Here's a thought experiment I've been pondering for a while:

  1. Make a copy of Earth as it existed 5000-ish years ago, with all of the plants and animals, but without any people or any traces of human activity
  2. Populate it with 50 adult humans (volunteers?) - 25 men and 25 women. Assume they are all 20 to 30 years old, fertile, reasonably fit and healthy, and have average intelligence and a high-school level education. They start with absolutely nothing - not even clothing - but they bring all of their 21st century knowledge. That is, no books or encyclopedias - only what they can recall from memory. They will have to cope with the weather and elements, and with potential conflicts with wild animals. Basically they have to rebuild the human race. Oh, and they all start out with a common language.

What would happen? I imagine that, if they are determined, they could reach a 17th century level of development fairly quickly - within a generation or two. What would happen after that? Would their track parallel "real" human development, or would they go off in a completely different direction? What if you were one of the 50? Would you advocate sticking together, or venturing out? What else could we speculate about?

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    $\begingroup$ What kind of skills do they have? Surviving is going to be a challenge. Two people have trouble surviving in the wilderness. What will they eat? When's winter? How will they store food for it? Fifty would have low genetic diversity and little room for early fatalities. I count six questions in your final paragraph. Please think about where to start asking and reduce down to one question. As is, this is rather broad. $\endgroup$
    – Brythan
    Sep 12, 2016 at 23:03
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    $\begingroup$ I was intentionally broad and vague because the aim is to stimulate discussion rather than answer a specific question. Assume an average skill level, however you define that. However, if they are all volunteers who know what they are getting into, it's likely that such a project would draw people from the higher end of the curve. $\endgroup$ Sep 12, 2016 at 23:30
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    $\begingroup$ Yeah, decreasing scope would be nice. I started to try to write an answer, but the reasons they would never make it to the 17th century got so numerous that it started to get depressing. If we decrease scope, we can focus on just one or two reasons they wont make it. $\endgroup$
    – Cort Ammon
    Sep 12, 2016 at 23:31
  • $\begingroup$ "What else..." is an inherently too-broad question. You're basically asking us to write part of your question for you. $\endgroup$
    – Frostfyre
    Sep 16, 2016 at 11:16

4 Answers 4


I don't have a full answer, but I suspect having only 50 people will cause problems with reproduction. This will lead to in-breeding and a population that isn't genetically diverse enough to survive climate shifts, and will eventually lead to a population of people with health issues from genetic diseases. Human population may have once dropped to as low as 2000 people, so a lot of genetic diversity was lost and the species still made a comeback, but I don't think 50 individuals will be enough. I hope someone who knows genetics comes by to weigh in on this.

My guess is that they won't live long enough to advance a technological level, especially because technology can only really be pursued by people who have their basic needs taken care of (water, shelter, food, etc). With that small a population and no traces of pre-built human infrastructure to take advantage of, they'll be too busy fighting for survival to pursue technological development, and unable to produce a viable population capable of building on anything they do manage to create.

TLDR; I'm pretty sure they're doomed.

  • $\begingroup$ I'm not sure I buy that. Admittedly I'm no expert in genetics, but there are several isolated populations on Earth today (mostly in the Amazon region and in Papua New Guinea) who have persisted to the present day with very small populations and little or no outside contact with other people. $\endgroup$ Sep 12, 2016 at 23:37
  • $\begingroup$ @CharlesBurge Fair point. Although, I still stand by my second paragraph, that they'd be too busy trying to survive with such little manpower to pursue academic/technological goals. $\endgroup$
    – Cody
    Sep 12, 2016 at 23:54
  • $\begingroup$ It'll be many generations before any problem with genetics turns up, if at all, some species have survived with 20 individuals. en.wikipedia.org/wiki/Northern_elephant_seal $\endgroup$
    – Karl
    Sep 13, 2016 at 0:30
  • $\begingroup$ They don't mate like us. Depending on where you search yes you can find something like North America was settled by as little as 70 people but the gene pool will be very limited. Most research said something like 160 people will be optimal minimum to have a healthy population in the long run. And for the seal "Nevertheless, a genetic bottleneck exists in the existing population, which could make it more susceptible to disease and pollution." $\endgroup$
    Sep 13, 2016 at 12:14

This kind of question has been explored several times, in varying degrees. Usually there's some sort of crib to make it more plausable, like a single computer with every book ever written on it, or something like that. Some of them even offer free resources lying around on the ground.

