> Is there a direct source for the healthspan claim?

I do not know one that directly compares numbers so I've pulled from a few sources.

Consider Americans: here [0] is an actuarial table from the US CDC which lists % of adults with some chronic conditions by age (diabetes, cardiovascular disease, chronic obstructive pulmonary disease, asthma, cancer, arthritis) Of note is that nearly 70% of adults 55-64 are diagnosed with at least one condition and 37% are diagnosed with at least two conditions. This paper [1] says that two thirds of Americans of any age die from a chronic disease.

Consider H-Gs: The paper in the earlier comment as well as the paper it references [2] indicate that H-G death from degenerative disease is relatively rare. At age 60+ about 24% die from degenerative disease. A H-G population in Bolivia has 5x less coronary artery disease than western counterparts, even in old age [3]. This is not an apples-to-apples comparison of healthspan but it does give some idea of prevalence of chronic disease in the two populations.

Some comparisons of population disease were made by those studying indigenous people under colonial administration [4]:

"Throughout his studies of isolated populations on native diets, Price was continually struck by the contrast of native sturdiness and good health with the degeneration found in the local white populace, living off the “displacing foods of modern commerce” such as sugar, white flour, canned foods and condensed milk. Nowhere was the contrast more evident than in Africa. In addition to their susceptibility to chronic diseases such as cancer, heart disease, intestinal problems, appendicitis, gall and kidney stones and endocrinological dysfunction, the Whites also showed little resistance to infectious diseases carried by mosquitoes, lice and flies. “In all the districts, it was recognized and expected that the foreigners must plan to spend a portion of every few years or every year outside that environment if they would keep well. Children born in that country to Europeans were generally expected to spend several of their growing years in Europe or America if they would build even relatively normal bodies.”1 By contrast, the native Africans exhibited a very high tolerance to infectious disease including malaria carried by mosquitos, typhus and fevers transmitted by lice and sleeping sickness borne by the tsetse fly."

A large part of this may be due to diet. The China Study [5] compares provinces before and after the introduction of western style cuisine and finds this change associated with increases of chronic disease, especially cardiovascular and cancer.

It is not a simple comparison, but I think there is a case that outside of accidents and infections the average H-G may be healthier than the average industrial human.

[0] https://www.cdc.gov/nchs/health_policy/adult_chronic_conditi...

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5876976/

[2] https://gurven.anth.ucsb.edu/sites/secure.lsit.ucsb.edu.anth...

[3] https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

[4] https://www.westonaprice.org/health-topics/traditional-diets...

[5] https://en.wikipedia.org/wiki/The_China_Study