Thread by @RootCauseDoctor

[EVOLUTION OF THE HUMAN TROPHIC LEVEL DURING THE PLEISTOCENE]

by @bendormiki @raphaels7

A fascinating article that lays out the evidence for humans as high-level CARNIVORES 🍖🥩

Some highlights 👇

Using data from:
- human physiology and genetics
- archaeology
- paleontology
- zoology

The authors give us an insight into the evolved human trophic level, or our 'position on the food chain'.

en.wikipedia.org/wiki/Trophic_l…

"The evidence shows that the trophic level of the Homo lineage that most probably led to modern humans evolved from a low base to a high, carnivorous position during the Pleistocene, beginning with Homo habilis and peaking in Homo erectus....

...a reversal of that trend appears in the Upper Paleolithic, strengthening in the Mesolithic/Epipaleolithic and Neolithic, and culminating with the advent of agriculture."

Lets take a look at the evidence:

BIO-ENERGETICS

Humans had high energetic requirements for a given body mass and a shorter time during the day to acquire and consume food.

Hunting provides tenfold higher energetic return per hour compared to plants...

DIET QUALITY

In primates, a larger brain is associated with high energy density food. With the largest brain among primates, humans are likely to have targeted the highest density food, animal fats, and proteins.

Brain size declined during the terminal Pleistocene, and subsequent Holocene. Diet quality declined at the same time with the increased consumption of plants.

HIGHER FAT RESERVES

With much higher body fat reserves than primates, humans are uniquely adapted to lengthy fasting. This adaptation may have helped with overcoming the erratic encountering of large prey.

GENETIC ADAPTATIONS TO HIGH-FAT DIET

Humans adapted to higher fat diets, presumably from animals. Evidence suggests humans shut down regions of the genome to accommodate a high-fat diet while chimpanzees open regions of the genome to accommodate a high sugar diet...

STOMACH ACIDITY

Higher stomach acidity is found in carnivores to fight meat-borne pathogens. Humans' stomach acidity is even higher than in carnivores, equaling that of scavengers.

Adaptation may have evolved to allow large animals' consumption in a central place over days and weeks with pathogen build-up.

GUT MORPHOLOGY

Humans' gut morphology and relative size are radically different from chimpanzees' gut. Longer small intestines and shorter large intestines are typical of carnivores' gut morphology and limit humans' ability to extract energy from plants' fiber.

MASTICATION

Reduction of the masticatory system size already in Homo erectus, compared to early hominins, who relied on terrestrial vegetation as a food source. The reduced size is compatible with meat and fat consumption.

AGE AT WEANING

Carnivores wean at a younger age, as do humans. Early weaning “highlight the emergence of carnivory as a process fundamentally determining human evolution”

VITAMINS

Hypothesis for required nutritional diversity to supply vitamins is contested. It appears that all vitamins, including vitamin C are supplied in adequate quantities on a carnivorous diet.

TARGETING FAT

Humans concentrated on hunting fatty animals at substantial energetic costs. They preferentially brought fatty parts to base camps, hunted fattier prime adults, and exploited bone fat.

STABLE ISOTOPES

Nitrogen 15N isotope measurement of human fossil collagen residues is the most used method for determining trophic level in the last 50k years.

All studies show that humans were highly carnivorous until very late, before the appearance of agriculture.

DENTAL PATHOLOGY

Dental caries, evidence of substantial consumption of carbohydrates, appeared only some 15 thousand years ago in groups with evidence of high plant food consumption.

BEHAVIORAL ADAPTATIONS

A comparison of humans' behavior patterns with chimpanzees and social carnivores found that humans have carnivore-like behavior patterns.

Food sharing, alloparenting, labor division, and social flexibility are among the shared carnivorous behaviors.

PALEONTOLOGICAL EVIDENCE

Extinctions of large herbivores were associated with humans' presence in Africa and arrival to continents and islands, such as Australia and America, suggesting preferential hunting of large prey.

CONCLUSION

The authors conclude:

"Thus, we can present a hypothesis for the evolution of the human trophic level during the Paleolithic whereby consumption of animal-sourced food increased with early Homo and peaked in Homo erectus...

...Homo erectus was morphologically and behaviorally adapted to carnivory, was a social hunter of megafauna, possibly specializing in large prey, which, by zoological analogy, would have been a hypercarnivore with some 70% of the diet derived from animals."

IMPLICATIONS (by yours truly)

• Human’s hunter-gatherer evolutionary niche was intensely carnivorous, and adaptations to a more omnivorous diet happened later, through necessity, when opportunity to hunt megafauna disappeared.

• Plant foods provide energy in the absence of animal fat, but are inferior in both energy density and nutrient bio-availability.

• Plant agriculture was an innovation by necessity, and practiced in its current form produces nutrient-depleted food.

• A heavily animal-based diet appears to be evolutionarily appropriate and a winning strategy for taking back your health (h/t @CarnivoreMD).

• Ruminant cattle (beef, bison, etc) are the most accessible substitute for ancestral megafauna foods.

ACTIONABLE ADVICE I

- avoid all processed/packaged foods – seed oils, carbs, sugar. These were absent in our evolutionary past and are historical abominations.

- develop metabolic flexibility by periodic nutritional ketosis by fasting, lifting and heavy animal food consumption.

ACTIONABLE ADVICE II

- focus on high quality animal fats for their essential micro-nutrient content, especially during developmental growth of infancy, childhood and adolescence.

- buy organic/regenerative animal foods wherever possible.

And finally, read the complete article here:

onlinelibrary.wiley.com/doi/10.1002/aj…

Or watch @bendormiki present these ideas in talk form:

Also, check out my previous thread where I cover the implications of removing humans from our evolutionary niche:



@SBakerMD @KenDBerryMD @FructoseNo @SolBrah @drcateshanahan

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