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Enjoy Some Chocolate-- And Some Chocolate Science, Too

Happy Valentine's Day-- enjoy some chocolate

Tomorrow is Valentine's Day, which for many people means gifts, including gifts of chocolate.

Not that chocolate gift giving is recession proof. A 2009 article from Nielsen market research predicted that sales of chocolate for Valentine's Day would reach $345 million, enabling purchase of 58 million pounds of chocolate. But in 2010, the National Retail Federation found that couples were cutting back plans for Valentine's Day spending by 5%. And chocolate wasn't the first choice of men or women: more men planned to give flowers or cards than candy, while women were more likely to plan on giving cards. Still, this report predicted that 48 million pounds of chocolate would be sold in the week leading up to Valentine's Day.

Meanwhile, international trends suggest that chocolate is headed toward price ranges where it may be beyond most people's reach. A story from Canada's CTV recently quoted a British chocolate market authority saying that "consumption is increasing faster than cocoa production - and it's not sustainable." The New York Times recently covered the story of the rediscovery of a rare variety of Theobroma cacao (the technical name for the cacao plant) growing at an unexpected altitude in northern Peru. This variety produces a chocolate described as "intense, with a floral aroma and a persistent mellow richness", "extremely smooth when melted, with a full-bodied, nutty flavor that was not bitter". All the cacao beans from almost 200 cacao farmers in this small area is sent to Switzerland for processing, and sells for a reported $12 per two ounces. That's $96 a pound.

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Chocolate has traditionally been associated with this holiday about love because it makes people feel good.

And increasingly, we are told, chocolate does more than make you feel good; it can help keep you healthy. A German study of almost 20,000 people tracked for ten years found that eating the equivalent of one square of dark chocolate a day was associated with lower blood pressure and decreased risk of heart attack. This is only the latest in a line of studies showing similar benefits.

Cacao beans: start of a luxury treat
Research published in 2006 by an international team found that epicatechin- a flavonol in chocolate- improved circulation of the blood. Chocolate is believed to have antioxidant effects. Harvard Medical School published an overview of studies of these and other possible medical benefits of chocolate, including improving blood pressure and insulin sensitivity and aiding blood clotting.

Chocolate chemistry is complex. The highest health benefits of chocolate come from the least processed form, dark chocolate, which brings more chocolate compounds and less added sugar.

Among the suite of chemicals chocolate contains are traces of anandamide, a chemical that binds to the same receptors in the brain that respond to cannabinoids- the active chemicals in marijuana. Also present is tryptophan, which leads to the production of serotonin, a neurotransmitter that improves mood and encourages relaxation. Chocolate contains low concentrations of phenylethylamine, an amphetamine-like chemical linked to the release of dopamine. Another similar chemical in chocolate is tyramine. Finally, eating chocolate triggers the release of endorphins in the brain, leading to feelings of well-being. Most of these chemicals are found in very low concentration, but they are remarkably consistent in their biological effects with the good feelings chocolate lovers ascribe to their drug of choice.

My own research on chocolate origins has been most indebted to another chemical compound: theobromine. Named after the genus of the cacao plant, Theobroma cacao ("cacao, food of the gods"), theobromine is a methylxanthine, related to caffeine (which is also present in the cacao plant).

Theobromine is the key to identifying cacao residues in archaeological sites in the Americas where the cacao plant (or its relative, Theobroma bicolor) was in use. When found outside the natural range of related plants in northern South America, theobromine means cacao. This has made it possible for researchers in Central America to detect chocolate use, despite the fact that the plant is entirely destroyed in the process of preparation and consumption.

By using water, alcohol, and even chloroform to dissolve chemicals deposited in the porous walls of pottery suspected of having been used to hold chocolate drinks, and subjecting the extracts to chemical analysis, we can tell when an empty bowl, bottle, or drinking cup once contained chocolate.

When we published our results of analysis of our first set of sherds from Puerto Escondido in northern Honduras in 2007 in the Proceedings of the National Academy of Science, our 1150 BC date for one sample pushed the earliest known dates for cacao back by more than 500 years. Not long after, another research team reported positive results from even earlier samples from sites in Mexico. There is every reason to expect that new analyses of very early pottery excavated throughout Mexico and Central America will give us evidence of early chocolate in many different areas between 2000 and 1000 BC.

There are other chocolate discoveries still to be made. In early 2009, archaeologist Patricia Crown published her analysis of residues from tall cups found in Chaco Canyon, in New Mexico- far north of the area where the cacao plant grows, and far from the nearest known centers of cacao use. Now that we know chocolate had spread this far north in antiquity, we need to start checking possible chocolate pots from other areas in the Americas.

So happy Valentine's Day! As you share chocolate with your loved one, think about the untold stories of chocolate that archaeologists, medical researchers, and chemists are working to discover for you.

A special note: this is an annual Valentine's Day blog post, updated to reflect news from the year in chocolate research. The original appeared in 2010 on the Berkeley Blog.

 

Rosemary Joyce, Ph.D., is a professor of anthropology at UC Berkeley.

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