# Is it possible to have a habitable planet unsuitable for agriculture?

I want to have a planet similar to earth with 45% axial tilt when hunter gatherers have an advantage over agriculture. The only thing I could think of is far north(Siberia, Alaska) & Sahara desert, even there people keep animals (reindeer & camels) so I guess nomadic herding can't be completely eliminated.

What kind of features should planet have to make agriculture unfeasible while still being able to support life? I wan't a plausible explanation why farmers can't out-compete the hunter gatherers.

Edit:

The lack of agriculture is due to being a winning strategy, not due to cultural reasons. If some band/tribe of humans could out-compete the others it would become a dominant one. The hunters will adapt or be driven off.

CONCLUSION

After thinking about the answers and reading this thread I believe that only Arid planet with Erratic rainfall could do what I want. But that planet would unlikely evolve complex life.

THINGS THAT I THINK WON'T WORK:

Magical things, reality-check tag excludes such things.

Undomesticable plants. If humans could live as hunter-gatherers they must have some food to eat. And some sources would be better then the other. Nothing prevents them to help the better sources to become more abundant. Sooner or later domestication will happen.

Undomesticable animals. We haven't domesticated American Bison nor Zebra, because we already have good cattle, why spend time on another one. If all we had is Buffaloes and Zebras I'm pretty sure that we'll find a way to have a herds of Buffaloes and that we'll bring them to pasture while riding Zebras. See this for recent example

Dumb apex predator. Humans dealt through history with many scary things check this excellent answer about Megalodon

You and I might be computer-bound bums with poor vision, but our ancestors were super-intelligent, awesomely effective pack hunters. No creature alive, from the a blue whale to army ants stood a chance against a pack of cave men.

Or even against T-Rex

Smart apex predator. I think this lead us to two intelligent species evolving on the same planet around same time, possible but very unlikely

• Very aggressive insects which target concentrations of plants. Or more likely still, very poor soil conditions, and a lack of understanding of how to overcome them. – AndreiROM Oct 13 '16 at 19:02
• @AndreiROM insects looks kinda deus ex machina but poor soil is a good one. But couldn't soil be improved? – Platypus Oct 13 '16 at 19:05
• Improving the soil is actually fairly "modern" knowledge. Same thing with rotating crops. Even irrigation. Depending on the level of your society they might just not have developed this knowledge yet. Lemme write up an answer. – AndreiROM Oct 13 '16 at 19:11
• @drewbenn Not an option because Nash equilibrium gives advantage to band/tribe which decides to settle, 20 weak farmers could easily beat 1 strong hunter. – Platypus Oct 13 '16 at 19:54
• You might be over complicating things, there is nothing "inevitable" about domestication of plants or animals your answer may be as simple as, agriculture was just never invented. – Justin Ohms Oct 14 '16 at 19:00

Get rid of the "gathers" part of "hunter-gather" and make the people to be carnivorous; At least like wolves are, if not obligate carnivores. That would greatly increase the gap between where agriculture becomes more advantageous than a nomadic hunting/herding lifestyle.

Most likely they would still pick up skill and knowledge to care for the herd, and even some amount of ownership of a herd, even if the animals they live off can't be domesticated (see American Bison), such as spreading the grassland via clearing brush/forest land, protecting the herd from other predators, promoting the food sources the herd lives on, and killing off animals that eat the same food source.

• Very good idea, I was nearly throwing the towel. – Platypus Oct 13 '16 at 22:03
• A sub-society that farmed for food for their animals could maintain a higher population density than a purely nomadic one. Irrigation and land management could increase yield many fold over grasslands. And once you are improving a location, staying there to defend it becomes optimal... – Yakk Oct 14 '16 at 0:38
• Assuming one already has the ability to contain the animals in one location (and/or domesticate them) and that the farming is able to produce more food for the animals and maintain enough animals with farming the food to support the population; then yes, eventually. – John_H Oct 14 '16 at 2:08
• @Yakk True, but note that it's vastly less efficient than eating the produce directly. It's not a coincidence that it took us so long to start feeding animals with our own produce - just letting animals graze was much cheaper, especially in warmer climates and before the three-field system. The number thrown around most often is you lose 90% for each extra layer of indirection - and early agriculture (with the exception of the extremely rich areas like Mesopotamia and the Nile) was barely enough to feed people. It took quite a long time for agriculture to be the better option overall. – Luaan Oct 14 '16 at 13:53
• I like this answer, but I kinda feel like the further down it goes, the more these humanoids become ranchers, which are basically 'animal farmers'. Especially around clearing the land and promoting food sources for their animals. That's basically agriculture. To me, obligate carnivores with some kind of territorial arrangement and a semi-managed prey source(s) would be enough to refrain from any agriculture at all. It also goes more inline with the actual question: perhaps this planet's flora cannot be easily managed with clearing and promoting, e.g. making it unsuitable for agriculture. – coblr Oct 14 '16 at 17:32

