Okay so I have been thinking a lot recently as to what exactly counts as evidence, but in a slightly different sense to the way that it is being discussed here. No point in making a different topic because it is similar enough though. In my mind there are a lot of things that count as evidence that most people wouldn’t think of as evidence, but I’m really not sure where to draw the line.
It’s not so much from a “trusting someone” perspective but more from a philosophical perspective. Even with the current accepted trust levels on iNat there is plenty of room to not trust people (photos can be manipulated and dates/locations can be manually changed, so is someone saying that they saw a particular species but with no photo really that different?).
But anyway, I have a number of scenarios and in this case we will trust that they have been correctly recorded. I apologise in advance that there are so many of them, but I promise you that it’s interesting (well it is to me at least). The first ones may seem very obviously to be evidence, and the last couple may seem like obviously not evidence if you just think about them in isolation. But have a look at all the inbetweens. Where along the gradient do you stop?? I’m keen to hear what people think!
Is an organism evidence?
Is a photograph from a camera trap evidence? After all, nobody was there to see or hear the organism in person.
Is a museum specimen evidence? The location and date are certainly inaccurate if you just use when and where you took the photo of the specimen, but there’s still an organism there, and if you use the collection details then the location and date are correct.
Is a bone from a dead organism evidence? After all, it’s just part of the organism. What about a fossilised bone? It’s no longer organic. Sure, it’s not recent evidence, but is it evidence?
Is a dropped tail from a gecko evidence? The gecko is no longer here, but we know the tail must have been attached at some point.
Is a shed skin evidence? Again the organism is no longer here. What about a fallen leaf or branch?
Is a footprint or trackway evidence? After all, it’s not alive and never was. But what about a shell then? Shells aren’t alive, even though they are attached to the body. What about a fossilised footprint or impression?
Is a scat with remains in it evidence of both the animal that produced the scat, and the organism that it ate, the remains of which are visible in the scat?
What about a gall, or a feeding mark? We may not be able to identify exactly what species produced it, but is a swollen gall, chewn leaf, or scratched trunk evidence?
Is an illness or symptom evidence of the pathogen that caused it? Let’s just assume for a moment that we can accurately identify the pathogen based on a particular symptom. If I see an organism with that symptom, is that evidence of that pathogen?
Is a packet of chips (either type) evidence of a potato? It has been modified by humans, but there’s still a potato there. It has also been transported, possibly quite a long way, so you could say that the date and location are incorrect, but you cannot deny that there is a potato there.
Is a call from a bird or cricket evidence? No organism has been seen. If we could accurately record and depict a smell or taste on iNat, would that be evidence as well?
Is a photograph of a photograph evidence? The location and date may no longer be accurate, but surely it is still evidence that an organism was seen and photographed by someone. What if I have only a physical copy of a photograph that I want to upload to iNat, and to do so I take a photo of the photo and upload? What about a recording of a recording of a call?
Is a photograph of any sort evidence of humans? After all, photographs are a human invention. But ironically we may not necessarily see anything of humans or their artefacts within the photo. Is the very existence of a sighting on iNat evidence of humans who made the sightings and maintain the website?
I was privileged enough to watch a male lyrebird displaying recently, in which he imitated the calls of a number of different local native birds, including a kookaburra and a magpie. There were many of those birds in the area, but is his call by itself evidence of a kookaburra and a magpie?? After all, he cannot have imitated them if he did not hear them. He cannot make up a call like a human might, so we can trust that he did actually hear one, so how is it different from a human recording?
Vervet monkeys have specific alarm calls for specific predators. If a vervet monkey makes an alarm call that means “leopard”, is that evidence of a leopard? Yes, the monkeys could be wrong, but let’s assume for a moment that they are correct and did see a leopard. Would a recording of this alarm call be evidence of a leopard?
If a troop of chimps see a predator and start reacting to it - i.e. throwing things, trying to chase it away - but I don’t see the predator myself, is their behaviour evidence of the predator? I might not be able to identify it, but there is still an animal there that they are reacting to. What about a deer running away from a predator, but again I do not see the predator myself? Sure, maybe the deer was reacting to a noise it heard and there wasn’t actually a predator, but let’s pretend for the moment that the deer is correct and there is a predator. Does that count?
What about symbiotes? Is an observation of a healthy reef coral evidence of zooxanthellae? The coral would be bleached and discoloured without them, even if we cannot directly see individual zoothanthellae.
