: Typically use both thumbs for high-speed typing or a single thumb for "swiping".
In humans, the physical structure of the thumb changes remarkably from infancy through adulthood. mature and young thumbs
: A person's "texting thumb" often reveals their age generation. : Typically use both thumbs for high-speed typing
: Young thumbs in children contain growth plates (physes) made of cartilage, which are responsible for lengthening the bone. As an individual matures, these plates calcify or "close," and the bones reach their adult size and shape. these plates calcify or "close
: More likely to use a "hunt and peck" style, often holding the phone with one hand and typing with the index finger of the other. "Thumbs" in Gardening (Maturity vs. Youth)