I'm not completely convinced this is true. Many humans have retained this urge and I am inclined to suspect that if it was the only way to acquire meat or fish more people would return to it.
I don’t think it’s quite the same. Humans may enjoy hunting for sport or relaxation, and in many cases are required to for survival, but I don’t think we are subject to that irresistible instinct that drives predatory animals. In fact, people often view those who seek to kill animals as slightly psychopathic or lacking in some fundamental empathy - see the attitudes of many (including people who eat meat) to slaughterhouse workers on this thread, or the way we view people who hunt foxes, club seals, shoot lions and elephants on safari in South Africa, etc.
Someone upthread was asking for an alternative to slaughterhouses given that people will always want to eat meat. Maybe the alternative should be that anybody who wants to eat meat has to raise the animal and kill it themselves. Perhaps the ‘raising’ part could be done in small cooperatives since most people don’t have the required space, and then you could just turn up to kill your cow / pig / chicken etc when you wanted the meat.
I believe that would lead to a massive reduction in meat consumption, as many people couldn’t stomach killing the animal and would forego the meat before they agreed to kill the animals themselves. It would also return meat to the status of a luxury item enjoyed occasionally, rather than a cheap everyday convenience, as people would understand the true cost of getting it to the table.
It would also hugely mitigate the environmental impact, because far fewer cows, sheep etc would exist.
It would need to be carefully regulated to ensure the slaughter process was no more cruel (and hopefully much less cruel) than it currently is. Everyone would require a slaughter licence to show they had undergone training in how to kill animals, like a drivers licence.
I jest, of course. It would be completely unworkable and open to even more abuse than the meat industry currently is. But i think it’s interesting to consider, because I believe very few people would continue to insist on their right to eat meat if the blood of the animal had to be on their own hands.