Amazonian study quantifies key role of grandparents in family nutrition

A Tsimane grandmother (right) provides support for her infant daughter, her adult daughter (left), granddaughter and grandson.

By Carol Clark

Anyone who has ever loved a grandmother or grandfather knows the nurturing role that grandparents can play. A study of indigenous people in Amazonia, who survive on food they hunt, forage or cultivate, quantifies the evolutionary benefit of that role. The results show that grandparents contribute a biologically significant amount of food calories to their extended families.

Proceedings of the Royal Society B published the results of the study of the Tsimane people of Bolivia, led by Paul Hooper, an anthropologist at Emory University.

“We quantified the net flow of calories among individuals in an environment where access to food is limited and depends on people generating it themselves,” Hooper says. “The results support the theory that grandparents are key to our relatively long childhood and long lifespan, which are a big part of what makes us human. Their efforts have likely been underwriting human society for hundreds of thousands of years.”

The study found that fathers and mothers contributed the most net calories to their nuclear family unit, followed by grandfathers and grandmothers, then uncles, aunts and children above the age of 12.

Relative to other primates and mammals, humans mature later and live longer, including many post-reproductive years. Evolutionary theories have proposed that intergenerational resource transfers bolster these distinctive features of human life history. This new study is the first to fully unite the production of resources over a lifetime with inclusive fitness theory, and then test the unified model in an empirical analysis.

Members of a family work together to prepare a meal from ingredients they have gathered from their environment. "About 95 percent of their food comes directly from their own labor," Hooper says.

“Our data give a clear picture of how the life history of our species is supported by high surplus food production in older age and the redistribution of that surplus to younger kin,” Hooper says. “Beyond showing that food resources flowed from older to younger generations, we were able to predict how much each person gave to each other, based on their relative productivity and the closeness of their relationship.”

Hooper led the research as a graduate student at the University of New Mexico and then as a post-doctoral fellow at the Santa Fe Institute. His co-authors include anthropologists Hillard Kaplan, Michael Gurven and Jeffrey Winking.

The researchers spent five years collecting data on 239 Tsimane families from eight villages. The Tsimane (pronounced Chee-mahn-AY in Spanish) live in small, isolated communities along the Maniqui River in the Amazonian rainforest that are only accessible by canoe or logging roads. These communities speak their own language, lack modern sanitation and electricity, and have access to few consumer goods beyond axes, machetes and other basic supplies.

The Tsimane clear small patches of forest to cultivate cassava, plantains, rice and corn. They also forage plants and fish and hunt meat in the form of peccary, deer, tapirs, monkeys and capybara (a large rodent). “About 95 percent of their food comes directly from their own labor,” Hooper says. “It’s an isolated, small-scale society that gives us an idea of the way humans lived before modern industrialization.”

The study broke down average caloric intake by various age groups of the participants, ranging from about 700 calories per day for an infant to more than 3,000 calories per day for adults. They also quantified the amount of calories each family member contributed to the household, from a bushel of plantains or a kilo of rice to the meat of a butchered deer.

The evolutionary value of grandfathers has been largely overlooked, Hooper says.

The results showed that Tsimane parents and grandparents provide net economic contributions to kin into the seventh decade of life. Households with higher food productivity and fewer dependents provided net transfers to closely related, usually younger, households with lower productivity and more dependents.

The value of grandmothers had been highlighted in previous studies linking them to improved outcomes for grandchildren. The contribution of grandfathers, however, has been largely overlooked, Hooper says.

While food is a limiting resource among the Tsimane, Hooper notes that in order to conduct a similar study in an industrialized society the focus should shift from food to money and time.

“Whether you’re a hunter-gatherer or an accountant, you’re good at what you do because someone supported you while you developed and learned skills,” Hooper says. “The economics of learning are what makes grandparents so important to humans compared to other primates.”

In modern, fast-paced societies, undergoing rapid technological change, the value of grandparents may be overlooked, he adds. “When technology moves at a fast rate, it can shift the age of competence to younger ages. We’re in danger of not recognizing the wisdom of older people, accumulated over lifetimes.”

