Wasous

New research by an international team raises questions about the timing and nature of early interactions between indigenous people and Europeans in North America.

A human face effigy from ceramic vessel from the Mantle site [Credit: Archaeological Services Inc./Andrea Carnevale]

The European side of first contact with indigenous people and settlement in northeast North America is well known from European sources. Until now it's been assumed that the finds of dated European artifacts provide a timeline for the indigenous peoples and settlements of this period as well. New research suggests this may be a mistake in cases where there was not direct and intensive exchange.

Radiocarbon dating and tree-ring evidence shows that three major indigenous sites in Ontario, Canada, conventionally dated 1450-1550 are in fact 50-100 years more recent. This dates the sites to the worst period of the Little Ice Age, around 1600.

"This seems extraordinary: Given this was only 400 years ago, how can we have been wrong by as much as 25 percent?" said first author Sturt Manning, the Goldwin Smith Professor of Classical Archaeology, chair of the Department of Classics and director of the Cornell Tree-Ring Laboratory.

Manning is lead author of "Radiocarbon Re-dating of Contact-era Iroquoian History in Northeastern North America," published in Science Advances. Other Cornell authors include Cornell Tree-Ring Laboratory senior researcher Carol Griggs '77, Ph.D. '06, and doctoral student Samantha Sanft. The paper represents the first major findings of the "Dating Iroquoia" project, a National Science Foundation-funded effort led by Manning and co-director Jennifer Birch (University of Georgia).

Previously, dates in the early contact period were based on the absence – and then presence – of types of glass beads and other European trade goods in excavated sites, along with shifts in material culture, such as changes in ceramic designs. Dates were assigned according to "time transgression," the assumption that when European goods are found in one place with a confirmed date associated with them, that same date can be used for other places where those trade goods are found.

"But goods don't get distributed evenly within societies or across distances," said Manning. "This is a vast area with complex local societies and economies, so the concept that everybody gets the same thing necessarily all at once is a bit ludicrous in retrospect."

The team's chronological findings dramatically rewrite how history has been understood in the region. The period of first European contact, rather than following major changes in Iroquoian society, can now be seen to coincide with those changes. According to Birch, an expert on Iroquoian societies, "Our work has shown that, at least for some communities, contact-era transformations happened much later and much more rapidly than previously assumed."

"Of course, we've dated only one site sequence, and there are many more," Manning said. "What this paper really shows is we now need to reassess all those site sequences where there's not a clear historical link or association."

The researchers first examined the Warminster site in Canada, believed to be visited by French explorer Samuel de Champlain in 1615. Using radiocarbon isotope and dendrochronological (tree ring) dating, combined with a mathematical technique, determined the indigenous settlement at the location to date from between 1585 and 1624, which corresponded with Champlain's visit. Archaeological evidence and provided confirmation of the accuracy of their techniques.

The team then assessed a series of well-known, high profile settlements, Draper-Spang-Mantle. In the 16th century, Iroquoian societies lived in village communities for approximately 10 to 50 years; once the local resources were exhausted, the community relocated the village. Archaeological evidence indicates that these three villages were occupied in sequence by the same ancestral Huron-Wendat community. Mantle, the latest site in the sequence, was shown to date to between 1599 and 1614, partly contemporaneously with Warminster.

Author: Linda B. Glaser | Source: Cornell University [December 05, 2018]

Why do people go to war when the consequences of warfare are so dramatic? Scholars have suggested that the motivations for participating in war either lie in the individual rewards warriors receive (to the victor goes the spoils) or because group members coerce them to participate for fear of punishment. Understanding the factors that motivate warriors to join war parties sheds light on some of the most fundamental aspects of human nature: How our ability to cooperate is linked to our most destructive tendencies.

