If you’ve even remotely ever played with open source software you are very familiar with the idea of forking. The base principle is that for some kind of open source software, anyone is free to alter that code in however way they see fit and eventually run their own instance. If you’re not a software engineer, you should know that this model is probably the most successful one to build long lasting code an libraries. Coincidentally, most of the software with which we interact on a daily basis is built on open source libraries.
The blockchain world went a bit further with the concept of hard forking, where not only the software which operates and maintains the blockchain is duplicated and altered, but also the data itself. When a blockchain is forked, you have in practice 2 timelines from the same history, but with different futures.
If you owned 1 Bitcoin before the bitcoin cash fork, you owned 1 Bitcoin on the “core” blockchain and also 1 Bitcoin in the bitcoin cash fork. Obviously their $ value would be widely different, bringing a lot of confusion.
In many ways, Bitcoin reminds me of another chain: DNA. DeoxyriboNucleic Acid also contains its own history, going back all the way to the very first living cells. And DNA is also what makes each individual completely unique by defining physical traits, ‘defects’, and, some believe, a bit of our fate.
In Biology, I think hard forking is what scientists call DNA Replication.
DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance.
Even though this process is called replication, it is error prone and errors are called mutations. In practice, exactly like in the case of hard forks, the new “chain” is almost identical to the previous one, with only a very small set of differences. For blockchains, they may be the size of the block, and for DNA they may be the recipe for a protein which pigments the zebras’ hair and skin.
In nature, DNA replication is also the core mechanism to Meiosis, which is the act of “splitting” the genetic material in half. The purpose of Meoisis is to divide the amount of chromosomes in order to later combine it with another member’s genetic material. This whole dance is also known as sexual reproduction and is how most animal and vegetable species “conceive” whole new individuals: they are the “merging” of two chains, as long as they do not diverge too much (DNA is 99.5% common between 2 humans), resulting in a whole new chain.
Sexual reproduction is believed to be what eventually leads to diverse and more resilient populations and is the core of Darwin’s evolution theory: nature combines DNA material over and over again, and each new individual is “tested” against its environment. By definition, the individuals which are more adapted are the ones which have greater odds of survival or even just greater odds of finding mates… perpetuating their own lineage.
Sexual reproduction is where the DNA analogy ends for the blockchains. At this point, I do not think that “merging” mechanisms exists: once chains have forked, there is no clear way to recombine them. However, this would be an extremely powerful mechanism to run consistent experiments around them to make sure they evolve fast and adapt to new requirements in the best possible way.