At https://malagabay.wordpress.com/2017/04/06/deranged-dating-intcal13-and-… … without taking on board the Heinsohn AD revision, or indeed, his BC revision, it is interesting to note that it isn't just SIS authors who are sceptical of C14 calibration. I don't personally understand the reason why calibration has been re-calibrated recently (back in 2013) as it must cause a lot of confusion when dating archaeological material. For example, the 2300BC scenario is now dated to around 2500BC, opening up a massive gap in archaeology. Is this why they think Neolithic Britain was depopulated – by a plague or whatever? What is worse, if you have a few books on the shelves that are written in the old dates – they are now invalid. Not just books, but articles as well. It's okay for new students that are learning the new dates (and are not hampered by the old calibrated dates) but for the general public the whys and wherefores are not forthcoming – unless you subscribe to Radiocarbon journal (see for example http://www.radiocarbon.org/IntCal13.htm ). Why have they done it? Tim Cullen is one of those guys with a hefty dose of scepticism about a lot of matters, and one has to take some of his stuff with a pinch of salt, but when it comes to the radiocarbon methodology he has some real questions that require some answers.
If that was all I would not have bothered posting this but at the end of the blog post there is an interesting comment by one thx1138 who explains that not all plants absorb C14 to a great degree. Therefore, C14 dating on plants may be invalid. This is interesting – but no doubt taken into account by scientists, but it is a fact that plants are often used to provide a date at archaeological sites (in the form of seeds, nuts, charcoal etc). Is he right?
Tim Cullen has another go at C14 methodology at https://malagabay.wordpress.com/2017/04/09/deranged-dating-goal-seeking/