@futurebird

I assume you already know about the Baby Tooth Survey: https://en.wikipedia.org/wiki/Baby_Tooth_Survey .

@futurebird Fluorine in the teeth; dental work generally. (Orthodontics leave traces! Implants on titanium posts rather more so.)

The other thing is that this kind of thing is generally very coarse; "its diet was C4 plants" has been the result for jaguar skeletal remains. (They were ritual jaguars fed on corn-fed turkeys, far as anyone can tell.) Absolute proof of time travel would take something impossible at tech level like that titanium post.

@futurebird

For time travelers who were alive in the 1950s-1960s:

Traces of zirconium-90 in the teeth and bones - looks like that would be the end of the strontium-90 decay products.

There are plenty of other radioactive isotopes, of course, but strontium is special because biological processes react with it like calcium, meaning it rapidly gets incorporated into bones and teeth.

If a person were a time traveler how might that show up in their skeleton, eg in the isotopic analysis of their teeth?

If a person were a time traveler how might that show up in their skeleton, eg in the isotopic analysis of their teeth?

@futurebird so the thing about carbon dating

(note: we are not experts on this, this is our lay understanding)

it's based on the observation that a living thing ceases to take carbon into itself when it dies, which means its radioactives start to be a smaller proportion of its mass compared to things that are still alive

but that only helps measure duration since death

@futurebird there is a nuance, though, that we suspect must be part of this methodology when it's applied for-real, but don't know enough about

which is that the total isotope balance in the ecosystem is not necessarily constant over time. we have no intuition for how it would vary but suspect it's not uniform.

so if you had a time traveler who you knew just died, and they hadn't been in the present day long enough to have exchanged much mass with it, they might indeed be noticeable

@futurebird microplastics

@futurebird Individuals who lived between 1945 and about now have greater carbon-14 levels in their bodies (from the atmospheric nuclear detonations from 1945 to 1963) than anyone who lived before.

But unless more nuclear bombs get detonated, new babies born will soon have no more in them than people who died before 1945.

@davidtheeviloverlord

Well, at least one would know you'd have exciting times in your future.

60 million years ago is an interesting period in ant evolution. The ancestor of Titanomyrma was probably around and there are so many gaps in the preservation of insects you could see some really amazing things.

Before ending up like a fossil...

@futurebird though you wouldn't be able to tell when they were from specifically, and there would be plenty of "regular" explanations such as them having had unusual exposure to radiation during their life

@futurebird though you wouldn't be able to tell when they were from specifically, and there would be plenty of "regular" explanations such as them having had unusual exposure to radiation during their life

@ireneista @futurebird

At the coroner's office, after time travel has been invented:

Detective, writing into small notebook: "So, how long ago did the deceased die?"

Coroner, taking another large swig from a bottle: "Who knows? Maybe yesterday. Maybe tomorrow. Maybe right now."

@wakame @futurebird yeah lol the hidden premise of this scenario is that time travel is noteworthy in the setting, ie. not a normal part of society yet

@ireneista @futurebird

Time Traveler: "Time travel will been a rather recent invention."

Linguist: "You know what? I will simply go back in time and buy Microsoft shares instead of getting into a profession where I have to listen to eldritch abominations like 'will been'."

Time Traveler: "Microsoft? The burger chain?"

@wakame @futurebird they really should have known that that was always going to have happened

@ireneista @futurebird

Retrohistorian: "So what happened is this: A lot of time travelers, and I mean... a lot show up on April 4th, 1975, to buy a share of Microsoft.
And Billy 'Buns' Gates, always the entrepreneur, sells each of them a burger with fries, for $20, reselling food that costs $1.20 at the time.
After that, he basically bought a company named 'McDonalds' and rebranded it.
What do we learn from that? Always compare prices whenever you go."

If a person were a time traveler how might that show up in their skeleton, eg in the isotopic analysis of their teeth?

@futurebird on another note, we don't remember who wrote it but there was a short story once about time travelers who attempt to rob the library of Alexandria right before it burns down, but get caught by local law enforcement, who correctly deduce they're time travelers because......... they attempt to pass coins that are real gold, but all identical rather than showing individual variation in their manufacture

@ireneista @futurebird love that the local authorities were wise to time travel even back in the day