When many animal and plant materials are comparable to modern materials, why would any civilization develop metal working?

Question

So, in the setting I've created, there are many animal and plant materials which are comparable to modern materials and some even greater than what can be made today.

For example, there are molluscs with shells that are comparable to bronze, large lizards whose scales are like iron, predators that have large teeth as strong as high carbon steel and some rare flying monsters even having naturally formed carbon nanostructures within their very bones making them stronger than steel but lighter than plastic.

This extends to plant life as well with some trees with wood that is stronger than the strongest wood in our world and vines that have a tensile strength greater than Dyneema rope.

Why would anyone waste their time with copper, bronze, iron, or low quality steel when a dagger or spear point created from a creature's tooth works better, why have a bronze and even iron sword when a club with animal teeth along its edge works better, and why make suit of metal armor when a fitted suit of sea shells and lizard scales works better, is more comfortable, and weighs less too?

However, this raises the question, in a world with so many natural plant and animal materials comparable and better than what can be made with modern technology why would any civilization develop metal working to make metal comparable to what already exists?

Answer 1

Tools and parts won't grow on trees

When people were primitive, they used stones as tools. There are plenty of stones for use, but they almost never have a shape that a tool needs. What was a major advancement for humanity is a skill to shape stone, creating stone axes, spearheads and primitive knives.

Iron-hard natural objects would be very difficult to utilize, because they will be very difficult to reshape. Stone can be chipped away. Cutting steel or even bronze requires stronger tools, which in modern world are almost always powered. Metallurgy and metalworking is taking advantage of the fact that metal can melt or become very ductile at high temperatures (as @AlexP noted). If natural objects of this world can't do that, people would be stuck with natural shapes. They may be able to go long way with that if suitable knife-like and needle-like shapes are available, but eventually this would become a technological dead end.

Metallurgy would be a niche technology in antiquity, but as limitations of natural shapes would become more and more restrictive, metalworking would take over and surpass the use of natural hard objects.

On the other hand, this is your world and you can make tools grow on trees - and this can be quite a story with a lot of fun!

Answer 2

Art. Metal has a look and feel unlike other substances. Jewelry was historically a major domain of metal.

Electricity. All those lovely wires need metal. As soon as someone figures out that lightning can be bottled, metallurgy will take off.

Other useful properties. Metal can be cast, can be machined, can be drawn into wire, can be rolled into sheets, can be hammered or forged into any shape. Metal is elastic, it is not brittle, and it is about as strong in tension as it is compression.

Any season. Metal can be “harvested” year round. It doesn’t migrate. And it doesn’t cry in pain when you mine it.

Nothing is free - those tough animals and vegetation are high risk to harvest, and require a different set of skills, akin to mining - it might be easier to work with stone or metal

Weight can be an advantage - density is the desirable quality of a bullet; similarly, you do not want an arrow to be too lightweight. Even if you can have a super light, super strong arrowhead, it has to have the mass to have kinetic energy to do actual damage against those tough creatures.

Avoid hunting/farming - Similar to the any season point to have to farm or hunt for the materials is a larger time sink then if you were able to create a material/item on demand system.

Metal by-products are useful too - Iron oxide, aka rust, is commonly used for creating red building materials such as paving slabs. Steel aggregate, aka slag, is used for high load bearing road surfaces as it has excellent grip and compression properties.

Answer 3

How exactly similar are those equivalent? Because even if a lizard skin is as hard as steel, if you can't melt and shape it, it is clearly not as useful as steel. Your society will start with scrappy tools that are much better than what they would get with the scrappy tool they would have made

Herding ain't cheap

What will immediately force your civilisation to find an alternative to animal resources is that as soon as you sedentarize and can't spend your day looking for a lizard

Unless your lizard with impervious skin has good meat, it is hardly justifiable to have a herd of every single useful material

And raising just for material reasons is just not doable until you have industrialized your farming technique. The expense of raising stock is the most terrible of all in the period: food. With how scarce it is, you certainly can't afford to spend it to not get at least some food back

If you can get good material on top of a good amount of meat? cool. Raising a weird porcupine who tastes like shit but whose quills have some great use? you'd rather eat.

