If large mammals continue to die off, incredibly big rats may one day become the dominant species on Earth. That’s not the plot for an upcoming sci-fi miniseries. “Sharknado” was fantasy, but rats the size of sheep or even cows will likely populate Earth’s future one day, says a scientist from the United Kingdom.
Dr. Jan Zalasiewicz of the University of Leicester’s Department of Geology says that as large mammals continue to go extinct, we should expect to see opportunistic rats step up to wield greater and greater influence in their place.
Rats Will Have No Problem Filling an Ecological Niche
It’s all a matter of available ecospace and the hardy, competitive nature of rats, says Dr. Zalasiewicz.
“Rats are one of the best examples of a species that we have helped spread around the world, and that have successfully adapted to many of the new environments that they found themselves in,” Dr. Zalasiewicz said in a University of Leicester press release.
“They are now on many, if not most, islands around the world – and once there, have proved extraordinarily hard to eradicate. They’re often there for good, essentially. Once there, they have out-competed many native species and at times have driven them to extinction,” he noted. “As a result, ecospace is being emptied – and rats are in a good position to re-fill a significant chunk of it, in the mid to far geological future.”
Watch Dr. Zalasiewicz discuss his prediction here:
Dr. Zalasiewicz notes that during the era of the dinosaurs, mammals existed but were all comparatively small creatures the size of current-day rats and mice. “Only once the dinosaurs were out of the way did these tiny mammals evolve into many different forms, including some very large and impressive ones: brontotheriums, horses, mastodons, mammoths, rhinoceri and more,” he said.
It’s a phenomenon known as “gigantism.” When an ecological niche is left empty by the absence of a larger species, a smaller animal will take advantage of it. It will begin to evolve, growing larger to fill the void simply because it now has the opportunity to do so.
Fifty million years ago, even the ancestor to today’s blue whale was merely a sea mammal about the size of a wolf. Over millions of years, because the vastness of the ocean allowed such growth, they evolved into the much larger mammals we know today.
“Animals will evolve, over time, into whatever designs will enable them to survive and to produce offspring,” Dr. Zalasiewicz noted.
Monstrous rodents would not be new to our planet. Three million years ago, a now-extinct rodent called the Josephoartegasia monesi grew to weigh over a ton. The largest rodent on Earth today is the 17 pound capybara, which lives in South America.
“Rat Islands“ Give Us a Preview of What May Lie Ahead
Rats have managed to reach almost every land mass and island around the world, thanks to the unwitting help of man and his ships and planes. Dr. Zalasiewicz believes that observing how rats evolve on the various islands they inhabit provides a valuable clue to their eventual staying power on Earth.
“Each island that rats are now present on is in effect a laboratory of future evolution, and each will produce different results,” he said. ”So there will be future thin rats, future fat rats, slow and heavy rats, fast and ferocious rats, probably future aquatic rats — the list goes on. Other animals will likely follow the same pattern, such as domestic cats, rabbits, goats and more.”
Bottom line: when Big is gone, Little evolves and becomes the next Big.
The lesson here may be that we need to try harder to preserve our jumbo-sized threatened and endangered species – the elephants, the rhinos, the hippos and the rest. If we don’t, be prepared to cede dominion of the Earth to Gargantua, the Rat King.
Photo credit: Thinkstock
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