I'd like to know if a planet without any animals except humans can exist. The cause of this absence of other species could be anything but the humans should not have any social interaction with something else than humans for centuries.

What would be the effects on the society? I guess that humans can live without any animal nutrients but can the global ecosystem be rich enough for humans without interactions with other species?

Do Humans have to be highly developed in order to live in this kind of planet or do you think people from Middle Ages could live in it?

How would this kind of world affect our personality? Humans tend to feel close to the animals. Would a lack of other animals cause us emotional distress?

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    $\begingroup$ I recommend you to narrow your question a bit in order to help those who will answer. Right now, you ask for several and very different things. To begin with, you have two questions here: ''What would be the effects on the society? I guess that humans can live without any animal nutrients but can the global ecosystem be rich enough for humans without interactions with other species?''. One is about the social effect of human cultures and the other is about the ecosystem. $\endgroup$ – Vincent Mar 20 '15 at 15:26
  • $\begingroup$ I remember reading about something like this once... A species had wiped out its home planet and all animal life was a genetic modification/variant of the sentient species... $\endgroup$ – Serban Tanasa Apr 1 '15 at 0:42
  • $\begingroup$ Are you suggesting the humans are originally from that planet, or recently transplanted there? If it is the former, then absolutely not: humans can not have evolved directly from a plant. $\endgroup$ – Mikey May 28 '15 at 19:06

Not having insects would be a big problem - a lot of plants rely on them for pollination for example. That can be worked around, but plant life would be very different - definitely no flowers.

For anything big enough for humans to really interact with, you just need to fill those roles with humans. A human slave isn't as strong as a horse, but enough of them will get the job done.

Actually caring what happens to animals (or most other humans for that matter) is a very recent innovation in our society.

  • $\begingroup$ Not to mention the fact that less animals means less food. Everyone would be forced to be vegetarian, and there would be a very large strain on such plants and especially fruit bearing trees. $\endgroup$ – White Fang Mar 19 '16 at 2:15
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    $\begingroup$ @WhiteFang: On the contrary, less animals means MORE food. You get a lot less energy out of an animal's meat than the energy originally contained in the plants it ate (roughly 90% of the energy is lost when converting it into meat). Granted, animals like cows can eat plants that we can't (grass, for instance) but these days most farm animals are fed wheat or corn anyway. $\endgroup$ – IndigoFenix Mar 20 '16 at 8:04

This is a very good question. In my opinion, humans would definitely die off eventually without animals. Animals play a big part in our society. Here are some notes that I made on this topic:

  • Some animals that we cannot live without are bees, bats, butterflies, fish, worms, plankton, wasps and rats
  • The connection between humans and animals is one of the most fundamental bonds that human beings experience
  • Humans have interacted closely with animals for thousands of years
  • Animals provide many beneficial things to humans and without them, even with plants, humans would eventually go extinct because the ecosystem just lost a huge chunk
  • The human-animal connection is: “A mutually beneficial and dynamic relationship between people and animals that is influenced by behaviors that are essential to the health and well-being of both. This includes, but is not limited to, emotional, psychological, and physical interactions of people, animals, and the environment. The veterinarian's role in the human-animal bond is to maximize the potentials of this relationship between people and animals.”
  • Animals are part of almost everything that we do
  • Pets are good for people. Pets give people a loving companion to care for. They encourage conversation and laughter. They cause us to exercise and offer an antidote for loneliness. They teach children responsibility. By caring for pets, pet owners benefit, too.
  • Pets can also boost infant immunity to infections, help with mental health disorders by affecting brain chemistry, and lower blood pressure.
  • Animals and humans are a powerful two way bond.
  • A con about animals would be that wild animals are unpredictable and there have been many deaths with wild animals before in the past
  • $\begingroup$ This does not answer the question. The first bullet point is the only one that directly discusses the original question, but even then it answers "Can we live without animals?" with "We cannot live without X, Y, and Z," apparently as if those animals all perform some special, irreplaceable function, without stating what that function is. The rest of the points seem to suggest that quality of life would decline, but it does not suggest that life would cease or be impossible; I can live just fine without a pet, for example. Please elaborate first point. $\endgroup$ – Loduwijk Jul 19 '17 at 20:06

