Fighters who were world class in their 40s in the 1920s, 30s and 40s?

I doubt if there were many operating at a World Class level in their 40's. In 1920 the life expectancy was only 53 (USA). Normally, I would think there were some years of decline before death came knocking. Worse still, in order for a 45 year old to be boxing at that level in 1920, he would have had to have been born in 1875, when the Life Expectancy at birth was 39 years old (USA).

Whatever our positions on modern nutrition and medicine are, there's certainly no doubt that life expectancy has been increasing in the USA and World Wide really.