Imagine a planet with two life layers:

Outer space
...
Rather dense atmosphere with floating moss performing photosythesis
...
Hard earth crust, with not enough light for efficient photosynthesis


Every once in a while, a huge (Paris-sized) lump of moss gets too heavy and falls down, triggering all herbivore animals 1000 kilometers around to wake up from hibernation and go eat the whole of it before going back to hibernation. If not eaten within a month, the moss would go stale.

Life has evolved from moss into animals that suit this environment:

• Vibration sensor to perfectly feel very subtle vibrations in the ground, letting them know the direction in which the felt moss is, even if very far away. This sense is active even during hibernation.
• Ability to travel 1000 kilometers while surviving only on their fat reserves.
• Hibernation that can last for 3 months (on average, moss falls within 1000 kilometers about once per month).
• There is not much light, so animals see using other senses, especially vibration but also other senses that night-animals on Earth have too.

With no constant supply of moss, farming is not an option. Our heroes have three options, none of them being agriculture:

• Search for hibernating animals to kill and eat them.
• When moss falls down nearby, travel to it and easily kill and eat the animals that have no choice but to converge there.
• Just eat the moss like the other animals.
• They might also be able to just eat the moss; that would be the "gatherer" portion. – DonyorM Oct 15 '16 at 2:21
• @DonyorM: Indeed. Actually most animals on this planet could be considered gatherers, if I understand the word "gatherer" correctly. – Nicolas Raoul Oct 17 '16 at 2:16

A meta answer for any question of the form "How can I have a planet where civilization doesn't look like ours?" is "Read Jared Diamond's book Guns, Germs and Steel and figure out what links to cut to stop us developing as we did.

Our agriculture is primarily based around a very few grains (wheat, rice and, to a lesser extent, barley, maize and millet) and a very few animals (almost entirely cattle, pigs, sheep, chickens). So, if you can stop those things working, you've ruled out agriculture that bears any real similarity to ours.

One option that comes to mind is to have an undomesticatable species with a cow-like appetite. Note that undomesticatable doesn't have to mean a huge difference: horses and zebras are very similar but nobody domesticated the zebra. With such a species in your world, grain-based agriculture ceases to be viable, because the zebra-cows will eat all your crops. Likewise, grazing-based agriculture doesn't seem to work, since the zebra-cows will eat all the stuff the cow-cows were supposed to eat. You could still keep chickens but they're unlikely to provide you with enough food on their own so, again, that's not a viable system of agriculture.