In a new study, a team of researchers examined the social composition of raiding parties and their relationship to marriage alliances in an Amazonian tribal society, the Waorani of Ecuador [Credit: Pete Oxford/australscope]

In a new study, a team of researchers examined the social composition of raiding parties and their relationship to marriage alliances in an Amazonian tribal society, the Waorani of Ecuador. The Waorani formerly practiced lethal raiding, or small-scale warfare, as part of their social fabric. The anthropologists spoke in detail with tribal members about their raiding histories in an attempt to understand what drives individuals to participate in acts of war. Theirs is one of only a handful of datasets in the world with detailed information about what warfare looks like in small-scale societies prior to the intervention of the state.

They found that Waorani are actively joining raids with people who could provide access to ideal marriage partners for themselves as well as their children. Additionally, subtle coercion from in-laws appears to be a factor in joining raids. The relationships built through raiding resulted in meaningful bonds between the men, which could shed light on the evolution of friendship.

"A big debate in anthropology is what warfare and raiding groups look like in small-scale societies. Arguments have always been about this nice band of brothers--literally brothers, uncles, fathers all fighting side-by-side with one another," said Shane Macfarlan, assistant professor of anthropology at the University of Utah and lead author of the study. "But sometimes, kin are not enough. Warfare is about alliance building, relationships with other people where there might be something else to gain by fighting with one another--like marriage partners."

The Waorani

The Waorani are indigenous Ecuadorians from the lowlands of the Amazon Rainforest made up of 2,000 individuals today. When people of Euro-American descent first made contact with members of the tribe in 1958, the population consisted of 500 individuals residing in four mutually hostile territories. Within the territories, Waorani lived in neighborhoods of longhouses, called nanicabo. Each neighborhood was separated by a one- to two-days walk, and each nanicabo was separated by a 30- to 60-minute walk.

The Waorani formerly practiced lethal raiding, or small-scale warfare, as part of their social fabric [Credit: Kleverenrique/WikiCommons]

For the Waorani, the ideal marriage partners are bilateral cross cousins--for example a man's mother's brother's daughter or his father's sister's daughter. One of the ways to make alliances is through raiding. Lethal raiding was quite common amongst the Waorani; when an individual decided to raid, he would convince followers to join him.

"The benefit of making an alliance outside of your direct kin is that it expands your social universe for getting the things that you need, and one of the things that people need in all societies is mating partners," said Macfarlan.

Between 2000 and 2001, co-authors Jim Yost, Pam Erickson of University of Connecticut and Steve Beckerman of Pennsylvania State University interviewed almost all of the Waorani population aged 49 years or older--65 women and 55 men. The researchers collected detailed genealogical information from multiple generations, and cross-referenced the data with existing Waorani genealogies. They also collected raid histories that included the men who participated, the organizer, the victims, and the rationale for the attack. The researchers used marriages and births to establish a timeline of the raids. From 1917 to 1970, there were 550 raid reports. The researchers consolidated them into 49 separate raids that involved 81 people.

In-laws, brothers and marriage

Macfarlan and senior author Stephen Beckerman analyzed the make-up of the raiding groups and the raiders' marriage histories. If the "bands of brothers" model holds, then the raiders should include mostly direct ancestors or descendants of each other, known as lineal kin. If the groups were strategic alliances, then the individuals should consist of men who can provide marriage opportunities for each other--genetically related, but outside of lineal kinship. Because the researchers needed to be able to distinguish cousins, they only used individuals for whom they had grandparents' information. They analyzed the social composition of the 49 raids, including the 1041 individual relationships that emerged from the 81 men who participated.

Co-author Jim Yost (right) with a Waorani man discussing Waorani  territory during the data collection component of the project [Credit: Jim Yost]

Although males had a plenty of lineal kin to choose from for forming raiding parties, they selectively raided with non-lineal kin. They also found that men raided more frequently with men who were generically related to them, but from different lineages--the ideal marriage exchange partners. Indeed, the raiding alliances resulted in marriages for both the raiders, and for the raiders' children.

Yet another motivation to join raiding parties seemed to include some coercion. Macfarlan found that sometimes men got married first, then raided more frequently with his in-laws.

