Wonder if cooking meat gives humans an advantage there. Of course, going vegetarian would bypass that altogether.
Bovine leukemia virus relation to human breast cancer: Meta-analysis - ScienceDirect
Viral Oncology: Molecular Biology and Pathogenesis
Possible cancer-causing capacity of COVID-19: Is SARS-CoV-2 an oncogenic agent? - ScienceDirect
I'd wager that cooking can inactivate most viruses, depending on the temperature. But what you do before the heating process also matters. Cooking at home, normal cooking, can get messy. In a lot of places, people even buy freshly killed animals or kill the animals at home (usually chickens or fish).
People usually treat as starting simultaneously with the industrial era. A better date range puts it earlier:
(middle of the 15th century)