I understand, of course, that humans evolved for this exact environment! However, if you could travel back in time 2,000 years and modify our species (without any unintended health consequences), could you prevent the widespread environmental damage we currently do?

And could you do that without adjusting our psychology?

I'm looking for high-tech body modifications (not just 'turn us into bison') that would eliminate, or at least minimize, our inclination to drive down the road toward environmental degradation. That is, how would you build 'greener' humans?

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    $\begingroup$ The terms in this question are ill defined. "greener" and "environmental degradation" do not have clear meanings, certainly they are not objective terms. $\endgroup$ – BevynQ Aug 27 at 1:56
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    $\begingroup$ @DanePilot You do realise that someone from 2000 years in the future read your question and is doing what you wrote, right now? $\endgroup$ – Nahshon paz Aug 27 at 10:14
  • $\begingroup$ Seems simple enough— make us all highly allergic to the most potent environmental pollutants: methane, nitrous oxide, ozone, CFCs, HCFCs/HFCs. You'd have to leave CO2 as-is though, since Earth has a fair amount of CO2 naturally, and we'd be stay away from the technology of fire if people died whenever near even a small campfire. $\endgroup$ – Slipp D. Thompson Aug 27 at 11:57
  • $\begingroup$ The only thing comes to mind is LESS FERTILE. Because you know, fewer humans less environmental damage $\endgroup$ – jean Aug 27 at 13:16
  • $\begingroup$ You assume we are suited for this environment, but as we have a circadian bodyclock that cycles round longer than 24hrs , I'm not so sure.... :-) I wonder if there is a nearby planet with a 24hr 11min day? $\endgroup$ – gbjbaanb Aug 27 at 15:18

14 Answers 14


Make us become less fertile as conditions change...except we already do that.

Slowing down the human reproduction rate overall will not work - The cause of the human reproductive boom is not our high reproductive rate (we have one of the lowest reproductive rates of any species in the world) but our reduced death rate. Population growth without limitation is exponential; no matter how slow this exponent is, at some point it will skyrocket. Like Thanos's stupid plan, reducing human reproductive rate is a temporary solution at best; at some point we will exceed the carrying capacity of the planet anyway...

Unless we are able to detect changes in our environment and slow down our own reproductive rate when our population outstrips the carrying capacity of our environment. Many animals do just this, especially large predators like bears (which is why pandas are having so much trouble reproducing in captivity). However, these animals tend to become less fertile as food becomes scarce. The problem with doing this to humans is that we are so good at keeping ourselves fed that many are unlikely to notice the change until it is already too late. What humans really need is to become less fertile as life becomes easier.

Which we already do.

Population growth in developed countries is leveling off and in some cases (like Japan and Germany) has already started to decline. Because of this, most modern scientists agree that overpopulation is not a danger to the planet. As long as countries continue to develop, eventually the global population should stabilize with an average of 2 children per couple. Population growth will stop.

The real problem is not the number of humans, but the behavior of humans. A global measurement of human population growth vs environmental impact gives a skewed picture, because the population growth and environmental impact are not happening in the same places. Developing countries have the highest population growth, but the smallest environmental impact. Developed countries have the smallest population growth, but the highest environmental impact. It is that latter that must be targeted to inhibit environmental damage, not the former.

Directly or indirectly, you will need to modify behaviors

In prehistoric times, there were periods of plenty and periods of famine. In order to survive, humans would stock up during the periods of plenty in order to survive the periods of famine. The problem is that even when in a comfortable environment, the human body wants to consume as much as possible in preparation for the lean times ahead. In modern times, however, those lean times never come (unless our unrestrained consumption causes them to come).

So how can we fix this without modifying psychology directly?

One of the biggest sources of environmental damage occurs due to heavy meat consumption. The human body craves high-energy food, and given the option (which we have now, while we didn't in the past) will eat as much of it as possible. Land clearing for livestock, emissions and runoff from farmland cause immense amounts of environmental damage.

We already limit our own reproduction when conditions are too easy. If there was a way of connecting the drive to eat meat to this same part of the brain, such that developed countries were less inclined to eat meat, this would benefit the environment greatly. This can likely be done without significantly altering overall human psychology.

There are other changes that can be made to make humans less inclined to consume under comfortable conditions - like reducing the need for competition - but these will likely require more invasive psychological modification.

