How are scientists able to say that a random species is extinct? Did they have to look everywhere?
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It’s more of a “eehhhh, good enough” kind of situation.
If no one has seen any of them for a good while, even when looking where they usually live, we assume they’re gone.
Sometimes we’re wrong, it happens.
science doesn’t like questions that they dont have answers to. now you’ve figured out that half of science is pseudoscience. bullshit fantasy to give you a good read. an article says’ we can “teleport now”. find out they can only teleport a “SINGLE ATOM” a few inches away. that is absolutely a lie.
For large endangered animals that have been carefully tracked for a long time, it’s easier to declare them extinct with strong confidence (species of rhino, for instance).
For smaller, more cryptic species it’s really just a matter of not being able to find any after several years of looking. But of course there’s some chance that it’s not actually extinct.
They take a guess and then say they were wrong when they find one. Check out the coelacanth as an example. Extinct technically doesn’t mean “we guarantee it’s gone”. It just means “we assume it’s gone”.
Evidence of absence is evidence. If we know a species makes nests in certain areas and they don’t anymore, then we don’t find the species there anymore. The lack of evidence for it’s continued existence is a type of evidence that helps form our conclusions.
Like if the police want to make sure nobody is in a house, they may stake it out. If nobody comes and goes from the house for a few weeks, they can be reasonably confident that the lack of evidence suggesting a presence means there isn’t a presence.
Of course, should a species be rediscovered because it was forced to relocate deep into say, the rainforest, it’s status would simply change when we got that new information proving they aren’t all gone.
Extinct isn’t so much a declaration of what is, as much as what we can currently find. Extinct means, “We done looked and didn’t see hide nor hair of it. Fuck knows.”
Short answer is no they don’t. It’s an assumption made when they can’t find evidence of modern encounters.
“Extinct” species are occasionally rediscovered in the wild. There’s also the long-standing issue that the distinction of what constitutes a “species” is more or less arbitrary.
e.g. historically one of the main tests for a “species” is genetic isolation, but to make the example gene-flow between domesticated dogs, Coyotes, and Wolves is quite free to the point that almost all wild coyotes/wolves have some mixed fraction of ancestry between the two species. Morphological distinctions to define species are also arbitrarily applied, to use the dog example again, the gap between a Labrador and a French Bulldog is bigger than many species gaps.
What a good question. Love this. Check out the [Coelacanth](https://en.wikipedia.org/wiki/Coelacanth) discovery.
When it comes to declaring a negative (that something is not true, does not exist, no longer exists, etc) most scientific conclusions are about looking long and in depth enough to say with confidence that we’ve investigated every reasonable possibility and can draw the conclusion that it is *overwhelmingly likely* that things are the way we’re concluding.
Confirming the positive is a lot easier. You know you’re 100% correct the first time you see a giraffe that giraffes are not currently extinct. Not finding a giraffe doesn’t mean you can confidently say it’s extinct just on its own, but eventually when you look long and thoroughly enough to say you’ve checked every place a giraffe could plausibly survive and found no evidence of one, you can say giraffes are likely enough to be extinct that you can treat it as they are.
It’s impossible to prove a negative. So we assume it’s true until proven otherwise. That is, we assume a species is extinct so long as we have no proof otherwise.
So if we found a species, but all the ones we were tracking died, we will assume it’s extinct until we find a new one.
Like all of science, we have to assume the universe is how we perceive it until proven otherwise.
It’s pretty easy to guess these days because while we can’t track each individual animal, it’s pretty easy to track the loss of their habitats, which is the real driver of extinction. If the forest is gone, the critter that lived in it is likely gone with it.
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