5 Reasons to Bring Back Extinct Animals (And 5 Reasons Not To)

By Breanna Draxler | April 4, 2013 1:36 pm

Mammoth statue in Parc de la Ciutadella in Barcelona, Spain. Image courtesy of Philip Lange/Shutterstock

Would you like to see a real, live wooly mammoth? Or how about a Tasmanian tiger in the flesh? Scientists have already finagled a few ways to resurrect extinct species from their evolutionary graves. Even muckier than the scientific methods themselves, though, are the social, ethical and legal ramifications of so-called de-extinction.

In Science today, two Stanford researchers tackle this tricky topic to parse out exactly what we have to gain and lose from de-extinction technologies. Using the passenger pigeon as a thought experiment, another paper in the same issue looks at the fears and excitement of leaders in the field of genomics.

There are three main ways of bringing back extinct species, according to the Stanford researchers: backbreeding, genetic engineering, and cloning. With backbreeding, scientists use a living species that is genetically similar to the extinct species, and selectively breed it for the traits of the now-extinct species. Genetic engineering depends on existing DNA samples of the extinct species; scientists could bring them back to life by targeting and replacing specific genomic sequences in a closely-related living species. Finally, if viable cell nuclei from the extinct species are available, it can be cloned using a technique called somatic cell nuclear transfer—a tested but as-of-yet unsuccessful method for extinct species.

Based on the current state of the science, the Stanford researchers distill de-extinction down to five pros and five cons:


  • Scientific knowledge: De-extinction could offer insights into evolution and natural resources that are currently unavailable to us.
  • Technological advancement: De-extinction could be a big step forward for genetic engineering.
  • Environmental benefits: Threatened or damaged ecosystems could be restored with the help of certain now-extinct species.
  • Justice: If people pushed plant and animals species into extinction, perhaps we owe it to these species to try and bring them back.
  • Wonder: How cool would it be to see extinct species alive and kicking again?


  • Animal welfare: People could be exploiting animals for solely human purposes, and may cause individuals of the de-extinct species harm.
  • Health: Species could carry retroviruses or pathogens when brought back to life.
  • Environment: De-extinct species would be alien and potentially invasive; their habitats and food sources have changed, so their roles in these changed ecosystems could be too.
  • Political: De-extinction may change priorities in other fields of science, such as medical research and the conservation of currently endangered species.
  • Moral: Is de-extinction playing god, or just plain wrong? It may also have unforeseen consequences.

If an extinct animal were brought back to life in the lab, the authors point out that it would still lack many of a species’ key characteristics, such as epigenetics, environment and social groups. Plus it would bring along with it a number of complicated legalities relating to the Endangered Species Act and patent laws. And that doesn’t even get into the messy world of if and how such resurrections should be regulated.

In the end, both papers seem to draw open-ended conclusions. But if the practice is really as inevitable as it seems, the authors say the most interesting part will be seeing how humanity reacts.

CATEGORIZED UNDER: Environment, Living World, top posts
MORE ABOUT: de-extinction
  • JonFrum

    The anti- reasons are mostly goofy. People with those concerns have the same concerns about all species – or at least the warm and cuddly ones. And playing God? Anyone who signs off on that one should be denied the benefits of modern medicine.

    On the benefit side, the only one that really grabs me is the cool factor. We’re not going to have herds of Mammoths wandering the countryside,,but just to see one would certainly be cool.

  • tomcollins88


    Scientific knowledge: I’m always for more scientific knowledge.

    Technological advancement: I place this the same as #1

    Environmental benefits: Agree if those species were native to the area before.

    Justice: Wholeheartedly agree. How can anyone say that we don’t have an obligation to bring back a species that we (humans) destroyed.

    Wonder: Would I like to see one? Yes. But that’s getting into some murky water.


    Animal welfare: What harm?

    Health: Retroviruses can be filtered out. The technology to do so already exists.

    Environment: Only bring back those species we have caused extinction of.

    Political: No, it won’t.

    Moral: As set in the guidelines I set above, then yes, it’s moral.

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  • Barry Rudd

    Reading the list of pros and cons, it seems to me that the pros have it over the cons. If we can bring them back lets do it.
    The list of objections seems pretty weak.

    Jurassic Park here I come…

    • Nirvana Lee

      Well actually, there won’t be any Jurassic Park because de-extinction
      can only bring back extinct animals from one million years ago at the
      most, and obviously, dinosaurs were extinct longer than one million
      years ago.

      • Wikit

        Dinosaurs are still alive and well… it’s just that we call them something else. Birds. They still carry the DNA of their ancestors.

        • RAYMON CHEN

          BUT… Scientists say that dinosuars DNA is to old to Recreate the animal. *Btw, i do not want to see a living dino by now…*

      • Usoa


        Looking back, I agree with @Wikit .
        Even so, if I agree or not, the truth still stands.
        Also, as our technology is getting better by the second, it does look like we could be seeing Jurassic Park in the best version of 3D, Real Life…

  • xiaoyanzi

    The only objection that I agree with is that there may be many unforeseen consequences to bringing back certain species. We should do our best, case by case, to think the ramifications through, to have a quarantine and observation process that helps ensure the species won’t be invasive or carry some unanticipated biological threat. On the whole though, I think it manageable, and worthwhile, because we will learn and grow our knowledge and be able to use that knowledge save many existing threatened species by increasing their gene pool, making them stronger, or maybe even helping them adapt past whatever is causing their demise.