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    $\begingroup$ A modification so we don't find high energy foods as appetizing when we have a certain amount of body fat would help, less overeating, better for us and the environment. $\endgroup$ – John Aug 26 at 17:33
  • $\begingroup$ @John you could couple that to a old mating behaviour trait. if humans were slightly more picky about physical traits (think peacock) then its likely we would of evolved a more innate drive to look a certain way $\endgroup$ – J.Doe Aug 27 at 8:23
  • $\begingroup$ sure, developed countries have fewer kids, then they complain about "the ageing population" and demand more people (from developing countries) and the growth continues indefinitely. But even if the planet did end up with a stable 2-kids per couple, it'll only happen after weve overflowed the planet's capacity. $\endgroup$ – gbjbaanb Aug 27 at 15:15
  • $\begingroup$ @gbjbaanb you do realize most developed nations have stable population even with immigration, the US does not count because it is barely a developed nation when it comes to mortality. $\endgroup$ – John Aug 27 at 23:05
  • $\begingroup$ @John sorry but not a a chance, migration to most developed countries is very large - the UK for example has increased dramatically over the last 20 years, pop 58m grew to 67m, hardly stable. Richer EU countries the same, plus Aus NZ etc $\endgroup$ – gbjbaanb Aug 28 at 11:09

The damage we do to the environment is due to our decisions so you need us to be better decision makers.

Make the logical part of our brain a bit stronger and give us a stronger sense of humor.

Most of our problems stem from choosing instant gratification and ignoring long term problems. The logical part of our brain has to work hard to override instant emotional responses, often times just getting used to justify an emotional decision rather than actually making the decision. We are better at rationalizing then actual rational thought. If the logical part of our brain had an easier time overriding the emotional (not too easy we still screw up a lot) then we would be better at taking long term effects into account.

We are also suck at changing our mind. We tend to stick with the first thing we are told. One of the current ideas about what humor IS is that it is how the brain changes held beliefs. If a belief is provisional there is no issue we just toss it, but once we start integrating a belief we don't like to change it, the more ingrained the harder it is. Humor is believed to be how we change held beliefs, a mechanism that looks for internal conflict (combinations of logically inconsistent beliefs) and rewards the brain for challenging and changing them when they don't match. When two beliefs are too tightly held the conflict stops being funny and we get cognitive dissonance instead. We just ignore the problem and even get angry when attention is drawn to it. If humor reached a bit farther or cognitive dissonance was a little harder to trigger you would have humans who are more likely to change their mind when they see enough evidence instead of digging in their heels and denying the issue.

Will we still screw up, of course, You can't stop that and have an intelligent species. But at least we will be more likely to recognize problems and do something about it. You can't ask for much more than this since a lot of what we do is what any animals that can does, change its environment to better suit itself. Even with climate change most of the worry is about the impact it will have on us. So make humans better at seeking out and solving these problems.


OK everybody seem to be focusing on fertility. As good a point it is, and some answers and comments reflect that, the fertility solution alone has 2 major flaws:

  1. It is only temporary, you just delay the inevitable.
  2. it's already happening (as IndigoFenix pointed out). The problem is that we now live a lot longer than strictly necessary to infant and nurture the next generation.

I take it that all the answers towards fertility control have the tacit assumption that the underlying problem was overpopulation. So in light of that and of the point (2) above, my solution takes the problem from the other side:

Make us (much) less resilient.

At the moment we already have extremely resilient bodies compared to the whole range of biodiversity. We can survive in a wider range of temperature, pressure and gas composition, than most species (bar a few really impressive bacterias), so we can push the boundaries of our environment to a point which is 'uncomfortable' for us, but already deadly to many species.

If you make us more fragile, such that environment modifications puts us at a direct risk (not a risk over 10 generations) and force us to do a great deal of thinking and life choice in order to survive, I would count on the collective intelligence to find a few ways to live 'greener' in a stable lifestyle in order not to have to completely reorganise society everytime we dump a few tonnes of carbon in the atmostphere (and also avoid the inevitable massive death toll during the reorganisation).

This way, regardless of the actual human population level (prehistoric, current or future), the onus is on the humans to find a survivable way to handle it.

Hopefully the humans have the mental capacities to find workable solutions, the only thing they needed was an actual incentive*

*(as said above, this is dangerous for your grand-grand-grand children is not resonnating much with the current short term views of modern societies. But change now or die now might speak to more people, and the ones who don't listen will feed the ecosytem shortly anyway).

