Once upon a time, 450 million years ago, scavenger fish without teeth or bones roamed the shallow icy waters of Africa which was undergoing an Ice Age. Slowly, over millions of years, they gained teeth and other structures characteristic of more advanced fish. Then, a few thousand years ago, a lake in the (now continental Africa) dried up, and its cichlid-fish inhabitants underwent an explosive burst of speciation. That’s the gist of two stories, one from BBC News and one from National Geographic. The fossil fish story in BBC News emphasizes the claim that this is a “missing link” three times. Professor Richard Aldridge (U. of Leicester) is quoted as saying:“The fossil record confirms that the evolution of fish was a step-wise event,” explained Professor Aldridge. “The various characters that make up a fish, or a vertebrate, didn’t all appear at once – they were added one by one through evolutionary time. These [new] fossils help fill in this pattern of how early vertebrate evolution began.” (Emphasis added in all quotes.)One problem is noted: “These fossils are important because there is a theory that the origins of fish really took place in the northern continents, and then spread south,” he said. “This find [from Southern Africa] dispels that theory.” How fish got to China 80 million years earlier he does not explain. The cichlid fish inhabiting east African lakes today are another matter. In just a few thousand years, according to National Geographic, these freshwater fish “have evolved an astonishing array of forms in Africa.” The high rates of speciation among these fish is “almost beyond belief,” yielding up to 400 species. Evolution apparently has a variable speed control. “The discovery should provide valuable new insights into the march of evolution, which, in the case of cichlids, seems to favor the fast-forward button.”If evolution had a fast-forward button, it would be an intelligently designed machine. These two articles illustrate the extreme flexibility of evolutionary logic, where any data point, no matter how anomalous, can be fit into the tall tale somehow. Contradictions, rather than being disturbing, make the plot thicker and more interesting. Somehow, in an early world with a plethora of unfilled ecological niches, fish took their time evolving over tens of millions of years. Then in a relatively small lake habitat on one continent, Tinkerbell hit the fast-forward button and generated hundreds of species of fish in a geological instant. Evolution marches on.(Visited 13 times, 1 visits today)FacebookTwitterPinterestSave分享0
Bollywood superstar Salman Khan has completed five years on micro-blogging site Twitter.With more than 11 million followers, the 49-year-old may be a little behind with the numbers when compared to the other two Khans – Shah Rukh and Aamir, who have over 12 million followers, but has always kept fans updated by interacting with them on regular basis.“5 yrs on twitter! Thx to arbaaz,” Salman tweeted on Monday. The Dabangg Khan completed five years on Monday. He was trending on Twitter by the keywords #5YearsOfSalmanOnTwitter.Salman, who made his Bollywood debut with 1988 film Biwi Ho To Aisi, also shares a fan following of more than 20 million on Facebook. The actor will next be seen in Kabir Khan’s Bajrangi Bhaijaan, in which he will star opposite Kareena Kapoor Khan.