How does Marvin Harris explain how the cow became sacred in India?India's SACRED COW story

Harris argues that there was a spiritual explanation
behind why the cow had become deemed a sacred animal.  As far back as 200 A.D., Brahmin
priests had began stressing the divine nature of the cow and had started instructing
followers to not engage in anything that would demean the animal.  Even prior to that,
Harris argues that the sacred Hindu texts, the Vedas, had expressly written in them
passages that strictly forbade the consumption and mistreatment of the animal.  As
Hinduism became more prominent in the region, its belief of the interconnectedness of
consciousness (what Harris terms as "Ahimsa") dictated that consumption, abuse, and
mistreatment of the cow would be a sin revisited upon the individual for time to come
and would be a bad reflection on their karma.  Harris also argues that the adoption of a
strict worship of the cow might have been done to create stark division between
themselves and foreign invaders who did not hold such beliefs.  Frequent clashes with
Muslims, who are not bound by the sacred cow conventions, and presumably greater clashes
with the British invaders, represented moments where the Hindus were able to define
themselves in opposition to "the other" with their strict worship of the cow and its
reverence.  In this light, spirituality and political identity converged into what is
now a fairly dominant national one.