In the Mesolithic (of Scandinavia), forager-gatherer-hunters consumed colossal quantities, of shellfish, piling the shells, into huge hills and massive middens. The mesolithic middens are thought to, also, represent some sort of assertion of ownership,
demonstrating one groups' long-standing, continuous, past-and-so-future claim, to some stretch of shoreline.
Authors like Barry Cunliffe stress the sense of continuity, from the foraging Mesolithic era, through into the farming Neolithic era. In that Neolithic era, massive megalithic monuments seemingly substituted, for the prior massive middens. Massive burial "barrow" mounds, often heaped high over interior stone-slab-sided, cap-stone-roofed burial chambers (which, if exposed, look like Dolmens), represented the collection & concentration, of rocky rubble, strewn on the soil, into localized piles.
Large areas of land were "swept" of rocky rubble, presumably to improve plots & parcels for planting, pasturing,
i.e. for farming. The swept-away stones were, subsequently, incorporated into stone fences (= "bank cairns"), seemingly similar to what European colonists did in North America from the 17th century AD. The swept-away stones were also gathered into megalithic monuments, which were then devoted to the memory of ancestors,
i.e. burial barrows (hill = dirt) & burial cairns (hill = small stones). Like the Mesolithic middens, Neolithic burial mounds can be construed, to claim ownership over those surrounding lands, from which the debris & scree of stones & rocky rubble (and also forest cover) was removed.
Again, in the Mesolithic, shell middens seemingly suggest an assertion of ownership, over all lands, from which the shellfish were harvested (and their shells heaped into hill-high midden mounds). Plausibly similarly, Neolithic burial mounds may have meant, a claim, over all surrounding lands, which were "improved" and "put into production" (in modern terms), and from which all the rocky rubble was removed, collected, and constructed, into the burial mound monument.
Note, according to Francis Pryor's
Making of the British Landscape, the super-sized stone slabs, set up as the interior burial chamber, may not have been moved very far. In Wales,
Some of these tombs were constructed over large filled-in pits, which may have been dug to extract the capstone. Thus the stone that once lay below the ground was now hovering in the air.
Thus, seemingly practically, Neolithic western European peoples "worked around" the biggest boulders, building those sizey slabs into tomb chambers, essentially on site; and then filling in gaps in between the big blocks with smaller stones, gathered from farther a-farm-field; and seemingly usually constructing a "curb" retaining wall around the edges, of the entire outer mound. Thus, the overall structure had straight sides, with the hump of a hill over the top, so looking at least a little, like the vertical faces, of a Neolithic (long- or round-)house, with its thatched roof.
On top of all of that, those burial mounds were often aligned to (say) Winter Solstice sun-rises, or other combinations of particularly prominent Solstice/Equinox sunrise/set solar alignments. Thus, the burial mounds also
functioned, as (say) Winter Solstice sunrise "
detectors". Every (say) Winter Solstice, their architecture would create visually dramatic juxtapositions of blindingly bright sunlight, and deep dark shadow, as thin shafts of sunlight penetrated straight up the tomb passage entrance hallway (say), all the way into the back of the burial chamber. The visual effect would have been as dramatic as something from an Indiana Jones movie, as it happens.
Thus, the burial mounds marked ancestral
territories of painstakingly improved plots & parcels; and functioned as "
calendar date detectors", unambiguously, and dramatically displaying, some special annual date (often the Winter Solstice). By counting days, from those specially "detected" days (2 x Equinoxes + 2 x Solstices), Neolithic northwest Europeans could have kept an accurate calendar, for purposes of planning planting & pasturing. The suggestion seems to be, that they reckoned time, by day of season (
e.g. 1st day from the Winter Solstice, 2nd day from the Spring Equinox, 3rd day from the Summer Solstice, 4th day from the Fall Equinox).
So, ultimately, plausibly allot like Mesolithic middens, Neolithic monuments embodied land improvement, marked territorial claims, and "calibrated" some sort of solar calendar, for farming. Thus, they were, at root, built, for practical purposes, revolving around ("surprise")
food production, calorie acquisition.
Speculatively, by about
2000 BC, in Britain (at least), (some) northwest Europeans were, plausibly, keeping a solar calendar, essentially similar, to the protoRoman calendar of Romulus, which was basically a
Julian-like calendar, of
12 months x 30 days per month. If so, then the "modern" 12 month, 30-ish-day per month, current calendar, is essentially similar, to those of
4000 years ago,
i.e. western European peoples have been keeping to a current kind of calendar, for
many millennia.