This question has none of that, which makes it easier. The probability of reaching 17th century development in one or two generations is nil. This sort of though experiment shows one key reality: knowledge is not everything. It doesn't matter if you know that you can burn coal for fuel, you still have to go mine the stuff by hand, and you need to have a pick-axe to do that!

Without any modern medicine, life expectancy is going to be short. At best, your 20-30 year olds have about 20 years on their life. They're going to have to think about pumping out the next generation fast. As a father, let me tell you exactly how much spare time the next generation gives you to ponder things like building steam engines. And, of course, we need to teach the next generation, but we have no textbooks. How do you explain to the next generation the value of the things we learned in school when they have no value here. Algebra? Fat chance! Physics? Nah, though you will see the practical side of it.

Once all that knowledge is gone, you're now at least 20 centuries away from your goal. Not that it did much. Most of what we know is to survive in the modern world. Surviving in the wild is a completely different beast, and little to no synergy occurs between the two.


You have adults between 20 and 30 years old with only high-school level education. And they are volunteers. Sounds like you are selecting for people with a bad economic situation. Maybe people who has put some survival skills to use already?

Assuming they are on a good location that is with abundant trees at least moderate fauna, and a good source of water. And at safe distance from any notable predator... they could reach Neolithic in matter of days if not hours.

They would probably not get the metal ages as developing mining would be hard work with little reward. Instead they will focus on hunting and gathering. Perhaps for the second generation they will have farming.

They had some education, and they will be willing to pass it down. Yet, as Cort mentions in his answer they will skip a lot of "useless" stuff - that they probably don't remember from high-school (that was at least a decade ago for some of them).

Writing will probably be doing marks with charcoal or clay brick on stone or wood. Or they could start marking marks on wet clay if they are clever - or if they remember that class about the Sumerians in high-school - I don't think so.

And then be stuck there, indefinitely.

I'm guessing that to bootstrap the metal ages, they will probably have to figure out a furnace and get some iron from a meteorite. Get some tools that would allow actual mining.

They could get gunpowder without mining. Charcoal from burning wood, sulfur from a volcano... But saltpeter from manure or compost doesn’t seem something they would do if they don't know how to do it already, much less making nitric acid to make saltpeter from it (Edit: I don't know about making nitric acid without electricity).

Healthcare is trash in the colony, these people only have high-school level education... they don't have the education of the indigenous tribes that know what plants work as antibiotics, anti-inflammatory, analgesic, or poison. They will have to learn the hard way... and that requires time and death.

With bad healthcare comes bad life expectancy. Also there are no contraceptive methods! Besides what people need here are more hands at work. All points to families with lots of pregnancy. Oh, and high child mortality.

They would soon discover some alcoholic beverage made with local fruits - just some juice nobody drunk - and they will enjoy the booze. This will probably be for the best because - if they are not boiling water – then water has more bacteria in it. Also, I'm hoping they don't mix their poop with the water supply, or they will be doomed.

Other than that, they will be ok. Still, nowhere near the 17th Century, more like somewhere between 25th Century BC and 22nd Century BC.

I don't think they will follow the same path as the humanity did, they will do a few early leaps. And there is a strong chance that they will not create vastly diverse religions. Furthermore the government will either resemble a democracy or go for a monarchy.


It's worth exploring what 5,000 years of evolution would do in a planet where humans aren't there to be the top of the food chain (and hunting all other threatening animals to a safe level).

These 50 humans, regardless of their training and knowledge will be thrust into a world where some other animal species will have evolved a lot in terms of killing power and intelligence. Dinosaurs got to a pretty healthy size and appetite before they were made extinct.

Basically, it's going to be a lot like "Aliens vs Predator". Humans will have to survive, reproduce, thrive while being hunted by some pretty mean animals.

They're going to need a bigger boat.


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