Is evolution predictable?

Evolution has been a controversial subject. The history of Evolution is divided into four eras based on Evolution of Evolutionary theories,

1. Pre-Darwinian period (before publication of "On the Origin of Species" in 1859) : Lamarckian evolutionary theory was dominant in this era.

2. 1859-1880: Soon after publication of, "On the Origin of Species", it replaced the Lamaeckian evolutionary theory, though majority accepted it and some reacted to it but still Darwinism was dominant.

3. Eclipse of Darwinism (1880- 1930): This is a period when other rival evolutionary theories emerged. Mendelianism (Genetics) was dominant evolutionary thoery of this era.

4. Modern synthesis (1940 onward): The marriage between Darwinism and Mendelianism: In this era, geneticists, organismal biologists and statisticians fused their works to create modern synthesis of evolutionary theory.

Though, it is an era of modern synthesis but controversies emerge to question existing explanations of evolution. Science never cease devlopment of new theories and explanation so learning controversies make you not blindly accept explanations in name of Science..
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It is generally believed that genetic drift is random, however David L. Stern from department of Ecology and Evolutionary Biology, Howard Hughs Medical Institute, Princeton University and Virginie Orgogozo from CRNS, Universite Pierre et Marie Curie, Paris, write, "Ever since the integration of Mendelian genetics into evolutionary biology in the early 20th century, evolutionary geneticists have for the most part treated genes and mutations as generic entities. However, recent observations indicate that all genes are not equal in the eyes of evolution. Evolutionarily relevant mutations tend to accumulate in hotspot genes and at specific positions within genes. Genetic evolution is constrained by gene function, the structure of genetic networks, and population biology. The genetic basis of evolution may be predictable to some extent, and further understanding of this predictability requires incorporation of the specific functions and characteristics of genes into evolutionary theory."

Reference:

Science 6 February 2009: Vol. 323. no. 5915, pp. 746 – 751, DOI: 10.1126/science.1158997