This story is at various blogs and web sites as well as media outlets. Mind you it has got buried underneath the wall to wall news stories on coronavirus but you can read about it at https://phys.org/news/2020-03-artifacts-guinea-neolithic-period.html … which is derived from https://doi.org/10.1126/sciadv.aay4573 (Science Advances). Agriculture of a kind developed in some parts of New Guinea at least as far back as 7000 years ago – and possibly even further back in time if it is an extension of jungle clearing and the favouring of particular plants. Archaeology has now caught up with the New Guinea neolithic. An exavation in Waim shows it had resulted in major cultural changes by 5000 years ago – after digging upp a repertoire of stone tools from axes to pestles, from figurative carving to a plethora of tools of unknown use and purpose.
The pestle was analysed under the microscope and shown to have been used to process plant material native to New Guinea. There was also a large block of stone that had been carefully ground and polished – half a metre long and 30cm wide, with a sharp edge. It was used in the creation of stone axes.
.. you can see the village of Waim sitting on top of that sharply defined mountain top.
There is also an older study on the subject — without the finds. See https://science.sciencemag.org/content/357/6356/1160.full