Hooper, who lost his last grandparent, his maternal grandmother, a few weeks before the study was published, says she influenced his career choice. “She completed a graduate degree in biology during the 1930s, so she was way ahead of her time,” he says. “I learned about Darwin and evolution from her. She taught me the importance of biology for understanding ourselves and our place in the universe.”

Photos courtesy of Paul Hooper

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How 'Fifty Shades' is coloring views of fantasy

Anastasia Steele (Dakota Johnson) and Christian Gray (Jamie Dornan) in the movie version of "Fifty Shades of Grey," which is only rated R but reportedly shows at least 20 full minutes of sex.

Emma Green writes in The Atlantic about the social implications of the blockbuster fantasy novel and movie "Fifty Shades of Grey." Below is an excerpt from the article:

"In some ways, it’s remarkable that a phenomenon like 'Fifty Shades' has even been possible. 'Oral sex, anal sex—those are all things that were at one time illegal,' said Paul Wolpe, the director of the Center for Ethics at Emory University. Sodomy, for example, was considered a felony in every state until 1962, and until the Supreme Court ruled against sodomy bans in its 2003 decision in Lawrence v. Texas, it was still illegal in 14 states.

"Today, 'there are lots of differences in the moral composition,' he said. 'There’s no unified moral view, so … the argument then becomes: My morality is different than yours—what right do you have to oppose me?'

Read the whole article in The Atlantic.

The other butterfly effect

Humans have come up with many ways to protect ourselves from infectious diseases.

“We used to think we were alone with this, but now we know we’re not. Now we know there’s a lot of animals out there that can do it, too,” says Emory biologist Jaap de Roode in a TED talk. (TED is currently featuring de Roode's talk from last November on its national Web site.)

In recent decades, scientists have learned that chimpanzees can use plants to treat their intestinal parasites, as can elephants, sheep, goats and porcupines. “And even more interesting than that is the fact that recent discoveries are telling us that insects and other little animals with smaller brains can use medication, too,” says de Roode.

For the past 10 years, de Roode has studied monarch butterflies and how they get sick from parasites. He discovered that female monarch butterflies are able to use medicinal milkweed plants to reduce the harmful effects of the parasites on the butterflies' offspring.

“This is an important discovery, I think, not just because it tells us something cool about nature, but also because it may tell us something more about how we should find drugs,” de Roode says. “Most of our drugs derive from natural products, often from plants. In indigenous cultures, traditional healers often look at animals to find new drugs. In this way, elephants have told people how to treat stomach upset and porcupines have told people how to treat bloody diarrhea. Maybe one day we will be treating people with drugs that were first discovered by butterflies. And I think that is an amazing opportunity worth pursuing.”

De Roode is one of the featured speakers for the 2015 Darwin Day Dinner in Atlanta on Sunday, February 15. The title of his talk is "How Darwin laid the groundwork for understanding infectious disease." Tickets for the event, sponsored by Atlanta Science Tavern, sold out within days after they came available a few weeks ago.

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In the Balkans, resilience is rooted in knowledge of wild plants

The unripe fruit of Prunus domestica, in the rose family, is a favorite snack for Gorani children.

By Carol Clark

Traditional communities living in isolated, rural areas with little money or infrastructure tend to have one thing in common: Resilience rooted in intricate knowledge of their natural environment, especially plants.

This knowledge may be relevant to some of the biggest problems in plant science, including climate change, conservation biology, food security and human health, says Cassandra Quave, an ethnobotanist at Emory University.

Quave led an ethnobotanical study centered on a remote corner of the Balkans that was published in the journal Nature Plants. Her co-author is Andrea Pieroni from the University of Gastronomic Sciences in Pollenzo, Italy.

“Ethnobotany is the study of the interactions of people and plants,” Quave says, “but it has also been described as ‘the science of survival.’ People’s knowledge of which plants are beneficial, and how to harvest and preserve those plants, can make a huge difference in the overall well-being of a community.”