While scholars have typically assumed that warfare was either about individual rewards or coercion we find that this is a two-way street. "Sometimes people go to war to find alliance partners that gives them access to marriage opportunities, but other times guys get married first and then these marriage ties are leveraged to coerce people into warfare."

Evolution of friendship

Humans for the most part have three kinds of relationships: kinship, marriage and friendship. Traditionally, anthropologists only considered kinship and marriage as important. Recent interest has looked into the evolution of friendship itself. A common feature of friendship across cultures is that it promotes cooperation between people who are neither are kin nor our lovers, with our friends providing us with benefits that kin and lovers cannot. One context where friendship is extremely important is helping us deal with conflict from other people and groups, known as the Alliance Hypothesis.

The study's findings provide evidence for this hypothesis, Macfarlan said.

"The act of killing another human is a really traumatic act, which causes people to share something in common psychologically that establishes trust and fosters things like friendships," said Macfarlan.

The study was published in the journal Proceedings of the Royal Society B.

Source: University of Utah [December 03, 2018]

Shell middens are archaeological features consisting mainly of the remains of marine animals thrown away near settlements over hundreds or thousands of years. They are the debris of human activity. In Brazil, they are known by the Tupi word sambaqui.

Dental caries on the teeth of buried skeletons (oral pathology of individual MO59 (female, YA). (a) Left maxilla: A, dental wear; B, ante-mortem tooth loss; C, occlusal-dentin caries and pit caries; D, occlusal-pulp caries. (b) Mandible, occlusal view. (c) Mandible, lingual view on right side: E, M2: occlusal caries and related abscess and cervical caries; F, M3:  gross-gross caries and related abscess. (d) Mandible, buccal view on left side: G, M1: occlusal pulp caries, abscess, and alveolar resorption [Credit: Luis Nicanor Pezo-Lanfranco]

The sambaquis were left by people who lived between 8,000 and 1,000 years ago in coastal Atlantic Forest areas, traditionally considered peripheral to South America's first food production centers in the Andes and the Amazon.

A new study, however, presents strong evidence that sambaqui societies were not ordinary hunter-gatherers. Analysis of their middens shows that they cultivated or at least managed edible plants and had a rich diet with a substantial proportion of carbohydrates. Fapesp - São Paulo Research Foundation- FAPESP has supported the study.

Findings from the study have recently been published in Royal Society Open Science. It was conducted by researchers from Brazil and the United Kingdom using data collected at the Morro do Ouro and Rio Comprido sambaquis in Babitonga Bay near Joinville, Santa Catarina State.

"The significant levels of consumption of high-carbohydrate foods evidenced by these two sambaquis suggests the communities had a mixed subsistence economy that combined fishing and the collection of seafood with some form of plant cultivation," said Luis Nicanor Pezo-Lanfranco, a bioarchaeologist at the University of São Paulo's Bioscience Institute (IB-USP), first author of the article and a FAPESP grantee.

Pezo-Lanfranco conducted the study at IB-USP's Biological Anthropology Laboratory, led by Professor Sabine Eggers, in partnership with archeologists at the University of York (UK) and Joinville's Sambaqui Museum.

According to the traditional archeological view of prehistory in South America, the hunter-gatherers who left the shell middens maintained themselves mainly by foraging marine resources. This idea began to be contested in the 1980s when evidence was found that the sambaqui societies had a far more diversified economy.

The high frequency of sambaquis on the southern coast of what is now Brazil and the large volume of some of these shell middens, which also contain hundreds of human burials, are considered evidence of high population density, monumental architecture, and social complexity during the Middle to Late Holocene.

Dental caries on the teeth of buried skeletons, interpreted as evidence of a high-carbohydrate diet, are among the reasons for concluding that these communities had a more diversified economy and diet than previously believed.

Moreover, archaeological digs have identified remains of plants that may evidence incipient cultivation of food crops, including tubers (yam and sweet potato), corn, palm trees, soursops and sweetsops (Annonaceae).

