Complex sentence: Poisons have been used for many purposes across the span of human existence, including as both weapons and anti-venoms and medicines, and have allowed much progress in the branches of medicine, toxicology, science, technology, among others.
Split into simpler sentences: Poisons have been used for many purposes across the span of human existence as weapons, anti-venoms and medicines. Indeed, poison has allowed much progress in the branches of medicine, toxicology, and technology, among others.