[Paleopsych] Ramblin' Wrecks: Study Suggests Humans Can Speed Evolution

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Study Suggests Humans Can Speed Evolution

    Date Released: Tuesday, August 03, 2004
    Source: Georgia Institute of Technology

    It's no secret that life in the 21st century moves at a rapid pace.
    Human inventions such as the Internet, mobile phones and fiber optic
    cable have increased the speed of communication, making it possible
    for someone to be virtually in two places at once. But can humans
    speed up the rate of one of nature's most basic and slowest processes,
    evolution? A study by J. Todd Streelman, new assistant professor of
    biology at the Georgia Institute of Technology suggests that humans
    may have sped up the evolutionary clock for one species of fish.

    Cichlid fish are well known to biologists for their rapid rate of
    evolution. While it takes many animals thousands of years to form new
    species, the cichlids of Africa's Lake Malawi are estimated to have
    formed 1,000 new species in only 500,000 years, lightning speed in
    evolutionary terms. In the 1960s a fish exporter may have unwittingly
    set the stage for an evolutionary explosion when he introduced
    individuals of the species Cynotilapia afra to Mitande Point on the
    lake's Thumbi West Island. As of 1983, the species hadn't budged from
    Mitande Point. But when Streelman, then at the University of New
    Hampshire, Durham, and colleagues went to the island in 2001, they
    found the fish had evolved into two genetically distinct varieties in
    less than 20 years. The study appears in the August 13 edition of
    Molecular Ecology.

    "This is a great example of human-induced evolution in action," said
    Streelman. "It adds to a growing list of cases, including introduced
    salmon, flies and plants, where human disturbance has set the stage
    for contemporary evolution on scales we've not witnessed before."

    The fish have evolved into two genetically distinct and differently
    colored populations, one on the north side of the island, the other on
    the south, said Streelman. Cichlid color patterns are important in
    mate selection, so these distinct markings may promote the evolution
    of new species.

    Whether or not that happens and how long it will take is a question to
    which Streelman is eager to find the answer. "It could be that we'll
    have new species in another 20 years, although this depends on a
    number of factors. Either way, we have a wonderful opportunity to
    follow the evolutionary trajectory of these populations over time. We
    plan to return to the island next July to do further study," he said.
    "Thumbi West will be a valuable place to work for years to come."

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