Evolutionary theory has evolved since Darwin’s publication in 1859. Lamarckism, the idea that body changes can be passed down, has been proven false. The modern synthesis, combining Darwinian natural selection with Mendelian genetics, is the predominant theory. The “gene-centric” view of natural selection proposes organisms are built to pass on genes, not for their own well-being.
Evolutionary theory has come a long way since Charles Darwin published The Origin of Species in 1859. Prior to its publication, and in direct competition, Jean-Bapiste Lamarck was promulgating a well-known flawed variant of evolutionary theory: Lamarckism or the Lamarckian evolution. Lamarck thought that body changes over the course of a lifetime could be passed down to ancestors as long as they were common to both sexes of the species.
For example, his explanation of why a giraffe has a long neck is because the giraffe had a history of ancestors increasingly reaching for high leaves in a tree, and offspring were born with larger necks as a result. . This theory of evolution has been shown to be false: the genetic difference between parents and children can be explained entirely by their genes and requires no reference to the parents’ daily lives.
The most important theory of evolution is known as the modern synthesis or neo-Darwinian synthesis, which is the combination of Darwinian natural selection with Mendelian genetics and Thomas Morgan’s theory of chromosomal inheritance. This theory continues to be predominant to this day, with some minor differences.
Mendel, a German monk who lived about the same time as Darwin but whose work was not rediscovered until 1900, experimented extensively with plants and discovered the concepts of alleles (different versions of the same gene), dominant and recessive traits, and that the expression of different traits are exclusive to each other. Darwinian evolution and natural selection are just the idea that life evolves based on random mutations and selection pressures on individuals trying to reproduce.
In the 1960s it became necessary to introduce the “gene-centric” view of natural selection, not really an independent theory but more of a footnote on the modern synthesis. Around this time, some biologists erroneously thought that individuals evolved traits for the good of their species or group.
To correct this, it was necessary to propose a gene-centric view of evolution, in which organisms are seen as the “survival machines” of genes, built solely for the sole purpose of passing on those genes. For example, a gene may opt for an organism with a shorter life span and faster reproductive cycle if that is what evolution chooses. Genes don’t care about the well-being of their shells, the organism. This is probably the most sophisticated and recent iteration in the ongoing evolution of evolutionary theory.
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