Land plants rely on mycorrhyzal fungi in their roots to help them extract water and nutrients from the soil. Without them, the plant would be dead. So is an observation of a strong, healthy plant evidence of mycorrhyzal fungi? We cannot directly see them, but without the plant would be dead if they weren’t there.
Is a fallen leaf or branch then evidence of mycorrhyzal fungi?? The plant could not have been strong enough to grow a leaf or branch without mycorrhyzal fungi, even if the plant may now be dead because the mycorrhyzal fungi have disappeared for some reason or other. After all, we say that a shed skin is evidence of an organism even if the organism itself is long gone and potentially dead.
Is then a large bleached or dead zooxanthellate coral evidence of zooxanthellae? They are no longer here, but for the coral to have grown this large it must have had zooxanthellae to help it.
Is a ripe fig evidence of fig wasps? The fig would be sterile and unripe without them, so to ripen it must have had wasps inside it. Equally, is an observation of the wasp then evidence of the fig? Many fig wasps are species-specific and can only emerge as an adult from a particular type of fig. If I see an adult wasp, it must have come out of a fig.
What about the yucca moth and yucca plant? They cannot live and reproduce without each other. The yucca plant is the sole food for the caterpillar of the yucca moth, so to see a large caterpillar (or adult moth for that matter), there must also be a yucca plant. And equally again, if I see a yucca plant is that evidence of a yucca moth? The pollination of the yucca plant requires a yucca moth, so does seeing a plant count as evidence for a moth? We know that a moth has been here, because otherwise there would be no plant.
The stick insect Parapodacanthus hasenpuschorum feeds exclusively on plants from the family Rutaeceae - is seeing an adult stick insect then evidence for a plant from the family Rutaeceae? Sure, the stick insect may have travelled a long way (they are very mobile and can fly quite well), but there still must have been a plant somewhere. You could argue that the location is not accurate, but when you record a sighting of something like a shed skin, you don’t say that the location is inaccurate because the animal is no longer there. If a grasshopper sheds its skin and then a huge storm comes in, and the grasshopper gets blown 5km inland and the shedding gets blown 5km out to sea where I find it on the waves from a boat, the grasshopper is 10km away at this point and was never even here in the first place, but you wouldn’t say that the location is inaccurate because it’s the location of the evidence, not the location of the organism. If a palm frond washes up on your local beach but there are no palm trees within 100km, you don’t say that the location is incorrect because the tree it came from is at hundreds of kilometres away.
So stemming from that, is an observation of any sort of herbivorous organism evidence of some sort of plant? If I see an elephant, is that evidence of the plants that it must have eaten to have survived and grown up until this point? What about carnivores? If I see a humpback whale, is that evidence of krill? If I see a lion, is that evidence of the other animals that it has eaten?
Is seeing Angraecum sesquipedale evidence of the moth Xanthopan morganii? The plant cannot be pollinated without the moth, so even if this particular plant had not been pollinated, its parents must have been.
What about further back in time? Assuming that the theory about avocado dispersal is correct, is an avocado evidence of the organisms that it evolved to be dispersed by? They may be extinct, so maybe it is not recent evidence, but the avocado could not have evolved without them existing at some point. What about other evolutionary questions? Is a butterfly with eyespots evidence of a visual predator? Is a wasp-mimicking beetle evidence of wasps, and is it evidence of the predators that it is trying to fool? These may not represent recent evidence and in some cases the other organisms may not even exist any more, but the simple fact remains that these features would not exist if those other organisms had not existed in the first place.
Is a photograph of an adult human face evidence of Demodex? Young babies do not have any Demodex, but it’s pretty inconceivable that an adult would not have them on their skin. So is a photo of a face evidence of Demodex? They are certainly there, but we cannot see them, and if they weren’t there the photo would not look any different.
Is then a photo of almost anything evidence of bacteria? It is almost impossible to not take a photo of something that contains bacteria unless you are taking a photograph of space, but even then the camera itself certainly contains some sort of bacteria. But if the picture didn’t contain any bacteria, it wouldn’t look any different.
Plenty to think about for sure. Apologies that it’s so long and there are so many examples, but I just keep thinking about all of these crazy things and coming up with more! What do you all think? Which of these counts as evidence and which doesn’t? I’m really interested to see where everyone draws the line, because the scenarios mostly change so gradually. So what do you think, and importantly why do you think that? Why are some things evidence and others are not??