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    $\begingroup$ That will have exactly the opposite effect you want. Make humans less "resiliant" (whatever that means) and it will mean humans will do more to alter the environment in order to survive. $\endgroup$ – Keith Morrison Aug 26 at 15:00
  • $\begingroup$ @KeithMorrison ... regardless, if they are weaker they'll have to alter the environment until they find a good balance and not deviate much from there, or else ... the incentive to keep things balanced is still there. $\endgroup$ – Hoki Aug 26 at 15:18
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    $\begingroup$ To use one example, suppose humans were predated on by, say, bears. The result wouldn't be a lower human population living in balance with bears, it would be the extinction of bears. $\endgroup$ – Keith Morrison Aug 26 at 22:04
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    $\begingroup$ Then the opposite - make humans (much) more resilient to everything, faster, smarter, stronger all around, to the point that a group of bears living next to me is not perceived as a threat, no point in killing them for food (if hungry, I can just take a bite of this pine tree - no reason to farm, either), or for their pelts (can survive plus-minus 50C naked, no problem), no need for roads (can run everywhere I want with a speed of a race horse), no reason to... basically, any modification of the environment, because it's already kinda perfect. Until hordes of people chew down all the trees. $\endgroup$ – Headcrab Aug 27 at 7:03
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    $\begingroup$ One reason humanity expands with excess children is that we have lots as many are expected to die young. So making us more likely to survive childhood will see fewer kids born. $\endgroup$ – gbjbaanb Aug 27 at 15:17

Make us less fertile

There are a myriad of reasons why we as humans do what we do and changing a single one will make us less successful as it is that very resourcefulness that has allowed us to survive and circumvent every challenge thrown at us by the world so far. In point of fact, going back only 2000 years is leaving it far too late to make an evolutionary change to us other than fertility because a lot of what we were doing to the environment we were doing that far back. The difference between the Egyptians of old and we today isn't our approach; it's our numbers.

We are spreading across the planet in numbers that the planet could not sustain if it wasn't for our science, our ways of harnessing energy for transport of food and other supplies, etc. The problem with the environment today isn't a problem of our methods so much as it is of our rate of consumption. If we were to dial that back significantly, then the planet could handle it but the price would be that within a generation there would be far fewer of us. So, don't have as many of us in the first place.

If we did something to dial back fertility 2000 years ago so that even in ideal conditions, we couldn't expand in numbers at the rate we do, then we have made a great start on solving the problem. The issue as I see it is that we are the first species ever to be able to create our own ideal conditions, to adapt our environment to us rather than the other way around, so as a result we increase in numbers.

But, if there was an increased energy cost in birthing, say, so that the absolute maximum number of children a woman could bear in her lifetime was 3 (replacement for the parents and the occasional non-breeder or fatal accident) then we are greener by virtue of being fewer. We don't need the massive energy intensive infrastructure to move food and the like around the planet, and we end up living in balance with the environment, at least more so than we do with the numbers we currently have to support.

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    $\begingroup$ You'll have to beef up the immune system while you do it, or else those three kids per couple will become one and a half without modern medicine, and your population will decline. $\endgroup$ – Cadence Aug 26 at 1:33
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    $\begingroup$ @Cadence that's very true, but I'd also argue that occasional declines would not only be inevitable, but necessary to keep the population at sustainable levels. Also, naturally lower numbers, especially with a lower overall population density, would reduce the efficacy of most contagious illnesses due to lack of the transmission opportunities that modern diseases enjoy. Still, it's a valid point you raise. $\endgroup$ – Tim B II Aug 26 at 1:37
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    $\begingroup$ Not sure that helps. For much of human history there was a physical "bottle neck" to reproduction (babies heads diameter vs ahem) that affected fertility. We literally side stepped the issue using C-Sections. $\endgroup$ – Aron Aug 26 at 10:23
  • $\begingroup$ Population growth is exponential. If that exponent is greater than 1, population will still skyrocket at some point. You've slowed the growth rate, meaning the world doesn't become quite so crowded quite so fast, but the end result is the same - exponential growth of the population to unsustainable levels. If the fertility rate is still above replacement levels, you've just delayed overpopulation, but have done nothing to prevent it. $\endgroup$ – Nuclear Wang Aug 26 at 14:13
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    $\begingroup$ @Aron no we really didn't, population growth SLOWED after the invention of the C-section. If your children are more likely to live humans start having fewer children. In countries with good healthcare population growth is negative. $\endgroup$ – John Aug 26 at 18:00

Gather in close, wise children, sit here in the cool shade and learn more about the Olde Times of the Barren Lands. Listen to our revered New Ranger visiting our Forest today. Listen and learn.

