I wonder how they could differentiate the age of the wood from the age of the construction

Just an educated guess but I am assuming the age of the wood is a good enough proxy to construction. Making the assumption that wood out in nature will decompose in short order (when thinking of the stated age). Being off a few thousand years is probably ok.

But somehow the wood is still intact 500k years later?

It was probably buried under anoxic conditions, which would weaken it and make it less suitable for new construction.

"Intact enough to be recognized" is a lower standard than "intact enough to be useful as a building material".

Kind of as other said, it was buried. From what I have read archaeological finds are about piecing together good guesses. Sure some wood is rot resistant but I suspect you would be hard pressed to find wood sitting outside for 1000+ years on the ground that early civilization would find appeasing to build with. Anything is possible but I am guessing it either fell natural or was harvested by those people and they decided to build with it somewhere plus or minus a thousand years.

From the Nature article posted by unwind, it sounds like they dated the sand surrounding the wood, not the wood itself.

Here [1] is the Nature article in question, if you want to dig in.

[1]: https://www.nature.com/articles/s41586-023-06557-9

Thanks! I'm sorry I didn't include that link. They say of the dating method:

> Younger samples are dated using single-grain quartz optically stimulated luminescence (OSL) and older samples by postinfrared infrared stimulated luminescence (pIR IRSL) from potassium-rich feldspars (Methods and Supplementary Information Section 2). The pIR IRSL approach used extensively in recent years²⁵,²⁶ does not suffer the problems that can generate large uncertainties associated with thermally transferred OSL (TT-OSL), as seen at Site C North (Fig. 1b)²⁰.

I had never heard of this archæological dating method before, but Wikipedia comes through as usual: https://en.wikipedia.org/wiki/Optically_stimulated_luminesce...

Not having read the full paper, I don't understand why they think the date at which the sand around the wood cooled from magma temperatures is relevant to when the carpenter cut the logs? Or maybe they're assuming the sand was exposed to the sun and optically bleached around the time of the carpenter, so any trapped charge is from after that? https://insu.hal.science/insu-03418831/file/MurrayEtAl-2021-... looks potentially relevant.

Yeah it's hard to believe this was done intentionally before the existence of stone tools... did they bite the notches?

Stone tools predate this carpentry by 2.9 million years, about six times the time between these carpenters and us: https://en.wikipedia.org/wiki/Stone_tool#Pre-Mode_I

Not really—the topic is about wood drying, and this Nature article is the expanded footnote about how long humans have been working with wood.

EDIT: Sorry, you were referring to the GP's interest in the historic part. However, to me it sounded like you were offering this Nature article as a way to go deeper on wood drying, not the athropological footnote. Mea culpa, I was reading too fast. Thank you for the link!