I don't because I have taught a few old dogs new tricks. The last old dog I taught a new trick to was probably 120 years old in human years. But I taught him how to do the What's Up head nod and how to look cool while doing it. Before I taught him the trick he spent most of his day looking out the window and resting his chin on the window sill. So I started giving him a what's up head nod ever time I went out on the deck and after 6 months or so he started giving me one back. But it wasn't a very cool looking what's up head nod so I spent another year teaching him how to do the what's up head nod in a cool looking way. I bet I could also teach a 120 year old person how to look cool while doing a what's up head nod. Cheers!