def sv_validate_priority
    date1 = self.subject_taxon_name.cached_nomenclature_date
    date2 = self.object_taxon_name.cached_nomenclature_date
    if !!date1 && !!date2 && date1 > date2 && subject_invalid_statuses.empty?
      soft_validations.add(:type, "#{self.subject_status.capitalize} #{self.subject_taxon_name.cached_html_name_and_author_year} should not be younger than #{self.object_taxon_name.cached_html_name_and_author_year}")