Yes it's something I've researched because I have a science degree and am seeking a second one (and also because of my cultural sensitivity to native tribes like the Yurok who revere the salmon for allowing their people to survive 7000 years, though the rest of their diet was mainly nuts, berries, greens and teas they do eat fish which they caught sustainably).
1) What caused us to evolve was fire, not meat. Apes are currently close to discovering how to build a fire and researchers are wondering if we will see them evolve right before our very eyes. Fire allowed greater bioavailability of critical nutrients - one of the reasons I'm not a supporter of raw veganism (though I don't try to stop raw vegans from being raw) ...we can simply digest and absorb nutrients more efficiently from cooked foods, with a few exceptions where raw is better. Humans evolved because of calorie density ...something we have no problem obtaining now as Western people in a culture that literally throws food in the garbage.
https://www.smithsonianmag.com/science-nature/why-fire-makes-us-human-72989884/
https://blogs.scientificamerican.com/guest-blog/human-ancestors-were-nearly-all-vegetarians/
https://www.huffingtonpost.com/entry/evolved-to-eat-meat-maybe-not_us_58bc7e4be4b02eac8876d020
http://vegnews.com/articles/page.do?pageId=9163&catId=1
2) Even though the biology I took was specifically geared towards science majors and pre-meds, I think any one who took college biology at school that wasn't Bob Jones or Trump U should have learned that humans were not "made to eat" anything. Humans have the capability to eat anything, and our adaptability helps us to thrive as a species, but we were not "made to eat" any particular food. In fact studies of our teeth and digestive system strongly suggest herbivorous rather than carnivorous ancestors. This beautiful adaptation humans have is exactly why you can tell those silly heads that veganism is a perfectly acceptable diet for modern humans - precisely because we are adaptable.
3) Evidence suggests that vegetarians and vegans have smarter children with higher IQs than people who eat a traditional Western diet. However, correlation is not causation, scientists aren't sure yet if it's because of veg diets or because smarter people are more likely to go vegan (and therefore simply pass on smarter genes). Any health arguments against children being vegan are typically based in poorly planned diets, crazy abusive parenting in a small minority, and the "vegan children are smaller in stature" argument only applies to age 5, at age 10 vegan children are usually a similar height as their cohorts. Of course they're going to weigh less - Western children are obese.
https://www.petakids.com/parents/vegetarian-family/meat-suitable-children/
Oh and there's this:
http://news.bbc.co.uk/2/hi/health/6180753.stm
https://www.psychologytoday.com/blo...-vegetarians-are-more-intelligent-meat-eaters
4) Yes, there are tribes who would have not survived without fishing 1,000 or even 200 years ago. This argument doesn't stand up to the light in regards to factory farming, animal agriculture, and commercial fishing industries. Unless these dipshits actually live on a reservation and only gather their food with their bare hands, they need to sit down and shut up.