There's legends told of our ancestors, the Sun Walkers, who, before the great Change, traveled freely without covers upon the bare surface of Earth's lands and seas. These were the Sun Walkers who worried not if the Sun danced upon their bare skin; who worried not if a young one chased a butterfly out of the cherished Deep Canopy into the dangerous sun-dappled Borderlands; who worried not about careful Elder Tree care and New Forest regrowth planning. Indeed, these short-sighted Sun Walkers actively practiced sacrilegious clear cutting of acre after acre of our protective Forest lands for many generations before the great Change.

The legends say in the ten years before the Change there came the First Forest New Ranger, the seer prophet with dire warnings to protect and restore what remained of the Forest lest their carefree way of life in the Light be forever changed to seeking the Dark. Warnings that went unheeded during all of the Last Sun Walker Decade. Warnings that heralded the coming of the Blister Plagues that took root amongst all the Sun Walker tribes and the coming of the Blister virus that even now lays hiding just under the skin, carefully awaiting its chance to burst forth for those unlucky enough to be caught unprepared in the Sunlight.

Those of you already laden with Blister scars... look closely at your scars and see in them the ravaged, barren, wrinkled deserts of the legendary Lands in the Sun. Remember the plight of the foolish Sun Walkers and remember to give thanks every day for our sacred Deep Canopy and for the work of our many New Rangers.

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    $\begingroup$ A very pretty little vignette, but does it address the question in any shape or form? :) I'd like to read the short story, though! $\endgroup$ – Chris the Hairy One Aug 27 at 9:01
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    $\begingroup$ @ChristheHairyOne I believe the idea is; make humans very sensitive to sunlight, such that they can only come out during the day if they live in a forest (or possibly New York City), thus ensuring they don't chop down all the trees. $\endgroup$ – Jontia Aug 27 at 12:47
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    $\begingroup$ @Jontia exactly the thought. The time traveler spends awhile working at conservation efforts then gives up and starts spreading the gmo virus he brought with him. How the virus works/what chemical processes it inhibits or exacerbates is author determined $\endgroup$ – N2ition Aug 27 at 22:38
  • $\begingroup$ TBH, I think you've justified the full burkha! ;) Or very large parasols. The fundamental problem is that humans are inventive and can (given time) devise a solution to most environmental problems and physical short-comings. $\endgroup$ – Chris the Hairy One Aug 28 at 11:02
  • $\begingroup$ @Christhehairyone I wondered the same- we're very good at adapting. If this is going towards a fictional work, it seemed believable that working the religion angle into it during the right time in the population growth could send the society as a whole in a more deep forest or jungle cover loving direction. Look how long some of our world religions have lasted. I also imagine the New people have figured out good ways to cross open lands and seas at long distances at night or in covered structures only $\endgroup$ – N2ition Aug 28 at 22:38

Here are two genetic modifications that could be considered.

  1. Gluten tolerance removed.
  2. Dairy tolerance removed.

The mutation that allows humanity to digest Wheat and Dairy allowed population growth to explode as agriculture was developed. Introducing additional intolerance to Corn and Rice may also be helpful.

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    $\begingroup$ So you want to encourage more meat production and more intensive farming? $\endgroup$ – John Aug 26 at 17:55
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    $\begingroup$ If we didn't have dairy and gluten tolerances, we'd end up cultivating something else - sorghum or millet for example. Oats are also gluten free, and very tasty when baked with butter and sugar. $\endgroup$ – gbjbaanb Aug 27 at 15:22

I think there is something important that must be understood : All species are modifying their environment through their behaviour. The widespread environmental damages that we do now is due historically to the order of magnitude of two exponential growth : first, in population and second in using energy and machines to augment our capabilities and make our lives easier, thus making a huge change in the environmental impact we have.

Regarding population, in western countries, the birth rate is below 2, which means that we are not on a long term growth. This part is already more or less managed, and the number of living people should be stable on the long term. No need to modify anything regarding population in my opinion.

The second exponential growth is the production / consumption we do. (2% per year of growth, over 200 years, it's already 50 times more).

