Assuming you are using this as an idiom and don’t take it literally, I will argue that you CAN teach an old dog new tricks. Neuroscience tells us that while the aging brain does deteriorate, some of the aging process can be reversed through exercising the brain. In other words, you can help keep that old dog younger by teaching him new tricks!
One of the interesting things I learned while researching this is that old brains use different areas than young brains when learning and doing new things.
For fun, I included a link for you actually on dogs. You can teach an old DOG new tricks too!
well, i would go with the saying that you cannot teach an old dog a new trick. according to Psychology as our age increase out ability to adjust decreases. we tend to be rigid. we resist change because change makes one insecure in old age. it can be best understood by the exampe why our elders say it is not wise to get married after 30, simply because after certain age our habits become permanent and we find it hard to adjust or sometimes compromise, leaving apart bioogical changes. so, this may be one of the reasons why an old dog cannot learn new tricks.