In science, the favored interpretation is the one that is the most simple, but still fits the evidence at hand. More complicated explanations are always possible, but are less acceptable. This principle in science is called parsimony.
Paleoanthropology is not a normal science. It is a type of historical fiction. Its purpose is to make sense (and cents) of the past, and to inform and entertain the educated public. Evidence should be interpreted in ways that are understandable, but not simple. A simple explanation will often kill a good story.
I have been visiting the Alta petroglyphs (helleristninger) in arctic Norway almost every summer for the past 40 years. This is beautiful rock-art, that has become a UNESCO World Heritage site. There are hundreds of figures carved in the glacially polished and striated rock at Hjemmeluft, Alta. The figures show similar motifs of people, boats, and animals, and were carved using similar techniques and styles.
Paleoanthropologists say that the oldest carvings are about 6200 years old (4200 BC). The youngest ones were below sea level at that time and cannot be more than about 2500 years old. Paleoanthropologists think that most of them were carved just above sea level as the land rose slowly after the last glaciation. The land is still rising about 2 millimeters per year. This interpretation of carvings near sea level makes them as old as possible, and as interesting as possible.
Paleoanthropologists divide them into four periods: the highest ones, now about 25 meters above sea level, are thought to have been carved from 4200-3600 BC. The other periods of carving were 3600-2700 BC, 2700-1700 BC, and 1700-500 BC.
Artifacts have been found nearby, showing that people were indeed living in this area as early as 10 000 BC. It seems reasonable that the Hjemmeluft petroglyphs were made as early as 4200 BC. But they could have been made by the same artist or artists about 500 BC. Not too far away are two other series of petroglyphs: Storsteinen ('4200-1700 BC') and Amtmannsnes ('2700-1700 BC'). They have different styles and it is obvious that they were made by different artists.
For paleoanthropologists, ‘older is better.’ For me, ‘simpler is better.’ I think that all the carvings at Hjemmeluft were probably made by the same artist or artists, about 500 BC. I cannot find that this parsimonious (and rather boring) hypothesis is ever mentioned in the published literature.
Here is a schematic illustration of the ages and styles of the four periods of carvings of Hjemmeluft, Storsteinen, and Amtmannsnes.
See Helskog (1988) Helleristninger i Alta: spor etter ritualer og dagligliv i Finnmarks forhistorie