  • Annonomyse

    Most Pro’s present in this information stand quite true i can’t help but notice, if we bring these extinct species back most will need many new anti-bodies and other immune system structuring. In their current structuring, most of their cells wouldn’t be able to defend themselves. It’s a good possibility that even the common cold/fever could render a species to a death bed

  • Ana P. AlGan

    you don´t need 5 reasons, just rent jurasic park and you´ll see why even if it is awesome is also a bad idea to bring back the extinct.


      AGREED BUT… Scientists say that dinosuars DNA is to old to Recreate the animal. *Btw, i do not want to see a living dino by now…*

  • Kay

    Animals that have been cloned by cross-species nuclear-transfer often die within the first few days the reasons are unclear but it is believed to be premature aging. So even if we did bring back extinct animals the premature aging would cause them to die early on, if we were to bring them back we should further the technology before doing so.
    Bringing back extinct animals would create issues in the food chain as well, because animals like the Woolly Mammoth would be predators and what ever prey they if they are brought back (given if they can adapt to the change in food) would already have predators so that food supply would decrease until one of the predators die off which could be the original predator.
    The most talked about idea for bringing back extinct animals is cloning but there is an issue with that too because clones are a genetic replica of the original animal so what if there was only genetic samples from one gender of that animal? If the animal is cloned it cannot reproduce with its own species. But lets say there is genetic samples from both genders and they are cloned there isn’t a lot of genetic variability even if they reproduce and genetic variability is what allows animals to survive natural selection.
    That’s just some issues.
    In reality it does seem like a cool idea but there are truly more cons than pros.

    • Jenni Caldwell

      you pointed out at least one thing i thought of but aren’t woolly mammoths herbivores.

      • Wayne Higgs

        Personally, I would love to see extinct animals back BUT the arguments for not doing so are viable. Firstly, financially. The money needed to resurrect these animals and to put aside safe environments for them outweighs existing endangered species that should be helped now. Secondly, the proposed method for retrieving these animals from extinction involves taking a similar present day relative’s egg or foetus and replacing certain dna within the embryo. The resulting animal will have some of the extinct animals characteristics, this will be repeated in subsequent generations until the extinct animal is as near to the original as possible. However, is this the extinct animal back from the dead or a genetically engineered version? Thirdly, there are behaviour issues resulting from a freshly returned formerly extinct animal especially with a social animal such as mammoth. Social structure within these animals are honed via generations and releasing these animals would be tantamount to releasing a naive toddler into the wild and expecting them to know how to survive, socialise and thrive.

  • Bob the Jill


  • Bob the Jill

    Pen island

  • gracie prescott

    about the playing god part, he controls everything about everything so if he didn’t wan a species to be brought back to life it wouldn’t happen. I rest my case.

    • rissa

      That is not the point, people have free will, he lets things happen even if he does not want them to. He knows everything that will happen and he knows the decisions people are going to make but he does not make them for you.

    • Zane Gariepy

      i am atheist but I love your argument

      • Canaan Loudermilk

        Hold up……


          oh my god

  • Austin Geggatt


  • Elena

    Actually, I became interested in this topic because I love animals. I am a student and I am currently writing an essay objecting the idea of bringing them back. There is a pretty convincing article on New York Times, quoting professors, scientists, professionals, etc. One reason I would reject this is because it would kill many of our species today to bring back one of the extinct ones.

    • Paige Pittatsis

      What was the name of that article? I am also writing an essay on why we should not bring back extinct species. I am trying to find a primary source and I feel New York Times is good.

  • Tayana Bibbins

    hi i do not want de extinction to happen like bruh

    • Zane Gariepy

      you should make an argument to prove your point why not, or else your claim has no stance

  • Zane Gariepy

    we should totally do this, religious people are just worry that “god” will rain his wrath if we do this. but that will not happen

    • Jason Cooper

      Science is neither good nor evil….its how u apply it that makes it so….in this case….it will be 4 the good of mankind….

  • Jason Cooper

    The main reason would be for a new food source…

  • Jason Cooper

    One mammonth vs. a buffallo….come on now….do the math..

  • Jason Cooper

    If it pans out rite….it will end world hunger….

  • Jason Cooper

    And if u can tame one….u could use it as a tool 2 move objects out the way n an otherwise frozen world…not 2 enslave it…but when needed….it would come n handy 4sure…

  • Jason Cooper

    But then u got those world tyrants who would buy one n the black market….just 2 have one 2 ride just so he can get his jollies up…cuz it makes em feel like he is a god….go figure…

    • Jason Cooper

      Thats a con 2 not create em…

      • Jason Cooper

        2 not bring em bak that is…

    • Jason Cooper

      #there is always that guy….

      • Jason Cooper

        #there is always that guy… who ruins it 4 every1 else….



  • Talayla Yarbrough



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