New cannabis units, ancient giants, and aging insights headline this week's science

ScienceAlert’s weekly roundup covers UK scientists proposing a standard THC unit for cannabis dosing; an 8-meter-tall fossil Prototaxites that stubbornly resists classification; the discovery of the world’s oldest rock art in Sulawesi dating to at least 67,800 years ago; the identification of tagatose, a natural low-calorie sugar that does not spike insulin; a gut-bacteria-driven syndrome where ethanol can form in the gut after meals; and new evidence linking the shingles vaccine with slower biological aging and reduced inflammation in older adults.