Dr. Stone

[Ryllharu]

It's a stone age world, with wild animals all over the place. If the other two returned to Tsukasa's nation, and Gen doesn't find Senku alive anywhere, his body was carried off and eaten. The end.

It might have been better if Senku tore off a chunk of his coat with an animal skull, dirtied it up, and handed it over. But that isn't the deal Senku made with Gen. Any kind of trickery is more likely to make Tsukasa suspicious.

[Buffalobiian]

It's a stone age world, with wild animals all over the place. If the other two returned to Tsukasa's nation, and Gen doesn't find Senku alive anywhere, his body was carried off and eaten. The end.

It might have been better if Senku tore off a chunk of his coat with an animal skull, dirtied it up, and handed it over. But that isn't the deal Senku made with Gen. Any kind of trickery is more likely to make Tsukasa suspicious.

It's more about saying "I don't see evidence of Senku being alive" as opposed to "Senku is dead". Unless you see a body (and you'd expect Taiju to have buried him since he's a bro), you can't really prove the latter.

Don't forget that Senku survived in this Stone Age World by himself for the first year or something.