The laws of nature, as analyzed mathematically and descriptively by Ptolemy and Galen, bore an interesting, and perhaps not entirely accidental simil… - William Hardy McNeill

When variations could be so extravagantly successful, displacement of one humanoid population by another even more effective group of hunters must have occurred frequently. Survival was more likely for the more formidable in battle as well as for the more efficient in the hunt.

Religious history also offers another striking parallel between Rome and China. The Buddhist faith began to penetrate the Han empire in the first century A.D., and soon won converts in high places. Its period of official dominance in court circles extended from the third to the ninth centuries A.D. This obviously parallels the successes that came to Christianity in the Roman empire during the same period.

Like Christianity, Buddhism explained suffering. In forms that established themselves in China, Buddhism offered the same sort of comfort to bereaved survivors and victims of violence or of disease as Christian faith did in the Roman world. Buddhism of course originated in India, where disease incidence was probably always very high as compared with civilizations based in cooler climates; Christianity, too, took shape in the urban environments of Jerusalem, Antioch, and Alexandria where the incidence of infectious disease was certainly very high as compared to conditions in cooler and less crowded places. From their inception, therefore, both faiths had to deal with sudden death by disease as one of the conspicuous facts of human life. Consequently, it is not altogether surprising that both religions taught that death was a release from pain, and a blessed avenue of entry upon a delightful afterlife where loved ones would be reunited, and earthly injustices and pains amply compensated for.