Because of the limitations of ancient medical equipment, the ancients were not able to recognize the nature of cancer, and there were no such advanced instruments in ancient times, so that cancer would not necessarily be detected. It may even be misdiagnosed as other diseases and die.
And the ancient people have a shorter life expectancy, some people do not even have the opportunity to get cancer, the vast majority of cancers are in the 40s and 50s outbreak, the age of the growth of the incidence of the disease will make the incidence rate gradually increase, but the ancient people have poorer medical conditions, usually live to the age of 30 years old died, so that has not yet survived the age of the cancer high incidence of cancer, so not many people get cancer naturally.
Again, the ancient people's living environment was healthier and the air was cleaner. And the interest of the ancients was to drink a little wine and poetry, a mahjong fight a cricket, raise a bird, entertainment, basically are relatively healthy. Modern people all day soak in electromagnetic radiation and environmental pollution and the pressure of life, smoking, alcoholism, late-night barbecue, easy to cause cancer, relatively, the ancients were exposed to less carcinogenic substances, living habits are relatively better, so the chances of cancer is relatively small.
And with the passage of time,many bacteria are getting stronger and stronger, and viruses are also evolving, so that what did not appear in ancient times may have appeared in modern times. Different environments lead to different diseases. It is also possible that it has been around for a long time, but we just don't know about it. Nowadays, there are so many new things and so many more disease-causing factors. So that the relatively monotonous environment in ancient times, will not cause great harm to people, in ancient times people are more reverence for nature, now human beings in order to money and interests, caused great harm to nature, many times do not comply with the laws of nature will be punished by nature.