3 ms·

4 billion years, but also massively parallel. Trillions of simultaneous random walking hill-climbers.

jcims 8y ago
This is one heck of a hillclimb: https://www.youtube.com/watch?v=aoCzZHcwKxI https://www.youtube.com/watch?v=aoCzZHcwKxI Pulling this completely out of my ass, lets say the ability to camoflage is 30 genes, ones to modify skin color, signalling to do it on command, mapping to specific parts of the body to create a specific pattern, all of the above for skin morphology, mental ability to map this to prey avoidance, all of the above for ink synthesis (glands, storage, ability to express on command). Let's further assume that those genes are expressed over 500 base pairs (woefully short) for better or worse. Somehow those genes need to be introduced into the genome to create a ninja octopus out of whatever its predecessor was. To date, all i've heard is that mutation is the source of this new genetic material. So somehow we need to mutate our way to these 500 base pairs. Let's divide that by ten as some kind of poor man's compensation for the flexibility of dna to handle noise and whatnot. So we need to introduce 50 essential base pairs. There are 4^50 possible combinations of these base pairs, or 10^29 in more recognizable numbers. Do we have 10^29 generations to introduce those? That's a lot of octopus.
- mhuffman 8y ago
  > Somehow those genes need to be introduced into the genome to create a ninja octopus out of whatever its predecessor was. Well no one is saying that a ninja octopus just appeared one day by chance. > lets say the ability to camoflage is 30 genes, ones to modify skin color, signalling to do it on command, mapping to specific parts of the body to create a specific pattern, all of the above for skin morphology, mental ability to map this to prey avoidance, all of the above for ink synthesis (glands, storage, ability to express on command). Let's further assume that those genes are expressed over 500 base pairs (woefully short) for better or worse. Think about the things that you said above. If one octopus out of the hundreds of millions of generations had one of the 30 gene changes that did one thing to its skin that was beneficial, then in short order (say a few thousand generations) that would be the dominant type of octopus. Then one-by-one the items that you listed could easily do the same. Some individually, others maybe at the same time. I mean there have only been a little over 100k generations since humans split from apes. So a lot can happen in the time spans you are talking about. Octopuses as a species are supposedly 296 million years old, hatch by the thousands, and only live 3-5 years, so 100 million generations of thousands of octopuses or so to get to where they are today.
  - XorNot 8y ago
    The other issue is that usually seemingly useful and complex systems are not "suddenly" created - i.e. they don't just appear. In living organisms almost every feature is an extremized or repurposed variant of some other system. Something like a bacterial flagellum for example is actually a special-case configuration of proteins which allow the bacteria to secrete compounds. (see: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632597/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632597/ and other resources - it's really interesting) So all the individual systems in the octopus camoflage system didn't just have to suddenly appear - they all would trace their function to other systems the octopus already had - i.e. its not "chance of this exact thing appearing" its "chance a mutation doesn't make the old system totally useless, while maybe providing a slight benefit".

This is one heck of a hillclimb: https://www.youtube.com/watch?v=aoCzZHcwKxI https://www.youtube.com/watch?v=aoCzZHcwKxI Pulling this completely out of my ass, lets say the ability to camoflage is 30 genes, ones to modify skin color, signalling to do it on command, mapping to specific parts of the body to create a specific pattern, all of the above for skin morphology, mental ability to map this to prey avoidance, all of the above for ink synthesis (glands, storage, ability to express on command). Let's further assume that those genes are expressed over 500 base pairs (woefully short) for better or worse. Somehow those genes need to be introduced into the genome to create a ninja octopus out of whatever its predecessor was. To date, all i've heard is that mutation is the source of this new genetic material. So somehow we need to mutate our way to these 500 base pairs. Let's divide that by ten as some kind of poor man's compensation for the flexibility of dna to handle noise and whatnot. So we need to introduce 50 essential base pairs. There are 4^50 possible combinations of these base pairs, or 10^29 in more recognizable numbers. Do we have 10^29 generations to introduce those? That's a lot of octopus.

mhuffman 8y ago
> Somehow those genes need to be introduced into the genome to create a ninja octopus out of whatever its predecessor was. Well no one is saying that a ninja octopus just appeared one day by chance. > lets say the ability to camoflage is 30 genes, ones to modify skin color, signalling to do it on command, mapping to specific parts of the body to create a specific pattern, all of the above for skin morphology, mental ability to map this to prey avoidance, all of the above for ink synthesis (glands, storage, ability to express on command). Let's further assume that those genes are expressed over 500 base pairs (woefully short) for better or worse. Think about the things that you said above. If one octopus out of the hundreds of millions of generations had one of the 30 gene changes that did one thing to its skin that was beneficial, then in short order (say a few thousand generations) that would be the dominant type of octopus. Then one-by-one the items that you listed could easily do the same. Some individually, others maybe at the same time. I mean there have only been a little over 100k generations since humans split from apes. So a lot can happen in the time spans you are talking about. Octopuses as a species are supposedly 296 million years old, hatch by the thousands, and only live 3-5 years, so 100 million generations of thousands of octopuses or so to get to where they are today.
- XorNot 8y ago
  The other issue is that usually seemingly useful and complex systems are not "suddenly" created - i.e. they don't just appear. In living organisms almost every feature is an extremized or repurposed variant of some other system. Something like a bacterial flagellum for example is actually a special-case configuration of proteins which allow the bacteria to secrete compounds. (see: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632597/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632597/ and other resources - it's really interesting) So all the individual systems in the octopus camoflage system didn't just have to suddenly appear - they all would trace their function to other systems the octopus already had - i.e. its not "chance of this exact thing appearing" its "chance a mutation doesn't make the old system totally useless, while maybe providing a slight benefit".