents were interested in natural sciences, and they answered Dawkins's questions in 10) ___ terms. Dawkins describes his childhood as “a normal Anglican upbringing“. He embraced Christianity until halfway through his teenage years, at which point he concluded that the theory of evolution was a better explanation for life's complexity, and ceased believing in a god. Dawkins states: “The main residual reason why I was religious was from being so impressed with the complexity of life and feeling that it had to have a designer, and I think it was when I realised that Darwinism was a far superior explanation that pulled the rug out from under the argument of design. And that left me with nothing.“

ANSWERS: 1) life; 2) homeostasis; 3) biology; 4) evolution; 5) cell; 6) Darwin; 7) Gene; 8) reproduction; 9) adaptation; 10) scientific


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