• That's why I suggest you read Diamond. He explains why it's not enough to domesticate any old plant. For example, you need something that can be stored through the winter. Essentially all human civilizations have been based around a small number of grains and a small number of domesticated animals, in part because most of the other options don't work. – David Richerby Oct 14 '16 at 12:16
• @Platypus I concur with David. It's rather extensively discussed in an entire chapter of the source (Guns, Germs and Steel). You assume that some plants would replace wheat and rice, but the evidence says otherwise. Take a look at Australia or New Zealand - they just didn't go with "whatever they got", they simply stayed as hunter-gatherers. With agriculture, they would likely had lower output and lower life expectancy. – kubanczyk Oct 14 '16 at 12:19
• @Platypus Australia an outlier? No, it's evidence from the real world. It's an entire colonized continent that doesn't fit an assumption that Homo Sapiens will end up in agriculture no matter how poor plants are available locally. If your entire world has the same native flora as Australia - bingo, no agriculture. QED. – kubanczyk Oct 14 '16 at 14:02
• Note that although you can grow crops in marsian soil, they might pick up too many perchlorates to eat. Australian agriculture mainly is based on imported species. If it turned out that only certain plants/animals native to Australia had that ability to neutralise local toxins in the soil, you wouldn't want to farm wheat and cows even if the planet was otherwise exactly like earth (or indeed a future polluted earth) space.com/21554-mars-toxic-perchlorate-chemicals.html – gmatht Oct 15 '16 at 3:58
• @DavidRicherby, if there is a dormancy season (winter), there will be plants that can be stored over winter, because the plants themselves need the seeds to last, while if there isn't, you don't need it either. Papua New Guinea is an example of that. On the highland, there was developed agriculture by the time Europeans arrived, but without anything that could be stored for extended periods of time. This did have effect on the society—it was only loosely organised as with little to steal chieftains were not needed for enforcing order so there were none. – Jan Hudec Oct 15 '16 at 18:44

The choice to prefer hunting and gathering over agriculture and settling down can be driven several factors:

Culture

In a culture valuing feats of strength, and cunning, especially hunting prowess, settling down might seem like a coward's move. Of course this doesn't necessarily stop entire populations from eventually adopting this lifestyle so ...

Severe Weather Patterns

Perhaps this world is ravaged by travelling storms which destroy everything in their path, and travel very unpredictable paths. Anyone not on the move, or able to get out of their way fast is doomed.

Roaming Foes

Similar to the unpredictable storms, maybe a race of predators roams the land, guided by some unknown force (the stars in the sky, the phases of the moon, etc.), and it's easier to avoid them by running, than to face them.

Agriculture is Hard

Getting a good yield from a crop can be very tough work. Maybe your world suffers from very poor soil conditions, which are simply not conducive to agriculture, and your characters haven't quite figured out the knack yet (crop rotation, fertilizing the fields, etc.).

• If the soil conditions are so poor, how can there be enough vegetation to feed wild animals? – Mike Scott Oct 13 '16 at 19:23
• @mikescott - whatever feeds the animals might be poisonous to the humans. For example, humans can't extract nutrients from grass. Sheep, however, do. They eat the grass, then we eat them. If grass is readily available, that doesn't help us except that we might be able to keep more sheep. Maybe most plants are simply not nourishing or even poisonous to these people, and they depend on getting their food from the small number of plants which are good for them, and from hunting. – AndreiROM Oct 13 '16 at 19:25
• If whatever feeds the animals poisons humans, why wouldn't the animals just evolve the ability to keep those poisons in their flesh, thus making them immune to predation by humans? – kingledion Oct 13 '16 at 19:26
• @kingledion Won't humans select for less poisonous animals? – Platypus Oct 13 '16 at 19:30
• @Platypus Only if they have already domesticated said animals. I don't see a path to domesticating a poisonous animal. – kingledion Oct 13 '16 at 19:47

Two points to compliment the other answers:

First, the planet could simply have no habitable expanses of easy-to-farm terrain, or soil conditions that adequately supported plant life. If everyone had to live in rugged, mountainous areas, then developing agriculture on a large enough scale to completely outpace gathering would be extremely laborious. For example, consider Mesoamerican populations that flourished in mountainous regions hosting plenty of undomesticated plant and animal life but lacking agriculturally-conducive topography.

Second, presenting a lack of animal species to use as potential beasts of burden could be a notable factor. (Relatedly, nomadic societies don't necessarily require domesticated animals to thrive.)

Historically, the main reason that neither hunting nor herding were developed in the Upper Paleolithic era from ca. 40kya to 10kya (at which point it began) was that global average temperature was varying dramatically over periods of two or three generations. So, your children or grandchildren couldn't grow the same crops or herd the same animals as you did without a major relocation. Reinventing agriculture every two or three generations was just too hard.

