Why Humans are Carnivore - Persistence / Subsistence Hunting

This one is not so much about complete carnivore but about why we should eat meat and why we should prioritise it. After all, if hundreds of thousands of years of evolution drove us to walk upright, sweat, shed fur for hair, springy legs and feet and a digestive system optimised to process fat. So humans were born / evolved to run but we did so in order to hunt animals to give us the fat we needed to thrive.

Lets have a look at some of the literature, note that these were just a few of the many articles I came across and several of these are themselves reviews that reference many articles to support these hypothesis. At this point it is a fact that humans evolved the way they did because of / for their meat based diet. Evolution works on such grand timescales that we are essentially the same beings as we were 10,000 years ago and as such are still a species that is has been moulded through time to live and thrive off of meat. It is the drive to hunt that meat that has led to use being so good at endurance activities. 

Hunter, P. (2019). The evolution of human endurance. EMBO reports, 20(11). doi:https://doi.org/10.15252/embr.201949396.

The article above is an interesting read, itself bringing together multiple sources. It states that humans were under selective pressure for their ability to hunt where they would rely on their endurance. It is worth noting that the majority of animals that we would have been hunting were easily faster than us over short or even middle distances and it is just over the longer distances, so several miles, that we had the advantage. It states that unlike other primates we had become properly omnivorous at this point i.e. other primates didn't need meat but humans do. 

Some of the adaptations listed include: 

• Temperature control - Loss of fur, sweating "becoming hairless was clearly associated with adaptation for more efficient cooling via sweating and therefore higher endurance."
• An adaptable heart - "the human heart has evolved to respond to training, being initially adapted at the same time for short bursts of intense activity or sustained endurance at lower rates of energy conversion"

Bramble, D.M. and Lieberman, D.E. (2004). Endurance running and the evolution of Homo. Nature, [online] 432(7015), pp.345–52. doi:https://doi.org/10.1038/nature03052.

The above table, provided by the above article which I found freely accessible through Google Scholar, shows a list of human adaptations that make us well suited for long distance walking and running. When was the last time you saw a plant run away from you? The concluding statement of the article is as follows: 

"The hypothesis that ER evolved in Homo for scavenging or even hunting therefore suggests that ER may have made possible a diet rich in fats and proteins thought to account for the unique human combination of large bodies, small guts, big brains and small teeth52,63. Today, ER is primarily a form of exercise and recreation, but its roots may be as ancient as the origin of the human genus, and its demands a major contributing factor to the human body form."

Cassinello, J. (2021). The human hunter as predator: A new role under a food web restoration scenario. Journal of Arid Environments, 186, p.104420. doi:https://doi.org/10.1016/j.jaridenv.2020.104420.

This paper discusses the evolution of humans as predators. Again it is freely available but to quote some of the main points. All the below are direct quotes from the article. 

• Pre-Neolithic hunter-gatherer populations were fully integrated in natural systems, they played an ecological role as top predators
• During human evolution we develop an unparalleled predatory capacity (see, e.g., Marlowe, 2005)
• The fossil evidence on the use of tools indicates that our ancestors probably began to feed on carrion and even to hunt 2.5 million years ago (Shipman, 1986; Larick & Ciochon; 1996; Jacobs, 2000; Domínguez-Rodrigo, 2002)
• However, the main characteristic of hunter-gatherer societies is the practice of subsistence hunting

Wong, K. (2014). Rise of the Human Predator. Scientific American, 310(4), pp.46–51. doi:https://doi.org/10.1038/scientificamerican0414-46.

This is another interesting article with quite a few points. It states that one theory is that " meat eating fostered self-control", arguing that whereas our closest species use anger and aggression to hunt humans use strategy, tools and community and in that sense hunting and eating meat is one of the very things that makes us a community based species. Also stating "Carnivory also would have radically changed the social dynamics among our ancestors, particularly once they began hunting larger prey that could be shared with other members of the group."

I mean if you want a statement that support humans as meat eaters how about: 

"It is hard to overstate the impact of Homo's shift to a meaty diet. Trends evident in the fossil and archaeological records indicate that it established a feedback loop in which access to calorie-packed food fueled brain growth, which led to the invention of technologies that permitted our ancestors to obtain even more meat (as well as high-quality plant foods), which in turn powered further expansion of gray matter. As a result, between two million and 200,000 years ago brain size swelled from roughly 600 cubic centimeters on average in the earliest representatives of Homo to around 1,300 cubic centimeters in Homo sapiens."