In her exploration of humanity's relationship with animals, Mary Roach highlights the significant contributions of Mediterranean thinkers and artists to vegetarianism and animal welfare. She emphasizes the legacy of the poet Ovid, whose work 'Metamorphoses' expresses a deep concern for the suffering of animals. This suggests that ancient literature has long grappled with ethical issues surrounding animal consumption and treatment.

Additionally, Roach points to Leonardo da Vinci, who advocated for the equal valuing of animal lives and foresaw a time when beings would be treated with greater compassion. Saint Francis of Assisi's compassionate acts, such as requesting that grain be spread for birds on Christmas, further illustrate a historical tradition of caring for the natural world and respecting all forms of life, suggesting a continuous dialogue about our ethical responsibilities towards animals.