As the linked Supplement to a journal article explains:

Differences in temperature (Centigrade) are about 1.2 times the difference in the δ18O signal shown in Fig. S1 (2). The data indicate that changes in mean temperature as great as 8 degrees (C) occurred over time spans as short as two centuries. By way of comparison, the Little Ice Age that devastated parts of early modern Europe experienced a fall in average temperatures of one or two degrees, and the dramatic warming of the last century raised average temperatures by one degree, comparing the unprecedentedly hot 1990s with a century earlier (3, 4). The variability of climate during the late Pleistocene required high levels of geographical mobility, which was an impediment to any substantial investments in tree crops or field preparation or even stores and storage facilities. The scale and pace of climate change is truly extra ordinary: for example δ18O signals from sea cores indicate that between 25 and 60 ka, variations in sea surface temperature of 3o – 5oC occurred over periods of 70 years or less in the Santa Barbra Basin, California (5) (sea surface temperatures today are about this different between the Santa Barbara Basin and northern Vancouver Island). Think about the frequency of moves and the distances that early humans may have traveled. A change of 9 degrees Centigrade in the course of a millennium appears to have been common prior to the Holocene. That's the difference in the average daily temperature in Cape Town and Mombasa 4 thousand kilometers to the north. While humans and the wild species on which they depended could of course adapt to a few degrees change in temperature, we infer that the distances covered and frequency of moves must discouraged the kinds of investment that farming requires.

Climate variability (Left) is an indicator of the 100-y maximum difference in surface temperature measured by levels of δ18O from Greenland ice cores (SI Appendix). A value of 4 on the vertical axis indicates a difference in average temperature over a 100-y period equal to about 5 °C.!IMAGE

• Very good answer, ohwilleke, though did you truly mean to say that hunting was not developed before 10kya? (Certainly it was!) – Dan Oct 15 '16 at 17:43
• Another coinciding factor that seems appropriate to mention here was that population densities were not high enough yet to make agriculture a more appealing strategy than hunting/gathering. – Dan Oct 15 '16 at 17:45

Your scenario appears to be self limiting.

Primarily this is because having animals to hunt implies enough fuel for them live, grow and breed.

While some animals eat other animals, the vast majority of vertebrates eat plants. If the conditions on your planet are not conducive to farmed plants I see no way they could be conducive to the plant life necessary to support complex animal life. No complex animal life, no humans.

The essential problem is that the environmental factors that would make farming unsustainable would also make complex life extremely unlikely.

Recommendation:

I am not sure what kind of world you are trying to create (Real/Fantasy/Past/Modern/Future ...etc) but weather related environmental stresses are unrealistic for the reasons mentioned above.

Now you do have a couple options that could work to greater and lesser degrees:

• Predators. Roaming predators that have no trouble overcoming humans. If you have to stay on the move you can't really farm

• Socio-cultural reasons. Its tough to imagine and is definitely cheating, but hypothetically you could claim social and cultural norms. The problem is that amongst hunter/gatherers norms are going to be much simpler than among settled peoples. Rules and taboos are much more likely to develop in a society where you aren't working on a daily basis to survive. Survival is the rule.

The main exception that comes to mind would be a world with active spirits/deities. If god makes you do something...

• Some other necessary resource that is rare and spread out...this could be some alternate humanoid nutrition requirement.

So in short it can be done, but you will have to work it out really well to make it not seem contrived.

• How you gonna farm in the arid place with unpredictable weather? That happens in many places on Earth, I just want to have that over the whole planet. – Platypus Oct 13 '16 at 21:09
• @Platypus right but if that happens over the entire planet odds are complex life doesn't come to be. – James Oct 13 '16 at 21:41

Plant species all have inconsistent phenotypes. On Earth, if you plant an apple, it grows into a tree that produces more apples. But open up the DNA to wider variation -- an apple gives rise to a vine, or a walnut tree, or a tulip. The plants of the world all interbreed easily, and even careful pollination isn't stable thanks to virus-like exchange of genetic material.

This means that if you find a tasty tree, you can't necessarily breed more of them. So your tribe is constantly on the hunt for more tasty trees.

