Explain the paradigm shift that occurred in biology when darwin laid out his theory of evolution

Paradigm shifts are scientific revolutions. In 1962, philosopher Thomas Kuhn wrote that science normally operates by gathering knowledge and filling in details of current theories. When a paradigm shift hits, old established theories collapse and new ideas and understanding take their place. Biology, like other sciences, has its share of paradigm shifts.

Evolutionary Theory

Science writers debate what constitutes a paradigm shift, but there's no denying Darwin's theory of evolution makes the cut. For centuries, science accepted the biblical doctrine that God had designed living species perfectly, so their forms hadn't changed since the Creation. Darwin collected evidence showing that species could change and new species could arise from older ones. He also showed that change was shaped by natural selection, rather than divine decree. It was a radical break with previous scientific thought.

Linnaeus and Taxonomy

Taxonomy is the biological specialty of classifying species and their relationships to each other. Philosophers and scientists were doing taxonomy at least as far back as ancient Greece, but Carl Linnaeus' approach, in the 1700s, marked a paradigm shift. Linnaeus' system created a hierarchy of groups - - kingdom, phylum, class, order, family, genus, species - - to show the complexity of relationships between different creatures. He also established the formula for assigning species Latin names. While later taxonomists worked many changes into Linnaeus' theories, his work remains a major influence.

Gene Transfer

Humans, other animals and plants transmit genes to their descendants through sexual reproduction. Different descendants may carry unique mixes of their parents' chromosomes. In the 20th century, biologists discovered that bacteria have a different method for shuffling their DNA: horizontal gene transfer. Bacteria have the ability to trade genes like baseball cards, creating new genotypes with new capabilities. In microbial horizontal gene transmission, evolution and natural selection work differently - - possibly so differently that the discovery counts as a paradigm shift.

Defining Paradigms

There's no official standard for deciding what counts as a paradigm shift and what is just a really brilliant idea. Gregor Mendel, for example, discovered the existence of genes, which some science historians count as a paradigm shift. Evolutionary biologist Marc Robinson-Rechavi argues online, however, that biologists already knew descendants inherit traits from their ancestors; figuring out the details was important, but not transformative. Robinson-Rechavi believes Darwin's theories are the only true paradigm shift in biology.