The analysis of the content and use of prehistoric vessels has become a valuable source of information on the food patterns and subsistence practices of past societies. A research conducted on the materials found at the Huescan sites of Cueva de Chaves (Bastaràs), at 640 metres above sea level, and at Espluga de la Puyascada (La Fueva), at 1,300 metres above sea level, in a strictly Pyrenean mountain region, now has yielded the first direct evidence of dairy product consumption and processing in the Pyrenees during the earliest stages of the Neolithic.

The study was conducted by prehistorians from the Universitat Autònoma de Barcelona (UAB) and the University of Zaragoza, and chemists from the University of Strasbourg, France, on materials on display at the Huesca Museum. The findings have now been published in the journal Archaeological and Anthropological Sciences.

The research was conducted through a combination of techniques used to identify organic residues and the isotopic characterisation of fatty acids to determine animal origin, as well as data obtained of the morphology and functionality of ceramics and the archaeozoological studies of both sites.

The analysis of organic residues preserved in the argillaceous matrix of the interior of 36 ceramic vessels indicates that 7,500 years ago dairy products were already processed and consumed in the Central Pyrenees. The correlation between the residues of dairy fats and the different forms of the pottery suggests, moreover, that all the processes (preparation, consumption and storage) were carried out in both settlements.

This “questions previous considerations in which dairy consumption in the Pyrenees was thought to have begun much later,” points out Nàdia Tarifa, researcher from the University of Strasbourg when this study was conducted, and lead autor of the paper. “It was always thought that prehistoric social dynamics in mountainous regions were slower or ‘less evolved’ than in coastal regions. Our study adds solid proof to previous faunistic studies conducted in both sites, which had pointed to dairy farming in these mountainous regions at the very early stages of the Neolithic period,” Tarifa states.

The study also shows how pig-derived products may have been processed or stored in ceramic vessels at both sites, which would indicate the importance of this species for the early mountain farming economies. In contrast to the results for milk, researchers also observed variations between the two sites in terms of the exploitation of meat from ruminants and pigs, with a predominance of the former in Espluga de la Puyascada and the latter in Cueva de Chaves. These differences could be related to the characteristics of the settlements and their surroundings, and to the methods of meat processing.

The researchers also identified residues from processed vegetables, as well as from pine resin. The latter substance would have been used to waterproof the inside of the vessels.

The results support the idea that in the early Neolithic period in the Pyrenean area there was a mixed economy based on integrated agriculture and livestock farming (in which one supported the other), with sheep herds as the main source of meat and milk.

“Our findings provide a better understanding of consumption habits and the technological use of resources in the early Neolithic period in the Pyrenees and open up new avenues of research to deepen our understanding of the social and economic dynamics of ancient societies, especially in mountainous areas,” says Alejandro Sierra, researcher at the UAB and co-author of the study.

The study found that in animals, a high-fat diet disrupts resident gut bacteria, alters behavior and, through a complex pathway connecting the gut to the brain, influences brain chemicals in ways that fuel anxiety.

“Everyone knows that these are not healthy foods, but we tend to think about them strictly in terms of a little weight gain,” said lead author Christopher Lowry, a professor of integrative physiology at CU Boulder. “If you understand that they also impact your brain in a way that can promote anxiety, that makes the stakes even higher.”

Lowry’s team divided adolescent rats into two groups: Half got a standard diet of about 11% fat for nine weeks; the others got a high-fat diet of 45% fat, consisting mostly of saturated fat from animal products.

The typical American diet is about 36% fat, according to the Centers for Disease Control and Prevention.

Throughout the study, the researchers collected fecal samples and assessed the animals’ microbiome, or gut bacteria. After nine weeks, the animals underwent behavioral tests.

When compared to the control group, the group eating a high-fat diet, not surprisingly, gained weight. But the animals also showed significantly less diversity of gut bacteria. Generally speaking, more bacterial diversity is associated with better health, Lowry explained. They also hosted far more of a category of bacteria called Firmicutes and less of a category called Bacteroidetes. A higher Firmicutes to Bacteroidetes ratio has been associated with the typical industrialized diet and with obesity.

The high-fat diet group also showed higher expression of three genes (tph2, htr1a, and slc6a4) involved in production and signaling of the neurotransmitter serotonin — particularly in a region of the brainstem known as the dorsal raphe nucleus cDRD, which is associated with stress and anxiety.

While serotonin is often billed as a “feel-good brain chemical,” Lowry notes that certain subsets of serotonin neurons can, when activated, prompt anxiety-like responses in animals. Notably, heightened expression of tph2, or tryptophan hydroxylase, in the cDRD has been associated with mood disorders and suicide risk in humans.

“To think that just a high-fat diet could alter expression of these genes in the brain is extraordinary,” said Lowry. “The high-fat group essentially had the molecular signature of a high anxiety state in their brain.”

Lowry suspects that an unhealthy microbiome compromises the gut lining, enabling bacteria to slip into the body’s circulation and communicate with the brain via the vagus nerve, a pathway from the gastrointestinal tract to the brain.

“If you think about human evolution, it makes sense,” Lowry said. “We are hard-wired to really notice things that make us sick so we can avoid those things in the future.”

Lowry stresses that not all fats are bad, and that healthy fats like those found in fish, olive oil, nuts and seeds can be anti-inflammatory and good for the brain.

His advice: Eat as many different kinds of fruits and vegetables as possible, add fermented foods to your diet to support a healthy microbiome and lay off the pizza and fries. Also, if you do have a hamburger, add a slice of avocado. Some research shows that good fat can counteract some of the bad.