I think people aged quicker back then. Even teens looked more mature than our kids do today, or so I've noticed.
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I think you hit the nail on the head, quite frankly! that was another factor for the 'aged' look he had later in life.
The other thing I find interesting is the some health reports note that we didn't have heart disease in the late 1800s and early 1900s as we have today. Some claim it's due to the unhealthy fats and processed foods that were developed as the 20th century progressed.
I'm sure the popularity of smoking also factored in, and Ty (as said many times before) was quite heavy--but who thought of it then?