However, as you might have noticed, we don't feel that more rich compared to our ancestors, because we compare ourselves to our neighbour and what seems "normal" is slowly changing in our minds. Similarly, we don't feel what the world was like 100 years ago. (That's called baseline shifting : what was considered a big fish was not the same for our grandparents compared to us, as well as what is a "hot summer" or a "cold winter", or a crowded area, or normal job conditions, etc...) This is what makes it difficult today both to :

  • Ask people to reduce their lifestyle (for them, it's "normal")
  • Make them understand the long-term impact we have. (for them, it's "normal")

Now that the problem is clearer, here are two positive solutions (in the sense it wouldn't hurt anybody's ethics). We can fix it either by :

  • Making people more rational (and interested in the long-term of the species, depending of how you see people nowadays), and thus, people would base their decisions taking the facts above into account more easily, because they'll know they are very lucky and the environment in great danger

  • Giving people a long-term memory (maybe coming genetically from their parents), so that they'll remember (more or less) how it felt a long time ago.


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Make humans unable to digest animal fat and protein.

Animal husbandry for meat and dairy production accounts for a lot of greenhouse gas emission and growing food for animals requires a lot more land than growing plants for human consumption. Going vegan allows to feed a lot more people per square km of farmland, which means we require less deforestation and less use of pesticides, herbicides and fertilizers.

Make humans more temperature resistant.

A lot of energy is used for heating in the winter and air conditioning in the summer. If humans could live comfortably in a much larger temperature range, then a lot of this energy could be saved.

Make humans able to see in the dark.

Another large contributor to energy usage is artificial light. If we wouldn't need it, we could save a lot of natural resources.

But in the end it won't do much.

If you don't considerably change the psychology of humans, then the human population will keep growing and will keep finding new ways to use Earth's resources to improve their comfort. So you will just delay the point at which humanity reaches the limit of Earth's resources.

  • $\begingroup$ Perhaps it could do much. There are different groups of peoples on Earth already now and through history that have very different psychologies and societal attitudes towards living both on and with the land and waters while practicing sustainability $\endgroup$ – N2ition Aug 28 at 22:44

By making us as a stronger alpha predator

Humans hunt in groups, cultivate lands, manipulate objects, even grow a bigger brains because we're not come from the top of the food chain.

If we can hunting solo whenever we want, the probability for us to resort to using sharp objects and fire will be lower. We won't need to develop hierarchical organization, we will be just enjoying life and roam the forest to this day.


I agree with Tim B. Fertility is humanities downfall. We form communities, it is in our blood.

https://socialmediaweek.org/blog/2015/01/5-key-reasons-people-join-communities/ A great blog that goes more in-depth here.

As the communities grow through pair bonding, each area expands exponentially. Seeing that you do not want any psychological tampering, making pregnancies rarer would, theoretically, do the trick.

  • $\begingroup$ Unless your birth rate is at exactly the replacement rate, the population is still going to grow exponentially. You've slowed overpopulation, but haven't stopped it. $\endgroup$ – Nuclear Wang Aug 26 at 14:17

Taking up IndigoFenix' point, probably the most useful mod would be to re-engineer the gut to digest cellulose and not animal proteins (not sure that this is chemically feasible, though).

Ultimately, it's all doomed to fail. Unless you have a way of winnowing the population on a constant basis, it will eventually creep up to the point that feeding us all damages the environment in a catastrophic way. Those who say we should limit reproduction are missing the point - it's not our reproductive capacity that has caused our population to burgeon, but our adaptability. We can, and have, adapted to every environment on the earth (and off it!) but these days we do it mostly through the application of technology.

If you want to save the planet by tinkering with humans, the best thing to do would be to make us no smarter than the rest of the animals.

