With higher THC levels than typically found in wild plants at the time, the cannabis was probably used for its psychoactive properties.
Federal laws hobble research into the dangers, and the potential benefits, of the drug.
Wider teen access to the drug is at issue, given concerns about its impacts on the developing brain.
Researchers at the 2015 AAAS Annual meeting said more studies are needed to understand the best dosing and delivery methods for medical use.
Headlines from the meeting will cover teen brains, earthquakes, medical marijuana, superhero vision, the Ebola outbreak, childhood deafness, and more.