The new study was based on oral pathology and stable isotope analyses performed directly on the skeletons. The analyses revealed unexpectedly high consumption of plant resources, i.e., carbohydrates, by the Morro do Ouro sambaqui people on the northern coast of Santa Catarina in the Middle Holocene (8,000-4,000 years ago).

The northern coast of Santa Catarina has the largest number of sambaquis in Brazil. Hundreds of shell mounds are scattered around Babitonga Bay.

"We analyzed the oral health and stable isotopes of human remains buried in the Morro do Ouro and Rio Comprido sambaquis to investigate the dietary habits of these communities during the Middle and Late Holocene," Pezo-Lanfranco said.

Finds made at Morro do Ouro have contributed significantly to the discussion of population density, health and disease, and cultural and dietary variability in Atlantic Forest coastal communities during the Middle Holocene.

Archaeological digs conducted there in the 1980s brought to light large amounts of remains of terrestrial and marine animals, artifacts, domestic structures, and human burials.

The animal remains were from several species of mollusk (clams, mussels, oysters), fish (mullet, croaker, seabass, pufferfish, catfish) and terrestrial mammals (lowland paca, white-lipped peccary). Polished stone tools and charred coconut remains have also been found.

According to Pezo-Lanfranco, 116 burials were excavated by several archaeological expeditions between 1960 and 1984. Carbon dating of bone collagen for this study showed that the site was occupied between 4,800 and 4,100 years ago. An analysis of minute dental calculus traces from the site performed in 2010 by Verônica Wesolowski, a researcher at the University of São Paulo's Museum of Archaeology and Ethnology (MAE-USP), had already identified grains of starch compatible with sweet potato, yam, and coconut.

At nearby Rio Comprido, archaeologists found polished stone knives and axes as well as 67 burials in the 1970s. The site was occupied in two phases: Rio Comprido 1 (RC1) between 5,600 and 4,300 years ago (Middle Holocene) and Rio Comprido 2 (RC2) between 4,000 and 3,400 years ago (Late Holocene).

Morphological analysis performed for the study included the determination of sex and age as well as oral pathologies in 70 individuals, 42 from Morro do Ouro (MO) and 28 from Rio Comprido (16 RC1 and 12 RC2). Stable carbon and nitrogen isotopes from 36 individuals were analyzed, 20 from MO and 16 from RC (nine RC1 and seven RC2).

Using 11 oral health markers, a total of 1,826 alveoli and 1,345 teeth from these 70 individuals were examined. Most of the skeletons analyzed were found to be male and aged 20-49 on average at the time of death.

"The frequency of dental caries ranged from 7.6% to 13.2% of the samples. This was more than expected for groups of hunter-gatherer-fishers and more compatible with the pattern found for the first farmers of the Late Holocene in other regions, such as the Andes," Pezo-Lanfranco said.

Analysis of teeth from Late Holocene hunter-gatherers found in Patagonia, for example, showed caries frequencies ranging from 3.3% to 5.19%, while samples from more recent sedentary populations in Patagonia displayed a frequency of 10.17%.

Caries types varied considerably across the two sambaqui sites, but statistically significant differences were observed only in cervical (extraocclusal) lesions.

The frequency of occlusal caries was generally high in all groups, ranging from 53.7% (MO) to 70% (RCI) of the individuals analyzed. The highest frequency of enamel caries was recorded for RC1, whereas MO had the highest frequency of extraocclusal caries.

Carious lesions have been associated with diets rich in fermentable carbohydrates and sugar. The frequency of extraocclusal caries and cavities on smooth tooth surfaces increases when diets are rich in cariogenic foods.

"It's probable, therefore, that the Morro do Ouro people had a more cariogenic and refined diet than the Rio Comprido 2 people, quite possibly because they cooked their food, for example," Pezo-Lanfranco said.

