Religion has a cost (lots of resources and time are spent on them) and they have lasted through time, therefore it is evolutionarily beneficial.
A small percentage of the population is psychopaths, this has an obvious cost to communities, but the pattern has lasted through time, therefore has a benefit. Likely it's for war/fighting/hunting.
Growing light sensitive cells has a cost in energy and materials, and has lasted through time, therefore it must have a benefit (sight).
This strongly suggests that SOMETHING is listening to that plant make noise and it either directly or indirectly benefits the plant.
Also, isn't saying a trait exists so it must be beneficial a bit of an over simplification? Couldn't a relatively useless trait hypothetically exist due to genes that are also related to some other relatively useful trait? It seems like a stretch to say any lasting trait must be beneficial, unless you can isolate it from other traits on the genetic level or otherwise through analysis. Traits can also cease being beneficial as we can see from the countless species that have gone extinct.
Sorry if this seems like I'm ranting, but I just need more convincing that this rule of thumb makes sense, and would appreciate being pointed in the right direction if I'm off-base.
The operative descriptive word describing those "useless traits" is cost. If nothing else, they have a cost of the energy and resources required to produce the relevant cells or whatever. Another organism that does not waste that energy and resources will out-compete the one building the useless trait. Natural selection will make it go away.
edit: alternatively, a bad enough trait could completely derail the development of a good train. Maybe dolphins born with 200iq brains develop some other kind of bad trait as a result of the same mutation that doesn't allow for the 200iq trait to permeate.
Any organism we see today may very well have unnecessary traits that evolution is in the process of removing.
I wouldn't want such people unchecked though.
It has a benefit to individuals. A benefit to the community is not necessary.
> Likely it's for war/fighting/hunting.
This is a non sequitur.
Nothing is all cost and no benefit, and nothing is all benefit and no cost either. You don't see people arguing that vulnerability to cuckoos is beneficial to the birds they parasitize. The benefit is real (you don't need to bother recognizing your offspring, because recognizing your nest is sufficient) but the cost is so much larger (your children all die) that it's obvious the birds would be better off with the ability to recognize their own young (and/or eggs). They don't have that ability... yet.
While the sounds don’t make themselves, they could be a side effect of something else… instabilities in the structural tissue, the plant straining to increase the movement internal fluids… who knows?
That said, I personally think there is communication between plants, or that at the very least it’s something like trying to mimic predator insect sounds. But could be that the vibrations themselves help move fluids around (as opposed to being a byproduct of something else that does)
>it could be explained as the incomplete or nonexistent development of something that is complex that is beneficial.
If it has a cost but doesn't have a benefit right now, it's going to get weeded out via natural selection in favor of variants of the organism that are not wasting the time and resources on that trait.
But to conclude your conclusion, you must also show that:
- emitting noise has cost (fairly believable)
- and that something listening to it is the only way to make it beneficial, which is far from obvious. (Could just be a way to dissipate energy, or to send signal within the plant, or to get rid of some chemicals, or many other beneficial things that doesn't involve something listening)