“You can't teach an old dog new tricks” is a saying
a) that recent scientific experiments have shown to be true for older people.
b) that only applies to dogs, cats and other non-human species.
c) that is outdated and scientifically incorrect.
Older adults can and do learn new skills—relatively easily. In fact, in properly designed programs, older individuals can benefit from training as much as, and sometimes more than, younger people.