Human_defined intelligent_species neuron_count gradation_of_intelligence elephants human_achievement children_of_God anatomically_modern_man great_empires industrialisation human_history memory young_species age_of_intelligence shark_age cephalopod_age octopus_intelligence DNA analysis social_animal hunter-gatherer_millennia tame_dogs people_and_dogs agricultural_discovery agriculture_discovery discovering_agriculture flora_fauna geological_observation creator Beringia agriculture_and_hunting hunter_gatherer_inequality nomadic_lifestyles farmers_need_defending writing reconstruction humanity people_all_related untraviolet_radiation skin_pigmentation_differences group_migrates skin_colour eye_and_hair_colour hair_skin_colour race race_used_culturally nations_are_ancient nationhood Roman_Empire France King_Clovis_I