Hacker News Reader

> Then someone will give that mee Iron sword/knife/axe a try , duel a friend, ruin their bronze weapon, and said friend will be like "holy shit I want an iron sword too it's way too good" and bam you got a meme.

Iron is not a superior material to bronze, if anything it's inferior. Iron's either soft or brittle, depending on carbon content, neither of them awesome qualities in a tool or a weapon. Also, iron's considerably more difficult to smelt, and fully melting iron was not possible at the temperatures achievable with Bronze Age technology. Even after you learned that you need to use charcoal and very high temperatures to reduce iron ore, what you got was a spongy mass of very impure iron at the bottom of your furnace that you then had to refine further.

The biggest thing that iron had going for it was logistics. Where there was copper, there was no tin, and vice versa. Sourcing tin required trade routes thousands of kilometers long – no doubt the demand for tin was a large boon to long-distance trade across Europe and Asia, but it made bronze an expensive commodity.

It required new furnace technologies and a millennium worth of experimentation to perfect the art of controlling the carbon content (and what we now know is the crystal structure) of iron-carbon alloys precisely enough to make steel, and in particular steel blades that combine a hard (martensitic) edge and a flexible (austenitic) spine.

(For the record, Dwarf Fortress (unsurprisingly) is one of the few games that get this mostly right.)

One big advantage of iron is that you can forge it. Bronze has to be cast or cold worked (with annealing steps as necessary). You can't forge weld bronze either, so you need to braze/solder parts together. A skilled blacksmith can forge things from iron quickly and with little waste. It's especially important for things like nails and arrowheads that are needed in mass quantities.

Good point!

Very minor semantic nitpick as a metallurgist, martensitic and austenitic are not terms that distinguish the ductility of the metal, they are ways the atoms organize into crystal structures (which do have an effect on hardness/ductility).

Austenite is one of the high temperature crystal structures of iron, and is not usually seen at room temperature except in certain non-heat-treatable stainless steels, and in highly alloyed steels some small amounts of retained austenite remains that doesn't get the chance to transform due to low cooling rates and suppressed M_f temperatures. Martensite forms by rapidly cooling austenite without giving the atoms the ability to re-organize into their preferred structure (ferrite, pearlite, or cementite depending on the carbon concentration). This transformation actually changes the size of the crystal matrix, which locks in a ton of internal stress as atoms want to move around but can't. All of this internal stress must then be overcome by an external stress to move the atoms around, resulting in a much harder material.

Martensite requires extremely fast cooling rates (on the order of 100s of degrees/second), which is why most carbon steels are quenched to harden them. These cooling rates are only able to be achieved a little ways into the bulk of the material, so you usually end up with a hardened case made of martensite, and a softer more ductile core that is usually pearlite (layers of ferrite [pure iron] and cementite [iron carbide]) that form due to the slower cooling in the core. This is usually actually more desirable than an entirely through hardened piece, as the hard surface can resist wear and indentation, while the soft core increases the ductility and toughness which reduces the risk of fracture.

Thanks, I was a bit confused by the different allotropes. Interesting that the martensite transform naturally only happens on the surface (which as you say is actually desirable) due to the rapid cooling it requires, I didn't know that. But of course it makes sense that quenching doesn't instantly cool the bulk of the workpiece.

> Where there was copper, there was no tin, and vice versa.

There were some exceptions on the British Isles. Even some mines that had both.

Yeah, Cornwall was most famous for its tin, but there was a reasonable amount of copper too - particularly in the Carnon and Tamar valleys.

There were also very productive copper mines around Great Orme in North Wales, which would have only been a couple of days' travel by boat and were frequently visited as part of the same Atlantic Bronze Age trade routes as Cornish tin.

> Our ancestors 5000 and 10000 years ago were just as smart , intelligent and curios as we are today.

That sounds nice but axiomatic egalitarianism might, just might, not be empirically true.

We know that there are vast differences in all modern uniform populations we have tested -- intelligence is normally distributed and the differences between the tails are huge.

We also know that different populations have different distributions -- slightly different standard deviations, sometimes vastly different means.

Why wouldn't that also have been true at the dawn of history and in pre-history?

Since we do now know many alleles that influence intelligence and we roughly know their effect sizes (very small for almost all of them) and since we can actually sequence really old DNA in some cases, we can actually come up with reasonable guesses for how intelligent people were thousands of years ago.

And what do you know? They do differ. Or at least, their allele frequencies do for those alleles that we are pretty sure have an influence on intelligence. Some of them really do seem to have been pretty dim. Others not so dim.

PS: It's difficult to make an iron sword/knife/axe that is better than a bronze one.

>We also know that different populations have different distributions -- slightly different standard deviations, sometimes vastly different means.

Citation needed. This is at a minimum, highly controversial.

And I think the claim is that the distribution was more or less the same, not that they were all uniformly intelligent.

No citation needed -- from me, anyway. It's only controversial because one side lies.

On one side there are the phlebotomists, the geocentrists, the astrologers, the religious.

On the other side there is science.

> One of the axioms I go by is that people were never stupid.

Or in some cases, "poor, not stupid" [0], where even geniuses had no power or resources to pursue great innovations compared to the immediate priority of Not Starving.

[0] https://acoup.blog/2020/07/24/collections-bread-how-did-they...

"That old Copper++ is worthless, you need to try this Rust"

Ideas improve over time. So people in the past have worse ideas. This might include fear of change, and some mythological notion of an eternal golden way of life, which you must dutifully maintain by spending a thousand years not inventing pottery, and if anybody dares to try it, beating them up.

The improvement of ideas over time is a rather complex process.

It's multiple things working together. Typically you have to have an excess of calories which leads to free time in at least part of the population. While the 'fear of change' as gods fault is more of a post ad hoc rationalization of the horizon problem. That is any change in behaviors in the good times could lead to death in the hard times. Moving away from what works has risks.

Or, being static was not even adaptive, but was just a dearth of good ideas (ideas about ideas) that arose later.