• I don't think genetics works that way. – Platypus Oct 14 '16 at 12:58
• It can. Investigate "polytypic species". It doesn't typically in most species, but a complex enough genome can be constructed to make predictions about descendants' phenotypes essentially unpredictable, with wide variance. – SRM Oct 14 '16 at 14:34
• Nice idea, but unlikely for all species, humans would just focus on the non polytypic ones and domesticate few of them – Platypus Oct 14 '16 at 14:59
• Only if the planet has any. You wanted a plausible reason for no agriculture. This works. I understand if you want to go a different route for your tale. – SRM Oct 14 '16 at 16:19

First off, nomadic herding (provided the presence of suitable domesticated animals) will probably always be better than hunting and gathering. So if you really won't want domestication, provide non-domesticatable animals.

Secondly, agriculture is an even better advantage in the long run. Any agricultural society is eventually going to outbreed hunter-gatherers, so the only way to prevent agriculture is to remove domesticated plants. Look at places where no domesticated plants developed at all. Now, most places do have domesticated plants of some sort so the environments to go with are high mountains, deserts (without Nile-like rivers), tundra, and mangroves.

# Examples

An example could be: a world with no ocean and low air pressure and temperatures, simulating high mountains. In the lower areas are moist, foggy pine and bamboo forests populated by a range of mammals and primates, in the upper areas seasonal meadows with ungulates and carnivores. Eventually some of the primates leave the safety of the trees to wander the upper plateau in the summer, specializing in edible fungus and the odd carrion. Soon these apes develop tool use to deal with cold nights, and learn to hunt on their own. Its only a matter of time before they domesticate the creatures of the plateau as the supreme herders of the planet.

Or, to truly remove domesticated species: A hyper-arid world where the only significant precipitation are heavy monsoon rains in mangrove swamps at the edge of tropical seas. The food chains here are dominated by fish-eating reptiles and reptilian apex predators; the only mammals are bats and tree living primates eating insects and fruit. One branch of primates made its way out of the trees into the dry steppes beyond the edge of the swamps where they subside on drought resistant tubers and scavenging corpses of the large terrestrial reptiles. Soon the walking apes learn to make bows and become the apex predators themselves.

• I know that agriculture is an advantage, that I want to prevent it as winnable strategy. I don't think that your examples will work on a long run. If you have bamboo forest why not keeping Panda as livestock – Platypus Oct 13 '16 at 19:58
• @Platypus Because pandas don't screw the save the species, how are you going to breed animals that won't? – kingledion Oct 13 '16 at 22:36
• Well Bamboo lemur or Bamboo rats instead ? – Platypus Oct 13 '16 at 22:39
• @Platypus I picked a bamboo forest because no animals native to bamboo forests have ever been historically domesticated, unless they are also native to other parts of the world and domesticated there first (like cats). – kingledion Oct 13 '16 at 22:42
• For your second example, does fishing count as hunter-gathering? Then you can even let all the land-dwelling plants go extinct and just have your tribe live of the sea. – Sumyrda Oct 14 '16 at 21:57

The planet could be a giant prairie. Grass can grow, but not much else. Hence why humans have to eat grazing animals, instead of plants directly. Similarly, if humans rip up the prairie and plant crops, you get a dustbowl that grows out of proportion and destroys a everything.

Or, whenever humans settle down in one place, endemic disease eventually destroys the population and forces a return to hunter-gathering.

Edit: If you downvoted, why don't you take a trip down to your nearest grassland, and try and eke out a living by eating seeds, and then come back and tell me how easy it is.

• Wheat, rye, barley, oats, rice and maize are all kinds of grass. If grass can grow, then you can cultivate grain crops. – Mike Scott Oct 13 '16 at 19:22
• @Mike Scott, cultivated crops are very different from wild grasses. In modern wheat, the roots are much smaller than in wild grass. When the dust bowl came, all the wheat blew away. You are talked about living off of wild or semi-wild grasses, which will be a much, much lower caloric yield than the domesticated grains that we're used to. There's a reason agriculture only developed in the most fertile parts of the world. – Salmoncrusher Oct 13 '16 at 19:56
• modern crops are different. First cultivated ones wasn't. Of course was much less caloric, but still cultivating them was a winning strategy. – Mołot Oct 13 '16 at 21:09
• @Molot, In certain climates, yes. In other climates, it is not. Given the amount of labor required, and the need for grass to display wild-type characteristics, such as deep roots(meaning you cannot simply pull the crops out of the ground every year, dramatically increasing the labor of harvesting) not a viable strategy. Foraging for certain types of seeds from wild grasses as a supplementary food source, yes. Using wild grasses as your primary food source, no way. Early systematic agriculture was incredibly labor-intensive, and was only viable in a few very fertile areas of the world. – Salmoncrusher Oct 13 '16 at 21:28
• @Salmoncrusher Great catch. ricepedia.org/culture/history-of-rice-cultivation archaeology.about.com/od/domestications/qt/wheat.htm – Platypus Oct 13 '16 at 22:17

