I am treating "human diet" as the diet of the human lineage: primate ancestors -> early hominins -> genus Homo -> Homo sapiens -> modern industrial humans.
Important caveat: herbivore/carnivore/omnivore is too blunt for this topic. The best evidence says the lineage is overwhelmingly omnivorous, but with strong plant-heavy and animal-heavy phases. So this gives a forced classification plus the more honest lean.
| Period | Rough date | What the diet probably looked like | Forced class |
|---|---|---|---|
| Early primate / ape ancestors | ~65-7 million years ago | Mostly fruits, leaves, seeds, flowers, gums, insects, small animals when available. Think flexible forest omnivory, not a cow-like herbivore. | Omnivore, plant-heavy |
| Human-chimp last-common-ancestor zone | ~7-6 Ma | No direct fossil diet, but living apes imply fruit-heavy omnivory: lots of plant foods, some insects/eggs/small vertebrates. | Omnivore, plant-heavy |
Earliest hominins: Sahelanthropus, Orrorin, Ardipithecus |
~7-4.4 Ma | Likely woodland foods: fruits, leaves, nuts, tubers/roots, insects, maybe occasional meat. Ardipithecus ramidus is usually reconstructed as generalized/omnivorous, not grassland hunter. |
Omnivore, plant-heavy |
Early Australopithecus |
~4.2-3 Ma | Mostly plant foods, but broader than apes: C3 forest foods plus increasing C4/CAM resources in some populations, meaning grasses/sedges/tubers or animals that ate them. | Omnivore, plant-heavy |
Later Australopithecus |
~3-2 Ma | Still mostly plant-based. New 2025 enamel nitrogen evidence from Sterkfontein argues Australopithecus did not regularly eat mammalian meat. But insects/eggs/occasional animal foods remain plausible. |
Omnivore, near-herbivore lean |
Paranthropus side branch |
~2.7-1.2 Ma | Not our direct line, but useful contrast. Robust jaws once made people think "nuts/seeds"; isotope work suggests especially P. boisei ate lots of C4 plants: grasses/sedges/underground plant parts. |
Herbivore-ish / plant-heavy omnivore |
Earliest Homo, Oldowan tool users |
~2.8-1.8 Ma | Major shift: more meat, marrow, scavenging/hunting, stone-tool butchery. Well-accepted butchered bones around 2.6 Ma; more persistent carnivory around ~2.0 Ma. Still not pure carnivore: gathered plants, tubers, fruit, honey/insects likely mattered. | Omnivore, animal intake rising |
Homo erectus / early Pleistocene Homo |
~1.9 Ma-400 ka | Bigger bodies/brains, smaller teeth/guts relative to earlier hominins, more large-animal exploitation, marrow/fat, likely cooking/fire later in this span. Some recent models argue Homo became high-trophic/hypercarnivorous for much of the Pleistocene. I would call that animal-heavy omnivory, not strict carnivory. | Omnivore, carnivore-leaning |
| Fire and cooking become important | maybe ~1.8 Ma opportunistic fire; strong cooking evidence by ~780 ka | Fire changes the diet: cooked tubers, cooked meat/fish, safer foods, more calories per chewing hour. New Wonderwerk evidence pushes repeated fire use possibly to 1.07-1.79 Ma, but not necessarily cooking. The clearest early cooking evidence is cooked fish at Gesher Benot Ya'aqov ~780 ka. | Omnivore, cooked-food adapted |
| Neanderthals / archaic humans | ~400-40 ka | In cold Ice Age Europe, isotope evidence often puts Neanderthals very high on the food chain: large herbivore meat/fat was huge. But dental calculus and other evidence show plants too: starches, legumes, nuts, tubers, dates, wild grains depending on region. | Omnivore, often carnivore-leaning |
Early Homo sapiens hunter-gatherers |
~300-50 ka | Extremely flexible. African and coastal groups used meat, fish, shellfish, tubers, fruit, nuts, seeds, honey. No single "ancestral human diet." Geography dominates. | Omnivore |
| Upper Paleolithic / Late Stone Age | ~50-12 ka | Big-game hunting in many places, but also broadening diets: fish, birds, shellfish, small mammals, nuts, seeds, wild cereals, roots. Morocco's Taforalt people ~15-13 ka show surprisingly high plant reliance while still eating animals. | Omnivore, regionally variable |
| Mesolithic / Epipaleolithic broad-spectrum foragers | ~15-8 ka | As Ice Age conditions ended, many groups diversified hard: fish, shellfish, birds, small game, wild grains, nuts, tubers. Some groups were meat/fish-heavy; others were plant-heavy. | Omnivore |
| Neolithic agriculture begins | ~12-5 ka | Big shift from wild-food omnivory to domesticated staples. Wheat/barley/lentils/peas in the Fertile Crescent; rice/millet in parts of Asia; maize/squash/beans in the Americas; yams/taro/bananas elsewhere. Meat persists, but many diets become cereal- and legume-heavy. | Omnivore, plant-staple-heavy |
| Pastoralism and dairying | ~10 ka-present, varies by region | Milk, yogurt, cheese, blood/meat in herding societies. Lactase persistence evolves recently and unevenly, strongly tied to dairying cultures. | Omnivore, pastoral variants |
