A Consequence of human killing of large animals. Rats to inherit the Earth.

Future evolution to make Earth home to variety of rat-like creatures?

What will be the end result of the human tendency to shoot, club, poison, or destroy the habitat of the large mammals, and as they disappear the medium sized mammals as well? Dr Jan Zalasiewicz  at the Geology Department at the University of Leicester (UK) says a likely outcome is that rats and similar animals will fill the land surface of the planet and evolve greatly. Their size, shape, habits, and food sources will change just as mammals evolved from small obscure creatures once the dinosaurs became extinct.

In the future when humans have apparently gone onto the scrap heap of evolutionary dead ends, rats and other quickly reproducing rodents will likely grow much bigger and some become large predators because there is vacant ecospace, he indicated. Other small resilient mammals like domestic cats, rabbits and goats will evolve in various ways too. The professor speculated that the world of rats will be a remarkable diverse place.

Other scientists recently warned of the fact that almost all large carnivores now being threatened is very harmful to the stability of our environment (How the threat to lions, leopards and wolves endangers us all). They could have added large non-carnivores too, such as elephants, rhinos, gorillas, bison. It seems that if an animal is large enough for us to notice to any degree we use it to extinction or breed it into something non-viable unless cared for by humans, e.g., most cattle, domestic sheep.

It is well known that when a large predator disappears, it is replaced by a larger number of smaller predators. An example is the increase in coyotes as the wolves were exterminated.

Here is the story from Science Daily, Rat islands ‘a laboratory of future evolution’: Rats predicted to fill in Earth’s emptying ecospace. It was modified from a news release from the University of Leicester. http://tinyurl.com/kt3blqu






  1. Yvette Avatar

    I can see how rodent numbers could fill and ecological space with the loss of predators, but have a harder time visualizing the evolution of them into larger species. I’m not saying that isn’t possible. Species certainly evolve. I think if it happened it would necessitate other pressures, like losing our mesopredators, in addition to, occurring over geological time.

    Reading this spurred me to read an article I’ve had in my ‘read stack’, “The Rise of the Mesopredator” (Prugh et al.) It’s a great companion article for this discussion, especially with the recent research out on how quickly we’re losing apex predators. It’s free access for anyone interested.


  2. Nancy Avatar

    Interesting. While having some work done on my rig today the subject of rabbits came up from a guy waiting to have an oil change. He said he witnessed a rabbit that had climbed a fence near his house to get to a birdfeeder he’d hung on the fenceline.

    That little episode led to another situation he’d also had, of rabbits under the hood of his car, that had chewed thru wires. (I seem to recall that the plastic surrounding wiring these days are made from organic material?)

    I get mice problems under the hood and in my car ( a fact you have to deal with if you live in the country) but really surprised to hear about someone with rabbit problems, to the same degree. Maybe the coyote derbies and “shoot em whenever” crowd is a really bad idea if you want to keep rodents in check?

    1. WM Avatar


      Rabbits indeed. Perhaps the killer rabbit of Monty Python Crusade lore has been in hiding for centuries and has reappeared near where you live!


      One of my biology professors, long ago, said evolutionary forces would leave the lowly cockroach abundant and in large size similarly to what this University of Leicester professor predicts of rats.

    2. Ralph Maughan Avatar
      Ralph Maughan

      I think we can say that the war on coyotes has yielded almost no benefits other than to a very few people and in a few places. Any local benefit of reducing their population is probably outweighed by harm from increased rodent numbers.

      It’s not that more and more coyotes is good either because, for example, they displace fox. Fox are the primary predator of the white footed mouse which is by far the main reservoir of Lyme Disease.

      Overall in terms of reducing coyote numbers, all the killing has been a total waste. The strong mortality pressure on them coupled with the extermination of the wolf has served to spread the coyote over all of North America. In addition, consider the development of the coywolf. This animal seems to me to be the perfect generalist meso-carnivoire of the Eastern United States. It is also well adapted to suburban life. It will never be displaced by humans in the foreseeable future, and that is probably a good thing too.

      1. Jon Way Avatar

        Very interesting article and theories, thanks for sharing Ralph. I do not think we will ever get rid of the medium sized animals like coyotes, however, so those animals would theoretically be “stock” to evolve from. I would envision coyotes, for example, evolving over 1000s of years into multiple sized canids over time…

        Also, the theory that foxes are more effective predators of mice and hence reduce Lyme disease is questioned, as coyotes may in fact be just as effective as reducing Lyme. Pls see article here:


        And as you indicate, we are literally seeing evolution before our eyes with the coywolf in the Northeast – as this animal is statistically intermediate between coyotes and wolves:


    3. C Andrews Avatar
      C Andrews

      Hi Nancy – good comment. From what I understand in the last few years wires are now being produced with soy-based insulation in vehicles and also used in building interiors and exteriors. Outdoor Christmas lights are now a problem with regard to rabbits (lagomorphs) and rodents. We have now made wires attractive to several creatures.

      1. Nancy Avatar

        “We have now made wires attractive to several creatures”

        C. Andrews – We (humans) have made a lot of things more attractive to wildlife as we march on (unchecked in our own populations) displacing, managing, farming and destroying what’s left of their natural habitat.

  3. LM Avatar

    There was an article in EENEWS alleging that the earth is experiencing its 6th mass extinction. It profiled a photographer who was filming vanishing species. However, it didn’t discuss the geologic / scientific causes. I am curious to know more. Does anybody know the specifics on this claim ?

    1. Barb Rupers Avatar
      Barb Rupers

      Humans have increased the rate of species extinction over that which it was before they evolved on the planet.

    2. Mark L Avatar
      Mark L

      If you google ‘the sixth extinction’ there’s a lot on the subject (minus the X files episodes of the same name). I think there’s a book by Leakey and Lewin that does a good job of covering it.

  4. JEFF E Avatar
    JEFF E

    …and cockroaches. rats will have to have somthing to eat.

  5. Cris Waller Avatar
    Cris Waller

    There actually was a whole book written, years ago, about this possibility and what the evolved rodents and the resulting ecosystems might look like- “After Man: A Zoology of the Future” by Dougal Dixon. http://www.amazon.com/After-Man-A-Zoology-Future/dp/0312011636/

  6. snaildarter Avatar

    rats, roaches, starlings, fleas, bed bugs, jelly fish, pond scum, all do well with humans we have an ugly legacy going forward but it’s not all bad,coyotes, raccoons, gray squirrels, African wild cats aka house cats also do well, so raccoons would evolve into a bear like creatures, cats into all the various felines needed, coyotes and domestic dogs would fill their ecological niches, so if the humans would just go away the planet might recover to a more sensible mix of wild life.

  7. Ida Lupines Avatar
    Ida Lupines

    Future evolution to make Earth home to variety of rat-like creatures?

    Oh, the things that could be inferred here. No offense to the animal, but the two-legged variety are already here, and creating havoc in our government and economy.


Dr. Ralph Maughan is professor emeritus of political science at Idaho State University. He was a Western Watersheds Project Board Member off and on for many years, and was also its President for several years. For a long time he produced Ralph Maughan’s Wolf Report. He was a founder of the Greater Yellowstone Coalition. He and Jackie Johnson Maughan wrote three editions of “Hiking Idaho.” He also wrote “Beyond the Tetons” and “Backpacking Wyoming’s Teton and Washakie Wilderness.” He created and is the administrator of The Wildlife News.

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