There are some theories that beer was a driving force in the development of agriculture. Hunting and gathering is actually a fairly efficient method of feeding a small group. Making large quantities of beer, however, requires a larger infrastructure. Change your intelligent species so that fermented fruits and grains are poisonous instead of intoxicating, and you remove one incentive for large-group agriculture.

Another change you could make to your species would be to make them more solitary than humans are. Perhaps small groups are fine, but larger groups start triggering territorial reflexes that may no longer results in fights to the death, but do make everyone anxious and uncomfortable.

At first glance, it seems that if things grow at all, humans can make desirable things grow in convenient locations and help the crops thrive.

What agriculture causes is a shift from wanderers to a fixed location for long-term year-round working of the land.

To break that, what occurs to me is to force the people to not stay in one place. Maybe the place where things grow changes from year to year, and other life has to follow that.

Maybe all attempts at proto-agriculture have led to disaster: blight or other plant disease wipes out the population. Going fallow after a year and spreading seeds far away is an adaptation to cope with the advanced diseases, fungi, and parasites that infest the useful plants.

Hunter-gatherers already have some advantages over agriculture -- in fertile areas, they need less work to produce the same amount of food. Agriculture's advantages are that it allows food to be stored to get you through seasonal or meteorological fluctuations in the availability of food, and it needs less land. So if your planet has a stable predictable climate with an all-year growing season (like the tropics on Earth, outside hurricane areas) and is sparsely populated, there's no particular advantage to agriculture.

• Even if I have all year growing season,say with axial tilt 0 degrees & circular orbit Agriculture improves yields per area, the band/tribe that starts doing agriculture will grow in numbers and beat the others. They could start with small improvements and become full farmers within some generations. – Platypus Oct 14 '16 at 12:49

You could have a plant limiting parasite or insect.

e.g. you have a "plague" beetle, it's larval form is something akin to an earth worm, and is essential for soil health (lets say there are no earth worms, just these guys).

When the plant population in an area reaches a given density the larvae pupate and emerge as ravenous stinging beetles that feed and reproduce in 24/48 hours, stripping plants/trees/slow moving animals & seeding the - now bare - soil with more larvae.

This provides a continent (or a an entire world) with self limiting flora.

The entire concept of farming goes out the window, by growing high density of crops you're begging for a plague of biting stinging insects that will eat your crops (and you, if you're not fast enough).

All ruminants roam looking for food, people follow the animals to eat them and find fruit, berries & grains to eat.

You could even have the insects also have timed breakouts, like Prime number Cicada's, people know when this will happen and retreat to mountain caves or up above the snow line to avoid them, possibly driving some herd animals ahead of them. The years following a breakout will be especially lean, and people have to cope with, or plan for that.

# Disease

On Earth it is a good idea to rotate crops to as disease can easily spread from crops of the same type. Plant based diseases on the planet could have evolved some trick that makes them much more virulent than on Earth. The plant population's defence is its incredible diversity, as only rare plants can survive. Planting an organised crop of of any type would be a bad idea, even for a single season. Using fertiliser also wouldn't help much, as more plants also means more disease.

Because farming techniques don't help plants, the population relies on gathering the naturally diverse native plants.

Animal farms are also rare. Disease makes plants somewhat sparse and unpredictable, so animals need to move freely to where their food is available.

One answer not suggested so far would be to not have the humans be the apex lifeform. If you had something big (dragons, demons, aliens, sky whales, or anything else you like) that was capable of crushing human settlements and devouring all their crops/herds then you would be forced to keep spread out and nomadic.

Any fixed habitation and certainly any fixed farming is just going to become an all-you-can-eat buffet for the apex lifeform.

