How do you evolve a mouse into an elephant? Just add 24 million generations. But you can shrink it back down in just 100,000 generations. This and other eyebrow-raising stories have been told in the secular science media recently.
Monash University published the mousephant story alongside a photo of a jolly professor, Dr Alistair Evans, holding a mouse skull in his fingers with an elephant skull towering behind him. For those who move past the headline, this admission needs a megaphone: “Dr Evans, an evolutionary biologist and Australian Research Fellow, said the study was unique because most previous work had focused on microevolution, the small changes that occur within a species.” The original paper is in PNAS (January 30, 2012, doi: 10.1073/pnas.1120774109).
So, did Prof. Evans actually watch a mouse-sized mammal evolve into an elephant with a controlled lab experiment? No, he just assumed the evolutionary time scale of fossils, and divided the millions of years into generations based on the lifespan of the organisms involved. Well, then, did he use a sliding scale from mouse lifetime to elephant lifetime? If so, was it a linear rate, exponential rate, or chaotic rate? It wouldn’t have mattered, because he didn’t cover a law of nature that makes predictions. “While mammals got steadily bigger after the dinosaurs disappeared,” the article claimed, “the rates at which they did so varied among the groups.” Whales, for instance, evolved into giants at twice the rate of land mammals, while primates seem to have limits on how big they can evolve. (See diagrams on PhysOrg and Live Science, which both dutifully regurgitated the story without criticism.)
For the exceptions, just-so stories were ready in the wings:
- Post-dinosaur era: “It’s a classic story of taking advantage of a new opportunity — the vacant landscape devoid of dinosaurs.”
- Whales: “Dr Erich Fitzgerald, Senior Curator of Vertebrate Palaeontology at Museum Victoria and a co-author, said changes in whale size occurred at twice the rate of land mammals. This is probably because it’s easier to be big in the water – it helps support your weight,” he said….
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