Successes in cultural evolution raises the variability in humans’ highest stage attained.

The model of hierarchical complexity characterizes behavior 1-dimensionally, by representing its order of hierarchical complexity. It results that interspecies behavior can be directly compared. From interspecies comparisons, 1 intriguing question is why humans evolved the most, attaining the highest average stage and the highest variability in the highest stage attained by adults. We hypothesize that population growth has been a major factor for shifting upward the average stage of development of humans, which, reciprocally, was a perquisite for cultural evolution. We also consider competition and selection as core processes that go hand-in-hand with the rise in stage. Results show that population growth and rise in stage are strongly positively correlated. The emergence of a metasystematic Stage 13 individual is possible with an increase of the population from 2 to 161 individuals; a paradigmatic Stage 14 individual emerges with an increase from 161 to 4291; and a crossparadigmatic Stage 15 individual emerges with an increase from 4,291 to 289,855 individuals. We discuss that acceleration of population growth might be a fundamental measure accounting for the rise in stage. We deduce that agricultural practices were, then, fundamental for liberating human evolution. Although we do not have sufficient data for quantifying the reason behind the highest variability in the highest staged attained by human adults, we suggest that variability increases with the increase in average stage of a species. Finally, we draw some conclusions in regards to current populations, predicting that India might witness the next wave of innovations.