Processed carbohydrates

Dietary estimates based on stable isotopes from teeth and bone showed that the main protein source was fish, ranging from a low of 33% in people from MO to 87%-90% in RC2.

Plants accounted for the largest share of calorie intake in MO (48%), followed by fish (44%) and hunted terrestrial mammals (8%).

Bone collagen data from RC1 showed fish to be the main source of calories (48%), followed by plants (44%) and terrestrial mammals (7%).

Pezo-Lanfranco found similar proportions for RC2: fish (48%), plants (42%) and terrestrial mammals (10%). All percentages are averages, with individual values varying considerably.

The main protein source was fish for individuals from MO (58%-84%), RC1 (66%-85%) and RC2 (74%-83%). These levels are slightly higher than the values found for prehistoric and contemporary hunter-gatherers.

"The high proportion of chronic or static caries among individuals from RC1 suggests a less cariogenic diet than among individuals from RC2 and MO. This may be associated with the phosphate and calcium present in diets of marine origin, as you would expect for fisher communities," Pezo-Lanfranco said.

"On the other hand, the higher frequency of deep and extraocclusal caries in RC2, and particularly in MO, points to widespread consumption of cariogenic and processed carbohydrate from roasted or boiled plants. The evidence from RC and MO suggests the existence of some kind of plant cultivation, albeit incipient."

Cervical caries, the most frequent type of extraocclusal caries in individuals from MO (29%), are associated with the frequent consumption of sucrose and solid fermentable starch, high levels of salivary lactobacilli, and the deposition of cervical calculus with gingival recession (receding gums).

"Cervical caries frequencies of around 16% have been reported for Pleistocene hunter-gatherers in northern Africa and interpreted as the first signs of the systematic harvesting and storing of high-carbohydrate wild plant food," Pezo-Lanfranco said.

In Andean agriculturalists, cervical caries are attributed to the consumption of fermented beverages made from cassava, corn, and other starchy foods. Previous studies have shown that sucrose, starch with sucrose, fructose and dextrose in descending order stimulate the production of smooth-surface and cervical caries, while high amounts of maltose and starch tend to lead more to cervical caries.

"So the MO diet was probably richer in cariogenic carbohydrate than the RC diet, and comparable to the diets of some agricultural peoples in antiquity," Pezo-Lanfranco said.

The dental wear index in MO and RC was lower than for several sambaqui communities studied elsewhere. The RC2 diet seems to have been more abrasive than the MO diet. Stone vessels and grindstones found at MO may have been used to make flour. Microscope analysis of these implements is pending.

"This study puts the Neotropics on the map of the world's food production centers in antiquity. The Atlantic Forest coast has mostly been peripheral to this narrative despite its unique biodiversity and the archeological records of dense human occupation since the Middle Holocene. The new study challenges this traditional view," Pezo-Lanfranco said. "We assembled strongly convincing evidence for high-carbohydrate dietary habits among hunter-gatherers in the Joinville region some 4,500 years ago. Confirmation that they had cultivar production systems and how far they had progressed with domestication of the plant species concerned awaits further research."

Source: Fundação de Amparo à Pesquisa do Estado de São Paulo [December 03, 2018]

Argentine and Spanish researchers have used statistical techniques of automatic learning to analyze mobility patterns and technology of the hunter-gatherer groups that inhabited the Southern Cone of America, from the time they arrived about 12,000 years ago until the end of the 19th century. Big data from archaeological sites located in the extreme south of Patagonia have been used for this study.

Atlantic Coast of Isla Grande de Tierra del Fuego, Punta Torcida sector [Credit: Ivan Briz i Godino]

The presence of humans on the American continent dates back to at least 14,500 years ago, according to datings made at archaeological sites such as Monte Verde, in Chile's Los Lagos Region. But the first settlers continued moving towards the southernmost confines of America.

Now, researchers from Argentina's National Council for Scientific and Technical Research (CONICET) and two Spanish institutions (the Spanish National Research Council and the University of Burgos) have analyzed the relationships between mobility and technology developed by those societies that originated in the far south of Patagonia.

