In world history, it uses BC/AD dating system. What are the true meanings of BC and AD? You can find the answer at https://www.gotquestions.org/BC-AD.html
Who is the creator of life table?
Read http://www.stat.rice.edu/stat/FACULTY/courses/stat431/Graunt.pdf for answer.
What does life table do?
To estimate the survival probability of a life time variable.
Is it good estimator? Well it is simple. Kaplan-Meier proposed another one in 1958. But it still didn’t take covariates into consideration. Cox (1972) proposed the proportional hazards model and since then survival analysis in statistics is well formulated. But Cox PH model has several assumptions: 1. hazard ratio does not depend on time; 2. The lifetime data has one endpoint (event); 3. independent assumption; 4. interest in hazard ratio, not the length of life time. To overcome these limits, many more models have been proposed. To read on, read “Analysis of survival data: challenges and algorithm-based model selection “. For more hands-on analysis using competing risks and multistate models, read here.