This does have a big advantage over the other suggestions that you can have a fertile planet with plenty of life. You also get plenty of potential plot interactions with the apex lifeform.

• I think the tag reality-check excludes such creatures. For any non magical creature smart apes will find a way to beat see this great answer about megalodon worldbuilding.stackexchange.com/a/27096/26533 . On the other hand even we with all our technological progress can't beat the planet, if there's no rain on arid soil your crops die. – Platypus Oct 14 '16 at 12:08
• That's a fair point, and it's quite possible that techniques would be developed to hunt these apex lifeforms and eventually the apes would take over. However if the creatures were strong enough and dangerous enough then for a very long time the humans would not be apex. For example imagine a stone age tribe vs a pack of tyrannosaurus rex. They would avoid that, not hunt it. – Tim B Oct 14 '16 at 12:25
• At the beginnig maybe, but they will learn to hunt it. Traps and fire work on any animal quora.com/… – Platypus Oct 14 '16 at 12:57

This is rather easy if you rephrase the question slightly - Instead of making the "planet" unsuitable for agriculture, make the "plants" unsuitable for agriculture. Basically, you take away the calorie dense plants that humans are able to use for crops and you're all set.

To elaborate, a scenario can be that it takes 80 years (highly exaggerated) for corn to be harvestable, now no society is going to start growing it for food.

In addition to the above example, there are potentially limitless ways to do this. There can be really tall overshadowing (or nutrient sucking) trees that have not allowed grasses like wheat and barley to ever develop. Humans can't eat those trees but human's prey do. Or that nitrogen or some essential nutrient required by crops is just not there in sufficient quantities for mass cultivation. Or that the processing required for making the crops edible is cost prohibitive. Or that the viability of seeds is too low. Or even simply that there are just no crops around that are calorie dense enough.

The best part about this solution is that you don't have to change people in any way. They can be omnivores just like us but if there're no grains that allow mass cultivation then there is just no way to have a sustainable agriculture system.

Yes and no. You could make a planet where nothing could grow, but still have a suitable atmosphere for humans. For example, the ground might be rocky or icy, or there might not be enough sunlight for photosynthesis on half of the planet, and the other side is too hot.

But, even with that, you could not stop inhabitants from getting creative. For example, you could build a green house, and then import top soil and seeds and water, and then be able to grow plants. Your only limit would be how much of the necessary material you could import from other planets or manufacture. For example, humans can create their own fertilizer and exhale CO2 that plants need. So you'd just need the seeds, water and a suitable atmosphere (or greenhouse with suitable atmosphere).

Basically, if humans or humanoids can live there, other stuff, including plants, could grow there, with a little ingenuity and resources.

You could, of course, make a terrain that makes agriculture extremely hard, but you couldn't make it impossible.

Limit the food source to animals that must migrate, to limit the ability to pen them up. The animal's ecosystem in a medium that the hunters can't control, so you can't put them in pens or herd them. Steelhead that must spend years in salt water and return to fresh water for breeding is a real-world example. Alternatively, there may be an airborne animal that is edible, but moves around and again can't be penned/herded. This animal does not travel in large enough groups to collect a year's worth of food.

Assume toxic minerals in the soil taken up by plants and other animals. Your food source may be able to sequester them in one organ that the hunters can take out and then the rest is safe.

Now hunters have to collect what they can and preserve it, then travel to the next area where the food animal will be available.

[S]ome sources would be better then the other. Nothing prevents them to help the better sources to become more abundant. Sooner or later domestication will happen.

This is not how populations shift from gatherers to domesticating plants as a main food strategy.

Not every plant can be domesticated, not every environment allows for plant domestication, and there have been many regions throughout history that were simply not appropriate for developing plant domestication no matter how much people enjoyed eating the tasty foods there.

There are multiple scientific fields of study concerned with this very topic, but a very basic answer is that agriculture will never be more attractive then gathering until it absolutely needs to be (life is a whole lot easier when you don't have to work to grow your food), and even then it can't be done everywhere to just any kind of plant. Domestication doesn't simply just happen.

Natural phenomena (like hurricanes, storms etc.) could prevent people from spending time on agriculture, because the results of many months of hard work could vanish in a moment.