What Ear Infections Going Back 15,000 Years Tell Us About Human Health

But spike of ear infections in Chalcolithic could indicate that adding dairy to our diet gave us more than a calcium boost

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Natufian burial of woman with puppy
Natufian burial of woman with puppyCredit: Prof. Gonen Sharon, Tel Hai College

The agricultural revolution definitely changed human society everywhere it reached. After hundreds of thousands of years of subsisting on hunting and gathering in small groups, our ancestors began to settle down and cultivate food, albeit at different times in different places. From sporadic attempts starting over 20,000 years ago in what is today Israel to actual cultivation from about 12,000 to 10,000 years ago in the Levant and Turkey, farming took shape. Our diets gradually changed from sporadically gathered grasses and whatever animals we could spear or trap to specific grains plus meat from domesticated livestock — goats, then cows and sheep. In Europe, agriculture began to take on about 6,000 to 4,000 years ago.

One burning question is how this transition affected our health.

Now a new study published by Tel Aviv University scientists in the International Journal of Osteoarchaeology on ear infections in humans in Israel from the Natufian period 15,000 years ago through to the year 1917 C.E. (yes, a century ago) supports the theory that by and large, we did not in fact suffer from an increased disease burden - but we may have experienced changes in our health.

Many had assumed that we did become sicker with the advent of agriculture chiefly on the grounds that as we stopped chasing our dinner and roaming, and began eating wheat, barley and other grains, we became enfeebled (though mark you, farming especially without machinery is hard work); there was an unchecked assumption that diets became less diverse, depriving us of some nutrients; that once proudly footloose peoples suddenly began living in crowded conditions; and in inclement weather, they starved.

There is some truth in all of that but studies seeking to prove our deterioration as a rule have come up short. Now the study on the internal wall of the middle ear in people living in the Levant at different times throughout the last 15,000 years joins the pack.

If anything, after the Agricultural Revolution health actually improved, at least as far as middle ear infections were concerned, the team found.

Chalcolithic burial caveCredit: Israel Hershkovitz

They did detect a spike of ear infections in the Chalcolithic (aka the Copper Age), which began around the mid-fifth millennium B.C.E., and speculate that the advent of dairy may have been involved. Or change in the climate. Or both.

Prof. Hila May of the Sackler Faculty of Medicine at Tel Aviv University, who led the research, explains that their goal had been to test whether human health had actually deteriorated since the advent of farming, for which they needed a disease that was both prevalent and marked the bones. Influenza and the coronavirus do not leave signs on bones, for instance; chronic infection of the middle ear however does just that. Moreover, it’s extremely common, afflicting not only about 50 percent of human children but even plagued the Neanderthal, other studies have demonstrated.

Animals in the house

Drs. Katarina Floreanova, Efrat Gilat, Ilan Koren and Prof. Hila May of TAU analyzed bones gathered from archaeological sites for lesions of the middle ear indicative of chronic disease. They divided the bones into six periods: the Natufian (starting around 15,000 years ago, preceding the agricultural revolution, but marked by the start of permanent settlements); the pre-pottery Neolithic period (12,000 to 10,000 years ago), when proper agriculture began; the Chalcolithic, from 6,000 years ago, the Roman period from 2,000 years ago, the Byzantine period from 1,500 years ago, and the Ottoman period, ranging from 500 to 100 years ago.

Among the Natufian hunters-gatherers, almost 70 percent of individuals had ear infections. In the pre-pottery Neolithic that figure tumbled to 55 percent. A few thousand years later, in the Chalcolithic period, the numbers spiked again, with 80 percent afflicted; but then it fell again, to 50 percent, a level that persisted through the Roman period and to this day.

The researchers believe that the incidence of infection is related to the living conditions in each of these periods. The Natufian hunter-gatherers lived in crowded caves or huts; so did the first people to grow crops. Families huddled together in a small space, along with their animals and hearths, would have fouled the air inside, encouraging infection. One of the earliest known proper villages in the world, in Turkey, shows that the homes were built right on top of one another, as it were: very close together.

Chalcolithic remains, PekiinCredit: Ariel David

It bears adding that when swimming is left out of it, bacteria don’t usually cause ear infections directly: they usually result from upper respiratory tract diseases such as cold or flu. So when people lived in overcrowded spaces, disease can be expected to ensue.

As dwellings grew in size, animals were placed outdoors in a yard or pen, and the fire also moved outside; and the condition of their middle ears improved.

Why might ear infection have suddenly jumped in the Chalcolithic? May suggests two possible culprits, one being the cooler, wetter climate that was conducive to ear infections. The second cause might be that people started eating dairy.

Other studies have shown that dairying typically began hundreds or even thousands of years after the domestication of suitable animals such as the goat, sheep and cow; there are also indications that lactase persistence, an adult ability to digest milk, developed quite fast.

However, as dairy first entered the diet, it could have caused more than indigestion, bad breath and flatulence: it could have spurred more ear infection. 

At this point, May shares reservations about generalizing about the state of human health following the agricultural revolution.

Roman-era 1900-year-old inscription outs an unknown official: "The city of Dor honors Marcus Paccius...governor of the province of Judea"Credit: Jenny Carmel

In 2018 a separate group reported in Antiquity that the health of hunter-gatherers in prehistoric Vietnam was just as lousy as that of early farmers who lived a couple of thousand years later: The two groups suffered from different kinds of problems, but it cannot be said that one was clearly healthier than the other.

The truth is that it’s too simplistic to view human wellbeing in a binary way: “healthy” versus “not healthy”. That isn’t how our bodies work. And that isn’t how early farming worked either: the binary view of “hunter-gatherer” versus “farmer” is just as silly. The early farmers also hunted and gathered to supplement their diet and do so to this day, whether in the forest or the supermarket.

The whole point of studies like the new one by Floreanova et al is to provide nuance and paint part of the bigger picture, which it has done. Other studies have indicated that shifting to eating a lot of grain didn’t do well by our teeth. But now we know that our middle ear, for all the fuss in the Chalcolithic, survived the transition.