For Part 1, see Truth Machines

A warm wind blows through an upland wood in east Africa. As the wind passes through the trees, a whistling sound can be heard. The trees are singing today. They raise their leaves to capture the morning sun.

Suddenly and without warning the relaxed mood is cut and a shiver runs through the entire wood. A giraffe is approaching. It is attracted to the whistling sound and to the delicious green leaves it knows it will find.

While the trees look thin and spindly, they are nonetheless prepared for attack. Each and every tree is completely covered in large thorns of a nasty sort. The kind that can punch through a leather shoe without pause.

But even still, it is not enough to deter the giraffe. With its dexterous mouth and long tongue it sidesteps the thorns on the first tree and begins to eat the delicate green leaves. In mere moments the tree is picked clean. The woodland shudders as the giraffe moves on to the next in line.

But at the next tree, the giraffe hesitates. This second tree is different. It stands proudly against the giraffe, whistling a tune of defiance. The giraffe is paralyzed for a moment, unsure of what to do.

Eventually the giraffe’s hunger ends its uncertainty. It pokes its head through the thorns in an attempt to get at the juicy green leaves.

This is a mistake. As the giraffe rustles the branches of the tree the whistling sound stops. Thousands of ants begin to pour out of the holes that cover the tree.

The ants attack the giraffe, biting and stinging its mouth, nose, and eyes. The giraffe pulls away, trying to shake off the ants covering its face.

Eventually the giraffe frees itself from the stinging ants. But with its sore and stung face, the giraffe decides that it has had enough leaves from this wood today. It stalks off to find a different wood. One that is less well defended.

Triumphant, the ants return to their tree home. Filled with gratitude, the tree presents to the returning warriors a feast of delicious nectar. The ants have their fill of the nectar and then return to their holes for a well deserved rest.

The tree stands proudly and begins again to whistle its defiant tune. It is an acacia tree and it is protected by acacia ants.

Whistling thorn acacias and their relationship with acacia ants are a classic example of mutualism, where two species intertwine and work together due to the net benefits each provides to the other.

The whistling thorn acacia tree provides large bulb cavities the ants can live in, and secretes an addictive sugary nectar to attract and feed the ants. In return the ants defend the tree from herbivores and from encroachment by other plants. The wastes the ants generate as they forage for food from the surrounding wood also supply nutrients to the tree and help it grow.

Acacia trees are fascinating, not only for what they are and their unique ecology, but also because they serve as a useful metaphor for the ecology of blockchains.

Blockchains have been widely described as distributed ledgers structured as a lengthening chain of blocks connected by cryptographic hashes. To translate this description: blockchains are databases (ledgers) stored on a network of computers (distributed) that keep track of record changes (blocks) using unique mathematical representations for each dataset (cryptographic hashes). To translate this description even further: A blockchain is a string of data on the internet organized by ID codes.

As a metaphor for the problem with this description, the equivalent description for the acacia tree would be: a woody plant with an elongated stem, branches, and leaves, often having thorns. Or: an acacia tree is a type of thorny tree. While these descriptions are technically correct, they miss the interesting part of the story for both the acacia and the blockchain. It is not surprising that many people who first come across this description of a blockchain wonder what all the excitement is about.

Blockchains are indeed distributed databases, however, what is interesting about them is that they are a special type of database that have established a unique mutualistic relationship with the humans that maintain them.

Similar to how acacia trees secrete an addictive nectar that attracts symbiotic ants, blockchain networks secrete an addictive digital synthetic currency to attract compatible humans. In return their symbiotic human gardeners defend the blockchain from bad actors and from encroachment by other blockchains. As the humans care for their partner blockchain they make investments which sustain and grows the network.

The bitcoin network is not just a distributed database, it is a distributed database which secretes bitcoins (or BTC) in exchange for maintenance of the network by humans running "miners". Famously BTC is issued at a fixed rate per block which halves every 4 years (the halvening) with a hardcap of 21 million bitcoins which will be reached in the year 2140. It is estimated that there are 10s of thousands of active bitcoin miners operating globally in competition for this secretion of bitcoin (much like a mature ant colony can be made up of 100,000 ants).

The Ethereum network is not just a distributed database, it is a distributed database which secretes ether (or ETH) in exchange for maintenance of the network by a set of humans running "validators". Contrary to BTC on the bitcoin network, the supply of ETH on the Ethereum network is not secreted at a fixed rate but rather at a variable rate that changes depending on activity on the Ethereum network. As network activity goes down, the issuance of ether outstrips the consumption of ether and the supply of ether goes up, incentivizing more activity. As network activity goes up, the consumption of ether tokens outstrips the issuance of ether and the supply of ether goes down, disincentivizing activity. In this way the Ethereum network regulates the number of symbiotic humans maintaining and using the network. The Ethereum network is cared for by a network of 100s of thousands of validators.

The crypto ecosystem can be viewed as a forest of blockchain trees maintained by a host of symbiotic human colonies. The blockchains and their human tribe counterparts compete with one another for attention and growth. But when the forest is threatened by a larger animal (like a government or government regulator), the humans swarm and sting attempting to defend their symbiotic partner blockchains.

Blockchains are the first databases in history to incentivize human maintenance, a unique and interesting form of digital symbiosis. They are best understood not as a technological revolution, but as an ecological one.