An Age Of Peace Or Violence?
Research among contemporary hunter-gatherer societies in the 1970s and 80s found some had shockingly high levels of deaths by violence - higher than modern cities  - yet some other hunter-gatherer societies had 'little or no recorded violence and little or no evidence of violence have been observed in diverse climates and terrains all over the world'
Indeed, the Malayan Chewong tribe 'have no mythology of violence and no words for quarrelling, fighting, aggression, or warfare.', and most hunter-gatherer tribes 'have virtually no property crime, and nonlethal violence tends to be low...[Also] rape and other forms of violence targeting women are relatively low.'
However, 'the origins of farming saw an enormous surge in killing,' and of massacres of whole village populations. This is explained by 'increasingly packed populations... concentrated into the world’s first sedentary villages and therefore uniquely prone to food shortages and periods of starvation.' Scarcity caused by the boom-and-bust farming economy and frequent plague pandemics seems likely to have resulted in violence and attacks.
But if others had little or nothing, what was the point? The Vikings only started raiding Britain when the British standard of living had risen enough for there to be something worth pillaging. Poverty doesn't cause wars. Wealth inequality does, and in Neolithic society there was equality: everybody had nothing, or everybody had enough. Rarely did any one group have significantly more than another.
However, there is one other factor that argues powerfully against high levels of violence during the British Neolithic: monument building. People who build monuments together don't readily start killing one another. What underpins monument building are two other factors: a shared belief in, and reverence for, their ancestors predicated on reverence for the dead, and organised by a unifying 'priesthood', and also large scale religious festivals that brought everyone together for religious observances, trading, feasting and marrying.
'Society' was all about shared and sharing experiences, while bloodletting was exorcised, ritualised and organised through sacrifices, human and otherwise. There's nothing unexpected about human sacrifices at Garn Goch: Egyptian pharoahs ritually sacrificed and buried their entire retinues, and Julius Caesar reported that Celtic Druids did the same. There are 20,000 urns of sacrificed Phoenician children, and the Aztecs reportedly sacrificed 80,400 people in re-consecrating the Great Pyramid of Tenochtitlan in 1487. Human sacrifice was probably enough to satiate the blood lust of most people. Equally, sports events at these festivals would have enabled young men to blow off their testosterone, and show off their muscles without unstructured violence.
We can reasonably assume that monuments, ancestor based religion, and festivals attracting people from great distances, would have minimised larger scale, unstructured violence in the British Neolithic. In the Iron Age, wealth generation and socio-economic inequality created the need for castles/forts. By contrast, in the Neolithic they built large monuments to welcome many people in, not small forts to protect the few from the many.
Left: Vikings. Centre: the sacrificial Red Altar at Stonehenge. Right: skull wall of the sacrificed dead (Mexico). See copyrights.