I wish I had a good joke with plants

Pre-industrial society still had a tendency to deplete their forest fairly quickly. Look at the amount of primary forest left in Europe, heck, Louis XIV planted a full forest because he wanted to build a fleet but there was not nearly enough trees left in France to do what he wanted

You will soon enough run into the same problem with the plants, they take a long time to regrow and it is quite hard

What mining solves is that you just have to use people to mine and it is extremely scalable. Iron and bronze were rather shitty materials, probably not as good as teeth and wood, but they were much more scalable.

Answer 4

I mean, the easy answer is they wouldn't. They might discover that the ground has metals but not care because there's plenty of lizard scales laying around.

But if the point of the exercise is to specifically think up why they would still get into mining then there's all sorts of possibilities:

Sheer volume. Mining iron surely works out better in terms of "economies of scale" than herding. Iron in the ground is sitting there waiting to be mined. Herds of steellizards would need to eat, poop and do all the things steellizards need to do and that surely requires space and handling and probably works great on a small scale but breaks down when you need to build skyscrapers. Iron mining actually gets more efficient the more of it you need to do (you can just keep making bigger and bigger machines to extract and process it).

Food scarcity. Any animal that has steel for skin must have a heck of a diet. That's a lot of mass that has to come from something. What's the ratio for tons of steel produced by lizards versus tons of whatever it is they eat? Maybe what they eat is rare and only exists in specific biomes and is not, itself, easy to farm.

Comparable to, but only in some ways. You say the animal product is "comparable to" a metal but in what way? Metals have a lot of properties. How brittle is it? What's the melting point? How easily does it corrode? Is it magnetic? What's the weight per volume? How conductive is it? Late civilization might answer your question right there: maybe the animal products are non-conductive. Or the animal products actually are not metals and therefore cannot be smelted or have their properties easily changed. (e.g. "steel" is not one thing. There are lots of different steels. Different combinations of ingredients can produce steel with different properties which can be useful. So maybe an animal can give you "steel" but if it can't be tinkered with as real steel can, to modify its properties, then its use is limited.)

Answer 5

Unworkability
Scales and shells are too hard and/or brittle to work and thus can't be shaped as desired.

They Don't Scale Up
Spider silk is stronger than steel in some very useful ways but is far harder to get enough useful quantities than mining+smelting, of all things!

Undesirable Traits
Those that can be worked and scaled up are susceptible to pests with even tougher teeth, fungus or bacteria that naturally degrade the material. Another possibility is that the material is toxic or an allergen for most humans. If this is an alien planet, that's actually pretty reasonable.

Answer 6

We have real-world examples of this. Up through the 19th century, we hunted whales in order to harvest various oils that their body produces. These oils were highly desirable as lamp fuel, and were also used as lubricants, rust inhibitors, soaps, margarine, and medical products. In the last half of the 19th century, we turned away from these animal products in favor of artificial oils derived from petroleum. The reason? Whales had been hunted nearly to extinction. Demand for these products had long outstripped the ability for animal sources to supply adequate raw materials. We were harvesting whales an order of magnitude faster than they could replenish themselves. Instead, petroleum supplies were abundant and available much closer to industrial and population centers (thus cheaper to produce).

Animal sources will almost always suffer from this limitation. Plants have much shorter life cycles, so you can often mass-produce them in sufficient quantity to meet your ever-changing needs (we call this farming). If you can plant and harvest them in the same year, then they might be mass-producible. If your ultra-strong trees or vines require 10 years to grow to maturity, however, you might have a problem. We used to use parts of willow trees, poppy flowers, etc. for pain relievers. Those plants are far from extinct, but we don't farm them for medicinal purposes any more. Instead, we learned how to isolate the active ingredient and synthesize it from artificial sources. Aspirin can be mass-produced from artificial sources significantly cheaper and easier than from natural sources, so we no longer farm plants for these chemicals.

Your world would undoubtedly use similar logic. When demand for materials outstrips what nature can sustainably and conveniently supply, people will turn to other sources. They'll either do it once the cost of the animal/plant source exceeds the cost of the artificial source, or once they've driven the natural source to extinction.