I knew a professor that loved getting freshmen classes because he could disabuse them their Yankee in king Arthur's court ideas about how easy it'd be to bring technology back to the past. He had a whole slew of experiments that would explore path dependence and the difficulties of creating technologies with the available resources. Nominally this was to help them not underestimate the intelligence of early humans, but I think he enjoyed it.

These things are easier if you have an idea ahead of time of what you're making, but that has to work in a cultural context and that still doesn't mean they're easy. For instance, how would you would you build a useful saw out of stone? Can you recognize the wild ancestors of wheat and convince someone to keep at the process of domestication for thousands of years?

It's likely that ancient humans were adept at many of these things, like salt preservation, warm clothing, contraception, spun fibers, and boats. Many of the others (agriculture, wheels, etc) simply wouldn't make sense outside their native cultural contexts.

In the meantime, you'd probably have to learn from them the basics of survival.

I feel like the pendulum has swing too far in the other direction on this topic, actually. Yes people in the past weren't dumb, and shouldn't be under-estimated, but even a normal person could provide huge gains to any pre-modern society. Their understanding of mathematics, biology, evolution, medicine, astronomy, economics, reading+writing, organization, etc. are immeasurably valuable. I don't think people appreciate how much "ideas" are, in some sense, a kind of technology in themselves. Yes you probably couldn't make yourself a queen of the land with your advanced knowledge, but you could massively improve this society in fundamental ways. Like get infected with cowpox if you want to get vaccinated (a term meaning of or from cows btw!) against small pox.

>It's likely that ancient humans were adept at many of these things, like salt preservation, warm clothing, contraception, spun fibers, and boats. Many of the others (agriculture, wheels, etc) simply wouldn't make sense outside their native cultural contexts.

For people this primitive, even elementary metalworking would be revolutionary. Yes you'd have to do a bit of tinkering to work out the kinks, but iron ore pre-modern-extraction was everywhere, and once you have the foreknowledge that heat special rock -> smash into shape -> better-than-rock tool it's not hard to figure your way to something groundbreaking.

I do think you'd be limited in how much you could change things by how far back you go, but mostly due to human life span. The more new technologies you need to personally 'invent' the longer this stuff takes, as you'd need to experiment with on-the-ground resources and techniques until you can successfully realize your conceptual understanding. I know what a blast furnace is, and because I have the key concepts I can eventually build one with some trial and error. But it would take years if I had to start from just sticks and sand.

> Their understanding of mathematics, biology, evolution, medicine, astronomy, economics, reading+writing, organization, etc. are immeasurably valuable.

You could tell them that disease is caused by tiny animals, and that the earth is a sphere that orbits the sun, but getting them to believe you is a another thing. And making use of it yet another. You won't introduce quarantine just because of germ theory: book of Leviticus already has a version of quarantine, "the law of the plague" well before germ theory.

> You could tell them that disease is caused by tiny animals, and that the earth is a sphere that orbits the sun, but getting them to believe you is a another thing.

I can find a cholera outbreak, and tell whoever will listen to stop drinking water from the local wells and eating from the local markets. Go to another part of the city for water and food. Those who listen, even if only one, will be my proof. I can also do a cool science experiment with seaweed agar, silver and bacterial growth but that's not as dramatic.

The earth being a sphere that orbits the sun can't be proved without a telescope, but I can propose a vastly simpler and just as accurate approach using kepler's laws. If I was paying attention in high school physics, I can even do cool stuff with Newton's laws of gravitation to show that "As above, so below" (the planets obey the same law of gravity that we earthlings do).

Yes people might still not believe you, as we can be a stubborn and prideful species, but you know the 'why' of many things and so can keep making correct predictions based on that.

> You won't introduce quarantine just because of germ theory: book of Leviticus already has a version of quarantine, "the law of the plague" well before germ theory.

The bible simply lists procedures, it doesn't explain why you do these things or allow you to extrapolate to other situations and scenarios. By contrast, simply by knowing the "why" of infectious diseases, a smart person or government could isolate the cause of - for example - the black death fairly rapidly (rats w/ fleas) and begin taking steps to solve the issue.

A modern person has a head full of correct answers for questions people 2,3,4000 years ago have yet to even ask. That's powerful stuff, and once they've proved their credentials in some way the books they write will advance humanity by millenia.

> I can find a cholera outbreak, and tell whoever will listen to stop drinking water from the local wells ... Those who listen, even if only one, will be my proof.