Selk'nam people, an example of a more pedestrian group, without nautical technology, although the marine resources were intensely exploited by those who lived near the coast [Credit: C. W. Furlong (January 1908)/ End of the World Museum (Ushuaia, Argentina)]

The study, published in the Royal Society Open Science journal, is based on an extensive database of all available archaeological evidence of human presence in this region, from the time the first groups arrived in the early Holocene (12,000 years ago) until the end of the 19th century.

This was followed by the application of machine learning techniques, a statistical system that allows the computer to learn from many data (in this case, big data from characteristic technological elements of the sites) in order to carry out classifications and predictions.

Example of a group with nautical technology: Yámana people in the Anglican mission of Bahía Tekenika (Tierra del Fuego),  portrayed in the late 19th or early 20th century. Darwin lived with them during the second voyage of the Beagle [Credit: Ivan Briz i Godino/Archives of the South American Missionary Society (United Kingdom)]

"It is by means of automatic classification algorithms that we have identified two technological packages or 'landscapes': one that characterizes pedestrian hunter-gatherer groups (with their own stone and bone tools) and the other characterizing those that had nautical technology, such as canoes, harpoons and mollusc shells used to make beads," explains Ivan Briz i Godino, an archaeologist of the National Council for Scientific and Technical Research (CONICET) of Argentina and co-author of the work.

"In future excavations, when sets of technological elements such as those we have detected appear, we'll be able to directly deduce the type of mobility of the group or the connections with other communities," adds Briz.

Technological landscapes of nautical mobility (red circles, with some blues that are less well classified by the algorithm) and pedestrian mobility (orange and purple circles) in hunter-gatherer groups that lived  in the extreme south of South America [Credit: Briz et al. 2018]

The results of the study have also made it possible to obtain maps with the settlements of the two communities, and this, in turn, has made it possible to locate large regions in which they interacted and shared their technological knowledge. In the case of groups with nautical technology, it has been confirmed that they arrived at around the beginning of the Mid-Holocene (some 6,000 years ago) from the channels and islands of the South Pacific, moving along the coast of what is now Chile.

"Traditional archaeology identifies sites, societies and their possible contacts on the basis of specific elements selected by specialists (such as designs of weapon tips or decorative elements), but here we show that it is more interesting to analyse sets of technological elements as a whole, using artificial intelligence techniques that allow us to work with large data volumes and without subjective prejudices," concludes Briz.

Source: FECYT - Spanish Foundation for Science and Technology [December 03, 2018]

Archaeologists of the Far Eastern Federal University (FEFU) found three burials of the ancient inhabitants of South America aged from 6 to 10 thousand years. The excavations were carried out in Atahualpa Canton, Ecuador. The findings belong to the Las Vegas archaeological culture of the Stone Age.

The ancient skull excavated in Loma Atahualpa, Ecuador, 2018, by archaeologists of the Far Eastern Federal University [Credit: FEFU]

Analysis of artifacts will help scientists understand the development of ancient cultures on the shores of the Pacific Ocean and clarify the origin and development of ancient American civilizations. Research is being jointly conducted by FEFU and Primorsky Polytechnic University in Guayaquil (ESPOL, Ecuador).

Previously, FEFU scientists investigated the famous Neolithic settlement in Real Alto. In 2018 they decided to study an earlier site in order to trace the development of ancient cultures on the Pacific Coast opposite to the Pacific Coast of Russia (Russian Far East).

"The archaeological site of Loma Atahualpa is more archaic than Real Alto, its materials are transitional from the Mesolithic to the Neolithic. We excavated three burials that were probably made at different times. This will make it possible to compare their materials and retrieve the new information on the development of ancient cultures in the period from 10 to 6 thousand years ago," said the head of the expedition Alexander Popov, director of the Educational and Scientific Museum of The School of Humanities of FEFU.

