Anthropology.net

Razib has chimed in on the latest piece of research to come from John Lukacs, “Fertility and Agriculture Accentuate Sex Differences in Dental Caries Rates,” published in Current Anthropology. Throughout time, women have had more cavities on average than men. I’ve explained how cavities are formed in a previous post.  Diet change and sexual division of labor have been suggested to be the dominant forces at play. With the Neolithic revolution, the human diet and lifestyle was dramatically revamped. With steady food sources, people reproduced faster and populations boomed.

Lukacs did a comprehensive review of records of the frequencies of dental cavities in both prehistoric and living human populations in his paper. His sample included teeth from people of Euro-American ancestry, and from Africa, teeth from Guinea-Bissau, Madagascar, and Niger… from Asia, he covered China and Taiwanese aboriginals.

He concluded that the increased sedentary lifestyle and fertility increased the demands on the female reproductive system, which in turn intensified the negative impacts of dietary change on oral health. of women He attributes the increased rates of dental caries in females to three factors:

• Female sex hormones, like estrogen, significantly impact cavity formation. Estrogen is produced by the placenta throughout a pregnancy and the levels increase steadily until birth.
• Females produce less saliva than men. Saliva has two important components, enzymes like amylase, that begin break down of complex sugars. If these sugars aren’t broken down, microbes in the mouth consume them and as a biproduct release acids that break down the enamel of the tooth. Saliva also has another component, antibodies and phagocytes that attack the very microbes that cause cavities.
• Women crave high-energy, sweet foods during the third trimester which we all know are promotes cavities and dental decay.

So ultimately female physiology combined with the the changes in diet and increased feritlity are the reasons why women have more cavities than men. Razib mentions that with increased fertility comes a reciprocal increase infant mortality, especially because the agricultural revolution increased communicable diseases. He concludes that hunter-gatherer infants are far more likely to reach reproductive age than infants of an agriculturalist.

But I disagree. Despite the recent popularity of the paleo-diet, the real hunter gatherer lifestyle is not easy. Many hunter gatherer societies have erratic sources of nutrition, very few have regular caloric intakes. John Hawks explained that among hunter gatherers, like the Hiwi, only 43% of the adults were expected to see the age of 30. Furthermore, many hunter gatherer cultures also have food taboos which dictate the diets of females. For example, Australian aboriginal societies restrict protein and fat foods for pregnant and lactating women. Similar traditions exist in Africa too. In Athapaskan societies, females at menarche cannot eat fresh meat.

Women who do not consume many calories, reach menarche at an older age and become amenorrheic — irregularly menstruate. If and when they do have a child, they are often of low birth weight, and the child has a higher risk of dying because they have little to no fat reserves. They consume inadequate amounts of nutrition since the mothers cannot make insufficient amounts of milk. All of which influences birth spacing significantly.

Despite the increased probability of cavities, the Neolithic revolution has generally been a good thing for women and children.

John R. Lukacs (2008). Fertility and Agriculture Accentuate Sex Differences in Dental Caries Rates Current Anthropology, 49 (5), 901-914 DOI: 10.1086/592111

Okay, I got some really cool archaeology news to share with you. In fact it is so cool that I’m staying up to write up my review. Before I get into it, let me first introduce some relative background you’ll need to understand.

One of the most important predecessors to the Inca Empire were the Tiwanaku, a pre-Columbian culture that expanded from a home base on the south eastern edge of Lake Titicac, Bolivia to what is now southern Peru and northern Chile. The expansion happened between 1,500 years ago to 1,000 years ago and is commonly referred to as the Middle Horizon of Andean prehistory.

The Tiwanaku perfected a type of agriculture which raised crops from the ground. Lowered canals innervated the mound-like crops, and during the day, the crops absorbed water and canals absorbed solar radiation. During chilly nights, the heat radiated into the soil, preventing crops from freezing. The warmed canals also served a secondary function: providing a water source to farm edible fish.

Aside from their unique achievements in agriculture, the Tiwanaku also had an equally curious architectural style, employing massive ashlar blocks sometimes as heavy as 130 tons quarried 40km away. They built temples and platforms as large as 200 meters on each side and 15 meters tall. According to some hand-me-down stories, myths passed down to the Incas and then to the Spanish, these buildings served as spiritual centers. Fittingly, structures like the Gateway of the Sun have representations of their main deity, Viracocha. Other statues represent other deities, sometimes even abstract representations of a calendar and religious purposes.