Results with diseases have a fair amount of chance, as we should all know by now. It might go as you say, it might not. Your disciple might leave and get cholera soon after due to exposure beforehand. A person who stayed and didn't get cholera might attribute their success to the manner in which they prayed. Or your guy's success to the manner in which they prayed.

It's hard to falsify the assertion that "they were not stricken because they were righteous / said the correct prayer", and "statistical significance" is not a dramatic or obvious thing to convey.

I don't think they'd remember the tips about smallpox, considering it hadn't evolved yet. As for iron smelting, we have a wealth of experimental archaeology on the subject under much easier constraints than you're proposing. The DARCs team [1] took 4 years to figure out a usable bloomery based on archaeologically known designs and years of prior experience, and it took a decade more to get all the modern materials out of the design. You could certainly cold-work iron if you could identify the right meteors, but those are rare and notoriously difficult to find [2].

All I'm saying is that you're vastly underestimating the knowledge, skill, and cultural context that went into these technologies.

[1] http://www.warehamforge.ca/ironsmelting/

[2] https://sites.wustl.edu/meteoritesite/items/some-meteorite-r...

One wonders if the concept of language 70kya was sufficiently advanced for you to transmit ideas beyond the immediate and concrete. I wouldn’t be surprised if you’d have better luck with water wheels than animal domestication, despite the latter preceding the former.

I've sometimes wondered about this as well. We can all understand how saws work; but can you actually make one from scratch? How about a rope? Do you know where to find the right kind of fibre, how to correctly process it, and then make it in to a functional rope? Do you have the know-how to functionally domesticate wild animals and cultivate crops?

I'd consider myself a pretty handy guy, but if I were whisked away to 70k years ago this very minute then I'd probably struggle with a lot of that, even though I roughly know how to do it. And that is ignore the obvious communication barriers, that you also need to spend time on basic survival, and things like that. A lot of these crafts developed over generations partly because while the concepts aren't all that complex, the actual doing of it in a way that's effective is a lot harder.

I certainly think it'll take a lot more than "days or weeks".

Primitive saw is just a rope + sand + water.

The problem was not to make things, ancients were able to produce few very advanced tools, mechanisms, and technologies, but to save them and pass knowledge of making them to future generations.

To make a dent, you will need a tool for mass spreading of knowledge en masse: a church, a library, a copier, or a book making machine.

> peak physical condition

A lot of our ancestors where not in a particularly good physical condition because of how horrible their nutrition is.

Look at prisons with bad nutrition and you’ll notice a large amount of people with some serious muscle mass. If you’re getting regular, very intense exercise (as you would need to as a hunter-gatherer) you’re in the top x% of the world population by fitness, no matter if you’re slightly nutrient deficient. Furthermore, we have at least some reason to believe that prehistoric populations weren’t so badly fed that it led to physical issues - they regularly reached heights equaling that of humans in recent years, far taller than the poorly fed people in e.x. medieval Europe.

Furthermore, modern humans have plenty of disease and issues caused by our modern environment that would render us far weaker 70 kya. Near/farsightedness, teeth issues, diabetes, obesity, repetitive stress injuries, etc. are entirely modern issues. Then look at the comforts we’ve gotten used to (shoes, clothing, soap, a too-clean environment for our immune system etc) - and I have no doubt that a modern human would be in far, far worse shape for the prehistoric life than your average person 70 kya.

Prisons with low calories nutrition have weak thin people in them. Muscles don't grow of you don't eat protein and sacharids - no matter how much you exercise.

You can have sucky nutrition for lack of vitamins etc and those will eventually leave you in bad physical condition. Even if you gain muscle mass temporary, damage to health will be real.

Hunter gathrer also don't have reason to bulk up unlike those prison guys.

Interesting thought experiment. Language/communication barrier and that whole getting murdered for looking different aside...if you were able to accomplish such things, I'd imagine the world you came back to -today- would look much, much different.

> - "Water bottles": animal skins sealed with pitch

Where would you get pitch? Isn't it only found in a very few locations?

You can make pitch by burning certain woods like pine and collecting the stuff that drips from the fire. Also, maybe I’ve been particularly lucky, but I’ve found bituminous deposits in the wild before that would probably be usable. Barring that, tree sap or beeswax would also be very useful for sealing.

Please teach them how to make durable records!