It just came to my mind that that situation can happen.
I guess that lots of sci-fi stories tell about humans landing on some planets that flora would consist of plant-like beings.
Given that all of these 'beings' are coexisting together filling every step of ecosystem ladder (whatever it may be), then human 'invaders' would start living in such world.
Now, let's see what the outcome will be:

  • at first humans must to adapt to new ecosystem and find what these 'plants' will consist of;
  • second step would be identifying proper species that would serve as food and what it will be like to live on this kind of food;
  • if we assume that previous step is sufficient for our humans to survive, they will live that way as long as this 'new food' would not harm them;
  • as decades and centuries pass, human gastrointestinal tract would change and adapt to this new diet; planet's ecosystem would also change (in what way?) as there is a 'new player' in the game of life;

Of course, all of this can be possible and valid as an answer to Your question IF we would classify 'native plants' as plants. For human newcomers they may seem static, rooted to the ground, in various sizes, colors, scents. The way of reproducting can also be not-requiring other 'animalish' species (like bees for that matter). They don't need to be hunted down (they don't move), they do not defend themselves - these can impact on less-aggressive social behaviours in human community.

Simply put, I would say that in world given above humans may not need that effort of tooth-and-claw and therefore may result in smaller amount of physical aggression between people.


Ditto comments about pollinators. The impact of large animals on ecosystems is profound. It's been found that their feces of large mammals are crucial to recycling nutrients in terrestrial and marine ecosystems. Also, I think humans would be sad and if we are ever forced to leave earth we will bring whatever animal species we have not destroyed with us.

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    $\begingroup$ That was a very nice answer Bill. And welcome to the site :) If you add more detail and references to your answers, it would make them more helpful and credible to the readers :) $\endgroup$ – Youstay Igo Mar 19 '16 at 6:24

Many people in large cities already live without interacting much with animals, so psychologically it wouldn't be too big of a deal. Maybe some people would be slightly less happy and not know why but on the grand scheme of things it wouldn't be that noticeable.

Ecology, on the other hand, has to be completely different, many many plants coevolved with animals and insects and rely heavily on them for seed spreading, fertilized and so on. Many (if not most ) Earth plants will definitely die if animals disappeared, and humans will follow them. Nut on a different planet it should be possible.


We use a surprisingly large amount of animal products in industry. Wool, leather, fat, tallow, glue, gelatin. Maybe our advanced early 21st century industry can adapt the production to a world with no animals, but in medieval times they would have been totally stimied. They simply did not have anything which could replace wool, or animal glue, or animal fat, or leather. Nothing. There were no artificial fibers, no plastics, no epoxy glue, no kerosene lamps...

On the other hand I cannot understand a world without cows and pigs and sheep and chicken. We raise them in the billions -- why would we stop? When we colonise an alien world we bring our domestic species with us. If we can eat the local plants then so can a pig...

  • $\begingroup$ This answer appears to be factually incorrect. Substitutes for many of those items have been used since before 21st century technology/industry, and even before 20th century technology. Cotton is a good wool substitute. There are some substitutes for leather depending on the specific use. There are various plant byproducts which have been used as glue; I myself have used tree sap glue, as some trees in my area have extremely sticky, gluey sap. If you are willing to stretch a bit further, there are other plant substitutes as well; Q did say "is it possible," not "would it work just as well" $\endgroup$ – Loduwijk Jul 19 '17 at 20:16
  • $\begingroup$ @Aaron: The question is about a medieval economy. The killer is leather. In medieval times it was the only material approximating our plastics -- it could be molded into shape and keep that shape. Bone glue comes second. Then fat, tallow, wool. Cotton cannot substitute for wool, they have very different properties; and in medieval times cotton was about as expensive as silk. To understand the importance of animal products for a medieval economy you must consider not only the basic properties of the material but also its availability to the small self-sufficient estates of the Middle Ages. $\endgroup$ – AlexP Jul 19 '17 at 21:21
  • $\begingroup$ Question is "is such a world possible?" Leather is a hurdle, yes, one which I did not call you out on fully. I will grant you leather. Cotton is a wool substitute for clothing and personal insulation, whether expensive in our medieval time or not; did you have some other use in mind? I suppose it depends on where you're coming from; I'm thinking "can we have a subsistence society?" tribal-like. I didn't down-vote though, and because of your leather point I won't. I still think your wording is strong enough to be factually incorrect and close to -1. Maybe I'm being nit-picky about wording. $\endgroup$ – Loduwijk Jul 19 '17 at 21:53

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