Expedition materials are processed by experts from several countries. The stone tools found were examined at Tohoku University (Japan) for traces of mechanical activity in order to understand how they were used. There were also sent samples for radiocarbon dating. Simultaneously, anthropologists from The Kunstkamera (Peter the Great Museum of Anthropology and Ethnography, St. Petersburg) and the Institute of the Problems of Northern development, Siberian Branch of the Russian Academy of Sciences (Tyumen, Russia) began to study the morphological features of the human remains found.

"In the course of working with Ecuadorian colleagues, we have learned that our research attracted the obvious attention of scientists. Last year's symposium, which was organized at the Real Alto Museum, was attended by colleagues from the United States, Canada, Brazil, Japan, Poland and other countries. We also cooperate with partners from several European countries and the Russian Academy of Sciences," added Alexander Popov.

Source: Far Eastern Rederal University [November 26, 2018]

The ancient Maya are not particularly known for their love of freshwater mussels. Mathematics, maize, pyramids and human sacrifice, yes. But bivalves? Not so much.

The Maya cut freshwater mussels into small rings that showed off their iridescent mother-of-pearl interiors and sewed these sequin-like "sparklers" into clothing [Credit: Florida Museum/Kristen Grace]

Yet Florida Museum of Natural History archaeologists Ashley Sharpe and Kitty Emery could not sift through a single bag of material from their dig sites near the Mexican-Guatemalan border without turning up mussels: discarded shells from meals, shells used as paint pots, shell pendants, shell discs sewn into clothing like iridescent sequins and ground shell powder that may have been an early form of glitter. They even found corpses carefully buried with bivalves clasped in their hands.

But when Sharpe and Emery documented their findings, they ran into a problem - matching the right name to the right mussel species.

"Either no one had given names to them or we had the problem where naturalists had given 50 different names to one thing," said Sharpe, a University of Florida doctoral graduate and now a research archaeologist at the Smithsonian Tropical Research Institute. "We could tell the Maya were identifying different types of mussels and using them in different ways, but I would end up just referring to them as 'mussel a' and 'mussel b.'"

Enter John Pfeiffer, a Florida Museum doctoral student researching freshwater mussel classification and evolution. After listening to a research presentation by Pfeiffer, Sharpe and Emery, curator of environmental zooarchaeology, struck a deal with him - they would bring fresh specimens from the field if he would complete the DNA analysis to identify them.

Archaeologist Kitty Emery said Mayan artwork depicts people wearing carved bits of mussels as jewelry or woven into clothing [Credit: Florida Museum/Kristen Grace]

Their collaboration produced the first molecular study of freshwater mussels native to Mexico and Central America, adding what Pfeiffer described as a crucial and long-missing piece to our understanding of North American freshwater mussels.

"This is the most geographically inclusive interpretation of North American freshwater mussel evolution," said Pfeiffer, the study's lead author. "You really can't talk comprehensively about North American freshwater mussels unless you consider these groups in Mexico and Central America, but if they existed south of Texas, they pretty much got ignored."

North America is the epicenter of freshwater mussel diversity and home to the most species-rich mussel subfamily, Ambleminae, whose classification got a shake-up as a result of the team's study. Amblemines have garnered the bulk of North American mussel research, partly because of the striking way they disperse their young.

Several amblemine groups attract host fish by using convincing "lures" that resemble easy meals such as small fish, insects and crayfish. When a fish nibbles the lure, the female squirts out tiny parasitic larvae, which clamp down on the fish's gills or fins where they will remain until they are large enough to drop off and bury in the riverbed. Without this strategy, the mussel's offspring would be flushed helplessly downstream.

This mussel pendant, about the width of a baseball, was found at a Mayan burial site in Guatemala [Credit: Florida Museum/Kristen Grace]

Pfeiffer got hooked by these lures as well.

"I was amazed that animals that look like rocks full of snot have these remarkable traits and behaviors that can fool really visually oriented predators," he said. "How they evolved such accurate replicas of their hosts' prey made me want to study natural selection and evolution."

