Interesting set of links and news items in the September issue of Current Archaeology 354 – which begins with the Mesolithic site at Blick Mead near Stonehenge (change in climate in the 5th millennium BC) – see www.sciencedirect.com/science/article/pii/S2352409X18301871 – while we have 'rethinking Scottish crannogs' (see earlier posts on the News). Divers dsicovered they go back to the Neolithic era and were reinhabited in the Iron Age (but as artificial islands). In the Neolithic the crannogs were not so much located on islands, artificial or otherwise, but although they were surrounded by water (or a marshy environment) it was pretty shallow on three sides with just one side of the crannogs facing deeper water. Here divers found numerous Neolithic pots and presumably they were some kind of offering in order to bribe the gods to lower the water table – which is of course also a feature of the Iron Age (although the offerings at that time often included metal artifacts such as swords). Details of the excavation and finds can be found at https://doi.org/10.15184/aqy.2019.41
An even more interesting excavation on the Neolithic in Scotland comes from www.archaeologyreportsonline.com/reports/2019/ARO34.html … where we learn that organic material dated to the very beginnings of the Neolithic in Scotland, around 3800BC, may imply they arrived from across the North Sea, directly (with the inference they arrived by boat). The site concerned was occupied more or less over a period of 4000 + years, from 3800BC to the early medieval period (in the Pictish era).
In Science Notes (page 12) we have a study into changing population levels in Ireland – using statistics and maths. A large scale change in population numbers is apparent – but not a crash as in an epidemic but a slower more systematic decline. See https://doi.org/10.1016/j.jas.2019.04.001 … researchers from the University of Belfast used a statistical tool to calculate human activity using a database of 8800 C14 dates taken from archaeological contexts across Ireland. They discovered a widespread decline around AD700 which continued up to AD1100 – deep into the medieval warm period (which is by itself surprising and as yet not explained). The decline was apparent at all the sites investigated – so it was a nationwide feature. As such the same may be true of Britain as the population numbers in the Domesday Book are not exactly overwhelming. What caused the decline is unknown but famine, disease, migration overseas, or a combination of all three, may be postulated. Genetic investigation has shown a Scandinavian haplogroup arrived in Ireland between AD900 and 1200 and the new findings would suggest that combined with a decline of the natives it would not have required a very large group of Norse migrants to reach the levels of admixture seen in modern populations.