Changes

== Origins ==

== Origins ==

[[File:Whale_evolution.jpg]]The question of how whales and their relatives could have evolved from terrestrial [[mammal]]s has taxed evolutionary biologists since [[Charles Darwin|Darwin's]] suggestion that they may have evolved from ancient bears. <blockquote>"In North America the black bear was seen . . . swimming for hours with widely open mouth, thus catching, like a whale, insects in the water. Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale."</blockquote><ref>Charles Darwin, [http://www.gutenberg.org/ebooks/1228 Origin of species] 1st edition </ref>

The question of how whales and their relatives could have evolved from terrestrial [[mammal]]s has taxed evolutionary biologists since [[Charles Darwin|Darwin's]] suggestion that they may have evolved from ancient bears. <blockquote>"In North America the black bear was seen . . . swimming for hours with widely open mouth, thus catching, like a whale, insects in the water. Even in so extreme a case as this, if the supply of insects were constant, and if better adapted competitors did not already exist in the country, I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale."</blockquote><ref>Charles Darwin, [http://www.gutenberg.org/ebooks/1228 Origin of species] 1st edition </ref>

In more recent times molecular and fossil evidence has been used to suggest that modern whales and their relatives arose from ancient [[Artiodactyla|artiodactyls]] (even-toed ungulates) with the closest living relative of all whales being [[hippopotamus|hippopotami]].<ref>[http://www.redorbit.com/news/science/41080/molecular_clock_divergence_estimates_and_the_fossil_record_of_cetartiodactyla/index.html] Theodore, JM (2004) Molecular Clock Divergence Estimates And The Fossil Record Of Cetartiodactyla <i> The Journal Of Paleontology</i> <b>78</b>:39-44</ref>

In more recent times molecular and fossil evidence has been used to suggest that modern whales and their relatives arose from ancient [[Artiodactyla|artiodactyls]] (even-toed ungulates) with the closest living relative of all whales being [[hippopotamus|hippopotami]].<ref>[http://www.redorbit.com/news/science/41080/molecular_clock_divergence_estimates_and_the_fossil_record_of_cetartiodactyla/index.html] Theodore, JM (2004) Molecular Clock Divergence Estimates And The Fossil Record Of Cetartiodactyla <i> The Journal Of Paleontology</i> <b>78</b>:39-44</ref>

This kinship has been termed the whippo hypothesis.<ref>http://www.sciencenews.org/pages/pdfs/data/1999/15619/15619-10.pdf</ref>

This kinship has been termed the whippo hypothesis.<ref>http://www.sciencenews.org/pages/pdfs/data/1999/15619/15619-10.pdf</ref>