Life expectancy in the US in 1927 (85 years ago) was only 59 for men, 62.1 for women. What I don't quite understand is where the number comes from. Does it mean that in 1927 people born that year were expected and projected to live that long? Or does it mean that looking back, people born in 1927 have in actuality lived that long? In any case, they are outliers for their generation.
Confounding your observation is that these people at the Dean Martin roast were all part of a special group of friends and colleagues of Dean Martin and part of a special group of colleagues from an unusual era of humanity--an era of popular culture where people like that appear in your home almost like family (I always considered Lucille Ball to be like a 2nd mom to me I saw her on TV so much in my childhood). It makes sense they'd keep coming back to this event until they were all gone. There is no other outcome but to eventually see the oldest celebrities at this event.
They are also members of a generation that experienced incredible things: medical discoveries, affluence unheard of for our nation and for ordinary people living in it, enormous advances for women, etc. They also lived as children during a time when fast food and junk food were rare, pesticides and pollution had not yet accumulated to current levels, and large parts of the globe were still pristine, untouched and unknown. Children still played outside. Labor-saving devices did not exist. Television didn't exist. Etc.
It should be interesting to see what can be observed of people born when I was born, or born more recently. Will we live long? Will we be healthy in our old ages? Will xenoestrogens do us in? Will pollution and the loss of biodiversity in the world make us sick?