Neandertal self-medication

Karen Hardy and colleagues (2013) have a brief paper in a recent issue of Antiquity putting into context their recent finding about possible medicinal plant use by Neandertals. In 2012, this team of authors reported on their examination of the dental calculus of the El Sidrón Neandertals. They found some evidence for plant food consumption, in line with results from other Neandertal sites. But additionally they found chemical traces of other interesting things:

  1. Evidence of oil shale or bitumen. Bitumen was used by Neandertals at other sites as an adhesive for hafting stone points onto wooden spears or handles. That evidence came from the stone points themselves, so it is possible that bitumen was used more widely as an adhesive or preservative in contexts that do not persist as long in the archaeological record.

  2. Alkyl phenols and polynuclear aromatic hydrocarbons consistent with exposure to wood smoke or smoked food.

  3. Chemical residues consistent with consumption of yarrow and chamomile, including bitter-tasting and appetite-suppressing compounds.

  4. A very low level of proteins and absence of lipid components suggested that the diet of these individuals was protein-poor during the time they were forming calculus.

They reinforced conclusions about cooking plant foods by Neandertals, based on both the chemical evidence and the examination of starch granules embedded in the calculus:

Using mass spectrometry, we have identified the ingestion of cooked carbohydrates in the calculus of two adults, one adult in particular having apparently eaten several different carbohydrate-rich foods. The evidence for cooked carbohydrates is confirmed both by the cracked/roasted starch granules observed microscopically and the molecular evidence for cooking and exposure to wood smoke or smoked food in the form of methyl esters, phenols, and polynuclear aromatic hydrocarbons (notably pyrene and fluoranthene) found in the dental calculus.

The more intriguing observation was the yarrow and chamomile consumption. Hardy and colleagues considered it likely that these plants were used for medicinal purposes by the Neandertals. They discuss the botanical qualities of these plants briefly in their current paper (2013):

Yarrow is a flowering plant in the Asteraceae family, common across temperate regions. It was used as a vegetable in the Middle Ages, notably as a component of soup, but has an extended history of medicinal use, in particular as an astringent (Chandler et al. 1982). Camomile tea is well-known today as an aid for stomach complaints and nervousness, though there is little record of it as a food. Bioactive constituents are linked to antimicrobial and anti-inflammatory properties (McKay & Blumberg 2006), while its ability to assist with general anxiety disorder has been demonstrated (Jay et al. 2009).

Laura Buck and Chris Stringer (2013) suggested an alternative explanation for the yarrow and chamomile. They note that arctic peoples often eat the stomach contents of animals they eat, which comprises one of the major sources of plant foods in their diet. In such cases, the plants are not necessarily those most palatable or digestible by humans.

We are not, of course, proposing that Neanderthals would not have eaten plant foods, nor are we discounting the possibility of Neanderthal self-medication. However we suggest that, given the evidence for widespread consumption of stomach contents in recent human groups, and the likely benefits of a rich source of vitamin C and carbohydrates (to say nothing of the possible cultural or social reasons for chyme consumption) this behaviour should be taken into account as a possible source of plant foods, including ‘medicinal’ ones, in the archaeological and fossil record.

Hardy and colleagues (2013) do not directly react to this argument (which may have emerged after submission of the article), but they do note that the El Sidrón Neandertals lived during a time of relatively mild climate when plant foods would have been easily available in the immediate surroundings. The evidence for cooked starch granules and paucity of protein further suggest that the plants were selected and used by the Neandertals rather than opportunistically consumed as part of herbivore stomach contents.

But these possibilities are not mutually exclusive, either. From my point of view, one of the most likely ways that Neandertals may have accomplished the gelatinization of starches is by cooking grains and other plants inside of animal bladders, including the stomach.

We may also consider that both yarrow and chamomile are used for dying fabrics, so it is not impossible that the Neandertals were processing them as pigments by chewing them. They are already known to have used red earth pigments and black manganese pigments.

Hardy and colleagues finish their 2013 paper by considering what self-medication would mean for our understanding of Neandertal behavior:

Though all primates (and other animals) have varying levels of enzymes which make us more or less tolerant of certain toxins, there are plants which are poisonous to all; in order to survive, hominins needed to know which plants not to eat and how and when to eat those plants they selected. The use of edible bitter tasting plants by the Neanderthals of El Sidrón suggests their knowledge was sufficiently refined to use plants with confidence even when their bitter taste warned of potential toxicity. This demonstrates that their knowledge of plants was at least equal to today’s higher primates; with their additional linguistic and technological abilities it may have been far more elaborate. Rather than contradicting the extensive evidence for consumption of meat, the evidence for the use of plants adds a rich new dimension to our developing knowledge of Neanderthal life. We can never know for sure why yarrow and camomile were ingested at El Sidrón, but we propose that the evidence for self-medication offers the most convincing behavioural context.

An aside: I know there are anthropologists who will take in this evidence of interesting Neandertal behavior and argue they had a specific “module” in their mind that facilitated naturalistic knowledge, while simultaneously arguing they lacked some crucial “module” enabling modern human social behavior.

That’s special pleading. We do not need to hypothesize that Neandertals had a multicameral mind to explain that their cultures were different from ours. Cultures do not weigh every kind of activity or knowledge equally or enable them to be learned equally easily.


Buck, L. T., & Stringer, C. B. (2013). Having the stomach for it: a contribution to Neanderthal diets?. Quaternary Science Reviews. (in press) doi:10.1016/j.quascirev.2013.09.003

Hardy, K., Buckley, S., & Huffman, M. (2013). Neanderthal self-medication in context. Antiquity 87 (2013): 873–878. URL:

Hardy, K., Buckley, S., Collins, M. J., Estalrrich, A., Brothwell, D., Copeland, L., ... & Rosas, A. (2012). Neanderthal medics? Evidence for food, cooking, and medicinal plants entrapped in dental calculus. Naturwissenschaften, 99(8), 617-626.