| Bronze/Iron/Classical agrarian societies | ~5 ka-1.5 ka | Most people: grains + pulses + vegetables + fermented foods + small amounts of meat/fish/dairy when available. Elites had more meat, wine, spices, sweets. | Omnivore, grain-heavy |
| Medieval to early modern | ~1.5 ka-250 years ago | Still mostly agrarian. Staples dominate: rice, wheat, barley, millet, maize, potatoes after Columbian exchange, lentils/beans, seasonal vegetables. Meat varied massively by class/ecology/religion. | Omnivore, plant-staple-heavy |
| Industrial modern diet | ~1750-1950 | Milling, sugar, refined flour, canned foods, industrial oils, global trade, refrigeration. More consistent calories for many, more refined carbs/fats, more meat in rich countries. | Omnivore, increasingly processed |
| Contemporary global diet | ~1950-2026 | Wild variability: vegan, vegetarian, grain-heavy, meat-heavy, fast-food-heavy, traditional mixed diets. Global nutrition transition: more animal-source foods, refined grains, sugar, oils, packaged/ultra-processed foods. In the US, CDC data for Aug 2021-Aug 2023 says ultra-processed foods were ~53% of adult calories and ~61.9% of youth calories. | Omnivore, industrially processed |
If you force the whole lineage into only three buckets:
Homo: mostly plant-heavy omnivore, sometimes close to herbivore in practice.Homo: omnivore with rising animal food intake, sometimes strongly carnivore-leaning, especially in Pleistocene/cold environments.Homo sapiens: extreme omnivore generalist. We are not biologically locked into one ancestral diet. We are the "eat whatever the ecology + culture + tools make possible" species.My classification by strict biology: humans are omnivores, always. The honest historical story is not herbivore -> carnivore -> omnivore. It is more like:
plant-heavy ape omnivore
-> broader hominin omnivore
-> animal-heavy Homo omnivore in many Pleistocene settings
-> flexible hunter-gatherer omnivore
-> grain-heavy agricultural omnivore
-> processed industrial omnivore
[S1] Briana Pobiner, Nature Education / Smithsonian - Evidence for Meat-Eating by Early Humans
https://www.nature.com/scitable/knowledge/library/evidence-for-meat-eating-by-early-humans-103874273/
[S2] Sponheimer et al., PNAS 2013 - Isotopic evidence of early hominin diets
https://pmc.ncbi.nlm.nih.gov/articles/PMC3696771/
[S3] Ludecke et al., Science 2025 - Australopithecus at Sterkfontein did not consume substantial mammalian meat
https://www.science.org/doi/10.1126/science.adq7315
[S4] Lee-Thorp et al., PNAS 2012 - Early shift to C4 resources by Pliocene hominins
https://www.pnas.org/doi/10.1073/pnas.1204209109
[S5] Smithsonian Human Origins - Ardipithecus ramidus species page
https://humanorigins.si.edu/evidence/human-fossils/species/ardipithecus-ramidus
[S6] Ben-Dor et al., American Journal of Physical Anthropology 2021 - Evolution of the human trophic level during the Pleistocene
https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.24247
[S7] Marin-Monfort et al., PLOS ONE 2026 - Early Pleistocene use of fire at Wonderwerk Cave
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0347480
[S8] Zohar et al., Nature Ecology & Evolution 2022 - Evidence for cooking fish 780,000 years ago
https://www.nature.com/articles/s41559-022-01910-z
[S9] Henry, Brooks & Piperno, PNAS 2011 - Neanderthal plant microfossils in dental calculus
https://pmc.ncbi.nlm.nih.gov/articles/PMC3021051/
[S10] Jaouen et al., PNAS 2019 - High nitrogen values / Neanderthal high trophic position
https://www.pnas.org/doi/10.1073/pnas.1814087116
[S11] Moubtahij et al., Nature Ecology & Evolution 2024 - Taforalt hunter-gatherers' high plant reliance
https://www.nature.com/articles/s41559-024-02382-z
[S12] Chen et al., PLOS ONE 2024 - Plant-dominant early foragers on the Andean Altiplano
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0296420
[S13] Lieberman et al., American Journal of Clinical Nutrition 2023 - Measured variation among tropical hunter-gatherer diets
https://pubmed.ncbi.nlm.nih.gov/37343704/
[S14] National Geographic - Development of agriculture
https://education.nationalgeographic.org/resource/development-agriculture/
[S15] Gerbault et al., Philosophical Transactions B 2011 - Evolution of lactase persistence
https://pmc.ncbi.nlm.nih.gov/articles/PMC3048992/
[S16] FAO - Structural transformation and the nutrition transition
https://www.fao.org/3/cd2144en/online/state-of-agricultural-commodity-markets/2024/structural-transformation-nutrition-transition.html
[S17] CDC/NCHS Data Brief 536, 2025 - Ultra-processed food consumption in youth and adults, US 2021-2023
https://www.cdc.gov/nchs/products/databriefs/db536.htm