Mussels play a key role in the health of freshwater systems, acting as the livers of rivers and streams by filtering and cleaning their waters. But mussel numbers are plummeting globally. Damming, water pollution, invasive species, the loss of their host fish and habitat degradation have put freshwater mussels among North America's most endangered animals, Pfeiffer said.

"Over two dozen species have gone extinct in the last 200 years," he said.

Making sound conservation decisions hinges on a detailed knowledge of which species live where, but the lack of molecular data on Mexico and Central America's mussel species left what Pfeiffer called a "black hole" in our comprehension of North America's mussels.

The abundance of names assigned to Mexican and Central American mussels may have led to an overestimation of the region’s mussel diversity, Pfeiffer said. DNA showed that many mussels with unique names belong to the  same species [Credit: Florida Museum/Kristen Grace]

"It was like Mexican and Central American mussels hardly existed, as if they were not critically important to understanding the evolution and ecology of the group," Pfeiffer said. "That sentiment is reflected in many treatments of North American freshwater mussels. But these regions share many of the same lineages. Mussels don't care about borders."

In a previous study, Pfeiffer, Sharpe, Emery and Larry Page, Florida Museum curator of ichthyology, used DNA evidence to show that a Central American mussel species listed as federally endangered was nearly genetically identical to a common species in the U.S. The populations in Mexico and Guatemala just represented the species' southernmost residents.

"It seemed odd to us that this species that is widespread from Minnesota to southern Texas suddenly became a distinct and critically endangered species once you crossed the Rio Grande," Pfeiffer said. "The specimens Ashley collected from Guatemala allowed us to test our hypothesis and ultimately correct the species' classification. This is one example of how the mussel diversity of Mexico and Central America may have been overestimated."

But he understands firsthand how classifying species without the help of DNA can be difficult. When Sharpe and Emery returned with their specimens and tissue samples, he sorted the shells based on what he suspected the species groupings were. Circular, bumpy shells went in one pile, flat shells with white interiors in another, and so on. Then the DNA results rolled in.

"We got the molecular data back, and it pretty much trashed many of our shell-based hypotheses," Pfeiffer said. "Some shells looked like dead ringers for belonging to one particular group but ended up being distant relatives. Shells that I had sorted into six piles based on their characteristics had nearly identical molecular sequences. There's clearly a lot of plasticity in shell shape."

Mussels’ rich colors fade over time. Seeing fresh examples of the archaeological specimens helped Sharpe and Emery understand why the Maya favored certain species for ornamentation [Credit: Florida Museum/Kristen Grace]

The DNA clarified species' identities and their relationships to one another, providing a baseline for future conservation assessments, Pfeiffer said. The team also recognized a new tribe of amblemines that could help scientists better understand the evolution of the subfamily's sophisticated host infection strategies.

But the researchers have plenty of work ahead.

"We've made some good progress, but there are still many more taxa to be sampled and regions to be explored," he said. "Really, we've just scratched the surface."

Meanwhile, in Guatemala, Sharpe is turning her attention to patterns she and Emery had noticed previously, with species names in hand - how some mussels were once common and then completely disappeared or how the Maya switched from eating some species to using them exclusively for ornamentation. Having modern specimens to compare with archaeological ones also clarifies why the Maya may have used certain species for specific functions. Many of the now-bleached shells used for jewelry or burial décor had lustrous, violet interiors when they were plucked fresh from the river.

"There were certain species used in burials regionwide, but only at one point in time - it was like a fad," Sharpe said. "Working with John allowed us to look at things in a way that we never thought we could do. Without the genetic data, we really couldn't classify these shells."

As a mussel geek, how does Pfeiffer feel about the lifestyles of the ancient Maya, whose diet, clothing, architecture and burials were so populated with mussels?

"I'm kind of jealous," he said.

The team published its findings in Zoologica Scripta.

Author: Natalie van Hoose | Source: Florida Museum of Natural History [November 26, 2018]