An Albanian describes plant uses.

Emory’s Center for the Study of Human Health funded the study, with additional support from the University of Gastronomic Sciences.

The study compared how two different cultures used plants in the Gora region of northwestern Albania, near the border with Kosovo. The researchers focused on a rural district of Gora that is one of the most economically disadvantaged in Albania. The two cultures in the study, Albanians and the Gorani ethnic minority, were both Muslim and subsisted primarily on small-scale agricultural, especially potato farming. The area is mountainous and many “roads” are unpaved, rocky paths. Some communities can be cut off completely from the outside world by heavy snows during the long winters.

“This area was heavily affected by the Balkan conflict of the 1990s,” Quave says. “The adults there have living memories of extremely challenging times. Even in peace time, life is difficult.”

The researchers conducted interviews with more than 100 residents about 104 different species of plants in their local environment. They recorded 418 uses of these plants for a broad spectrum of food, health, ritual and economic purposes.

The plant uses of the two cultures tended to overlap when it came to food, the study showed. Stinging nettle, for example, is a dietary staple among both the Albanians in the study and the Gorvani. “They boil nettle and use it the way we would spinach,” Quave says, sometimes mixing it with cheese, and baking it into local pastries known as byrek or pita.

A willow tree next to a Gorani home.

The researchers also found 77 divergent uses for plants between the two cultures, including 43 plant species. “Culture affects the way people view the natural environment,” Quave says. “And those views can affect everything from home healthcare practices to diet and local economies and conservation issues.”

The Albanians in the study, for example, reported less of an affiliation with a species of willow tree known as Salix alba, while the Gorani often choose to plant this tree around their homes and have many uses for it. “It’s what we call a cultural keystone species because it is so entwined with their way of life,” Quave says.

When a Gorani man wants to propose marriage to a woman, he may dig up a willow sapling and place it by her front door. If the woman accepts the proposal, the family plants the sapling in their field. If she rejects the suitor, the sapling becomes firewood.

Both the Gorani and Albanians use willow branches with leaves as protective amulets over their doors. And they add willow leaves to the fodder of their livestock once a year, along with some other plants, because they believe it helps keep the animals safe and healthy, Quave says.

Another example of a tradition used primarily by the Gorani involves the use of the plant Nepeta cataria, commonly known as catnip, to treat fright. “If a child has a nightmare,” Quave says, “they might brew a cup of catnip tea to soothe them.”

To store up supplies for winter months, both the Albanians and Gorani in the study use lactic fermentation to preserve food. If they need starter culture for fermentation, they use the roots from certain plants.

“They have a great deal of knowledge about their local environment that has been handed down to them through generations,” Quave says. It’s important to record that knowledge, she says, both because it could have possible relevance for science and because it could help communities improve their well-being.

“A lot of international attention has been focused on the Balkans to try to support reconciliation and development,” she says. “If you really want to help local communities in a way that’s sustainable and culturally sensitive, it’s important to have a detailed understanding of how they interact with their environment.”

Photos courtesy of Cassandra Quave

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Tapping nature to clean wastewater

In the WaterHub's 2,200-square-foot greenhouse, campus wasterwater is filtered and circulated among plant roots, where microbes naturally consume organic material.

By Kimber Williams, Emory Report

A new Emory facility, called the WaterHub, uses adaptive ecological technology to naturally break down organic matter in wastewater. The WaterHub is projected to help Emory reclaim some 300,000 gallons of campus wastewater daily, cutting potable water consumption as much as 35 percent and saving the university millions in water utility costs over a 20-year period, according to Matthew Early, vice president for Campus Services.

"Emory is a leader in sustainability," Early says. "With this facility, we’re taking a major step forward in becoming one of the first in the nation with this technology for cleaning our own wastewater."

Even as the facility was being constructed last semester, it was being put into service — Emory students used it for research by monitoring the changing microbiology of wastewater samples as the new project was ramping up.

Read more about the WaterHub.