Ancestors
Some of our ancestors ate almost no meat
150g+Fiber per day in pre-agricultural samples
Neanderthals at El Sidrón left no meat in their dental plaque — only mushrooms, pine nuts, and moss. Other Neanderthals cooked plants: starches from dates, legumes, and grass seeds show heat damage in plaque from Iraq and Belgium. At Gesher Benot Ya‘aqov in Israel, about 780,000 years ago, hominins processed at least 55 food plants — nuts, fruits, seeds, tubers — and left starch on basalt hammers and anvils, the earliest clear evidence of plant-food processing. Fossilized stool samples from before agriculture show humans ate about 150 to 225 grams of fiber a day; most people today eat about 15. The pure meat-eating caveman is mostly a modern story. We do not have to harm or eat animals at all.
What the evidence says
The main points first. Every claim is tied to a source below.
Some Neanderthals ate no meat — the plaque shows it
Weyrich and colleagues sequenced DNA from dental plaque for a Nature paper. Belgian Neanderthals at Spy ate rhinoceros and sheep. Spanish Neanderthals at El Sidrón showed no meat — split-gill mushrooms, pine nuts, and forest moss. That does not mean the whole species was vegan. It does mean some people in a forest lived without a kill. A meat-only caveman story does not fit those teeth.
They cooked plants — the microscope found the starch
Henry, Brooks, and Piperno (PNAS 2011) recovered cooked starches from Neanderthal plaque in Iraq and Belgium: date palms, legumes, and grass seeds. Many grass-seed starches showed the damage pattern of cooking. A review across 17 sites found 61 plant taxa from 26 families used by Neanderthals — food, medicine, and more. Plants were in the mouth, heated on purpose — not a garnish on the side of a butcher shop.
Humans ate about 150–225 grams of fiber a day — most people now eat about 15
Leach and Sobolik measured prehistoric Chihuahuan Desert stool samples. Humans there ate on the order of 150–225 grams of fiber a day, including about 135 grams of inulin-type prebiotics from agave, sotol, mesquite, prickly pear, and onion. Coprolites from Mexico, Peru, and rural Africa tell a similar story: more than 100 grams a day, sometimes around 120. Eaton and Konner independently put late Paleolithic fiber around 100 grams a day or more. You cannot get those numbers from animal products. Fiber comes from plants.
780,000 years ago: 55 food plants — and tools to process them
Gesher Benot Ya‘aqov in Israel preserved nuts, fruits, seeds, vegetables, and tubers — 55 edible taxa — from Acheulean humans about 780,000 years ago. Later work found more than 650 starch grains on basalt hammers and anvils used to crack and crush plants: acorns, wild grasses, legumes, water-lily roots, water chestnuts. That is the earliest clear evidence of systematic plant-food processing. Early plant eating is not a side note. It is in the tools.
Oral bacteria adapted to starch early in Homo
Dental-plaque microbes from Neanderthals and modern humans share starch-binding adaptations that chimpanzees largely lack. The oral microbiome shifted with a starch-rich diet early in Homo — before Neanderthals and modern humans split. The mouth was already set up for plants.
Sources
Papers and datasets. Caveats stay on the card — small samples and single animals included on purpose.
Nature, 2017 · Small sample
No meat detected — El Sidrón Neanderthals
Weyrich et al. sequenced DNA in Neanderthal dental calculus. At Spy (Belgium), rhinoceros and sheep. At El Sidrón (Spain): no meat detected — mushrooms, pine nuts, forest moss. Small sample of individuals, not a species-wide rule. Those individuals were eating plants.
The Guardian · Review
El Sidrón: pine nuts, mushrooms, moss — Guardian
Accessible write-up of the Nature paper. Researchers were surprised not to find meat. Prior work had already suggested El Sidrón Neanderthals ate little meat. The plaque is the evidence.
PNAS, 2011 · Observational
Neanderthals cooked plants — Shanidar and Spy starches
Henry, Brooks, and Piperno (PNAS 2011): microfossils in calculus from Iraq and Belgium show date palms, legumes, and grass seeds, some chemically consistent with cooking. The idea of a ‘raw meat only’ Neanderthal does not match the microfossil evidence.
British Journal of Nutrition, 2010 · Observational
150–225 g of fiber a day — Chihuahuan Desert coprolites
Leach & Sobolik (British Journal of Nutrition, 2010): prehistoric northern Chihuahuan Desert coprolites imply humans ate ~150–225 g of fiber per day, with ~135 g of inulin-type prebiotics from agave, sotol, mesquite, prickly pear, onion. Modern U.S. intake is ~15 g. That is about ten times more plant fiber than a typical modern U.S. diet.
Paleo Foundation digest of coprolite studies · Review
Mexico, Peru, and rural Africa — also over 100 grams
Coprolites from Ocampo Caves and Tehuacán in Mexico and Huaca Prieta in Peru point to fiber intakes over 100 grams a day. Rural African coprolite work has been read as high as about 120 grams of prebiotic fiber a day. Different continents. Same order of magnitude. Plants were the bulk of the stool because they were the bulk of the diet.
NEJM / Eaton & Konner · Review
Paleolithic nutrition — plants, fiber, vitamin C
Eaton & Konner’s original reconstruction (NEJM 1985 / 1997 revisit): late Paleolithic diets ~65% plant-derived, fiber often exceeding 100 g/day, vitamin C on the order of ~392 mg — amounts that a meat-only diet cannot provide.
European Journal of Clinical Nutrition, 2006 · Review
Eaton 2006: ancestral fiber perhaps 100 grams a day
Boyd Eaton: ancestral fibre consumption was high, perhaps 100 g/day. Vitamin, mineral, and phytochemical intakes were typically several times modern levels. Those numbers only work on a plant-heavy plate.
Nutrition in Clinical Practice, 2010 · Review
Konner & Eaton, 25 years later — still a high-fiber ancestral diet
Konner and Eaton, 2010: the Paleolithic nutrition model still has humans eating far more fiber than a modern Western diet. The 1985 reconstruction put ancestral fiber well above 100 grams. The update did not walk that back.
PNAS, 2016 · Observational
55 food plants, 780,000 years ago — Gesher Benot Ya‘aqov
Melamed et al. (PNAS 2016): an Acheulean site in Israel preserved 55 edible plant taxa — nuts, fruits, seeds, vegetables, underground storage organs. Homo erectus-grade humans were already eating a wide range of plants.
PNAS, 2025 · Observational
Starch on hammers and anvils — 780,000 years ago
Ahituv et al. (PNAS 2025): more than 650 starch grains on basalt percussive tools at Gesher Benot Ya‘aqov — acorns, grasses, legumes, water-lily roots, water chestnuts. Earliest clear evidence of systematic plant-food processing.
Evidence for the Paleoethnobotany of the Neanderthal · Review
Neanderthal plant use across 17 sites
A review of the paleoethnobotany of Neanderthals found 61 plant taxa from 26 families at 17 archaeological sites — food, medicine, and more. Plant exploitation was widespread, not a southern exception.
PNAS, 2021 · Observational
Oral microbes adapted to starch in Homo
Fellows Yates et al. (PNAS 2021): Neanderthal and modern-human oral streptococci share amylase-binding adaptations largely absent in chimpanzees, pointing to starch-rich foods early in Homo, before the split.
PNAS / Sponheimer et al., 2013 · Observational
Early hominins ate C3 plants
Carbon isotopes: prior to ~3.5 million years ago, early hominins ate almost exclusively C3 plants (trees, shrubs, herbs — the diet of apes). The dietary shift was a widening of plant foods, not simply a turn to hunting.