  • $\begingroup$ except population growth in humans stops once mortality is low enough. Winnowing the population makes the problem worse not better. $\endgroup$ – John Aug 26 at 17:57
  • $\begingroup$ I don't agree with your postulation. I do agree that, currently, 'developed' nations' population growth slows or even turns negative, but that is an unconscious cost/benefit analysis on the part of potential parents. If resources were easier to come by i.e. no scarcity due to overpopulation, then I submit that the population would continue to grow. $\endgroup$ – Chris the Hairy One Aug 27 at 9:08
  • $\begingroup$ Of course it is unconscious, it is response to how likely a child is to survive, when child mortality is high R strategy is better, when mortality is low many animals humans included move towards K strategy, higher investment in individual offspring and having fewer offspring. High investment is less productive when their is a good chance said child will not survive. Resource availability is not a factor otherwise most developed nations populations would be growing not shrinking. $\endgroup$ – John Aug 27 at 22:50
  • $\begingroup$ you see big population booms right when mortality starts dropping since the behavior change is not instantaneous. It may even require crowding to trigger. $\endgroup$ – John Aug 27 at 22:53

As most of the other answers are focused on population control as a solution, let's take a more proactive approach, seeding our genome with a few time bombs. Have your time travelling geneticists encode a few pandemic capable viruses with high lethality into the junk sections of our DNA and then set up triggers to release them when needed. If each plague is triggered by a different indicator of environmental decline (famine, drought, pollution, radiation,...), then every time we start to mess things up, along would come a plague to slap us back down and teach us humility.

  • $\begingroup$ Spanish Flu and Bubonic plague would like to say "been there, done that". Poor farming practices and hygience due to overpopulation will undoubtedly see such pandemics (eg Avian Flu) kill loads of us like they did back in the past. $\endgroup$ – gbjbaanb Aug 27 at 15:25
  • $\begingroup$ @gbjbaanb, yes but if there were more plagues hidden in our junk DNA and if we encoded triggers such that each plaque becomes active only in the presence of the specific environmentally destructive behaviors which we are trying to filter out of our subsequent history, the plagues might collectively say "here again! stop doing that!" $\endgroup$ – Henry Taylor Aug 27 at 15:40

Give us a better sense of smell.

(I'm cribbing from Larry Niven's There's a Wolf in My Time Machine here, of course.)

If we can't tolerate the smell of coal smoke, or of petroleum, the industrial revolution is going to wind up as a non-starter. That eliminates the more severe environmental risks our current civilization faces.

... which isn't to say the resulting hypothetical civilization might not come up with some new ones. But at least they'd be different ...

  • $\begingroup$ Actually we did a lot pf damage through deforestation and hunting long before industrialization begun. $\endgroup$ – John Aug 27 at 22:54
  • $\begingroup$ @John, not I think on the scale the OP is talking about. Or at least that was my interpretation of the question. $\endgroup$ – Harry Johnston Aug 27 at 23:31

Self-regulating fertility

Make humans break down if they live in too cramped quarters.
Increase this to a degree that even Rome could not have existed.

There are side effects, however.
First, humanity disperses into smaller villages, towns get depopulated because people just cannot stand being in those crowds anymore.
Second, those smaller communities are less resilient to attack. The loss of life and commodities means that there will be less surplus for luxury activities, in particular focussed research. So... expect the Industrial Revolution to happen much later, or maybe not at all.
Third, humanity will still grow and fill the world. It will not be as concentrated, but ultimately, its global ecological footprint will exceed sustainability. It will just happen later. (This is a potential plotpoint: Avoid ecological disaster, just to see a different disaster looming at the horizon.)
Fourth, evolution will work against you. People will live in overly large communities anyway (just because the advantages are so large). They will suffer, they will die, but they will still come, just because suffering in a city is slightly less horrible than dieing in yet another raid. Which means you have a breeding ground (literally!) for people where your mutations are reverted.

One thing to combat this evolution is to get the raids under control.
Historically, raiders got eliminated once police forces could communicate faster than raiders could move - i.e. with the invention of the semaphore.
So... if your hypothetical benefactor forces humanity into dispersion, he should consider giving them that idea. A semaphore is not terribly difficult to build, it is mostly about being dedicated enough to work out the tricky optimizations and improvements.
The other disadvantage of dispersal is that intermediate products will have to be carried over longer distances. It will shift economic advantages, but I do not think that it will eliminate technological progress (of course, I may be wrong).

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    $\begingroup$ humans already break down if they live in too cramped of conditions, it is called disease. And a high death rate just encourages having more offspring because more are dying. This is why population growth drops once infant mortality becomes rare enough. Many children stops being an advantage when most of them live. $\endgroup$ – John Aug 26 at 17:54
  • $\begingroup$ Humans do not break down from an evolutionary point of view: they still reproduce. $\endgroup$ – toolforger Aug 27 at 8:34
  • $\begingroup$ Dead humans do no reproduce. $\endgroup$ – John Aug 27 at 22:57

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