An Example of a Tiwanakuan Snuff Kit

Tiwanaku burials continue this spiritual motif. Many mummies and skeletons from this culture also include tablets and snuff kits documenting the use of psychoactive drugs perhaps in a spiritual afterlife ritual or shamanistic tradition. In fact an archaeologist reported 614 snuffing kits recovered from an excavation, which suggests that the Tiwanaku were possibly using hallucinogenic materials. Previous chemical analysis of the kits indicated that they once held Vilca  (Anadenanthera colubrina), a plant rich in hallucinogenic tryptaminic alkaloids. Ethnographers have documented consumption of Vilca or hatáj by Wichi shamans. CAT scans of Tiwanakuan skulls have shown signs of chronic perinasal damage in some cases, likely caused by frequent sniffing of Anadenanthera. But we haven’t, as of yet, proven that the Tiwanaku consumed these drugs.

And here’s where a new paper in the Journal of Archaeological Science comes thru. The paper, “Identification of psychoactive alkaloids in ancient Andean human hair by Gas Chromatography/Mass Spectrometry ,” involves an analysis of the chemical composition of hairs from 32 mummies from northern Chile, dating to the Tiwanakuan expansion. The hairs were removed then cleaned and alkaloids were extracted from them. The alkaloids were loaded in a gas chromatographer, a device that separates molecules into compounds based upon how they move about through a stationary phase. Every compound has a specific retention time in the stationary phase, which ultimately is detected by a scaled down mass spectrometer. The mass spec gives a mass to charge ratio for every compound and this is all assembled to build the unique chemical fingerprint of a molecule.

The authors’ methodology seems sound. They duplicated some trials if they had extra material, even did triplicates when they had a lot more hair lying around. They also calculated the lowest detectable amount of alkaloid, just to determine the limits of accuracy. And for one more precautionary move, they also looked at modern day samples as well, to see if there’s something in the air or water that’s being inadvertently absorbed.

They specifically looked to find fingerprints of harmine and 5-methoxy-N,N-dimethyltryptamine. I don’t know what 5-methoxy-N,N-dimethyltryptamine does. It is found in Anadenanthera colubrina, so I assume it is a psychoactive drug… If any pharmacologists, physicians, chemists, neurologists, etc. out there know its affects please let me know in the comments below. But I do know what harmine does. It ultimately inhibits the break down of neurotransmitters, like serotonin and dopamine, giving the consumer more prolonged effects of abundant neurostimulus.

The results suggest that none of the mummies tested positive for 5-methoxy-N,N-dimethyltryptamine alkaloid, which is highly controversial considering lots of snuffing kits test positive for this chemical. The results also showed that two of the mummies tested positive for harmine. The first harmine using individual was buried with drug paraphernalia, but did not have lesions. In fact he has a snuffing tablet, one four points hat and the remainders of another one, and several pan pipes. The hat indicates the individual was of significant social prestige. CAT scans of his skull show that he had sclerotic lesion in the perinasal area — perhaps a chronic sniffer. The other individual was a 1 year old infant, buried with also with tablet and a four points Tiwanaku hat. It is highly unlikely that we had a 1 year old drug addict — but perhaps drug consumption was part of the ceremonial processes either during the life of this child or immediately after?

Since only 2 of 32 individuals showed evidence of drug usage, the authors were cautious to say drug consumption was rampant, but they did provide direct and conclusive evidence of consumption of psychoactive substances. Furthermore, the Banisteriopsis vine is the only South American species studied that contains harmine. The vine is found only in Amazon basin, far away from the Azapa valley indicating the possibility of a vast trade network of Tiwanaku. Ultimately, I commend the authors for successfully providing the first direct archaeological evidence for the consumption of hallucinogenic herbs.

Ogalde, J.P., Arriaza, B.T., Soto, E.C. Identification of psychoactive alkaloids in ancient Andean human hair by Gas Chromatography/Mass Spectrometry, Journal of Archaeological Science (2008), DOI: 10.1016/j.jas.2008.09.036.