November 13, 2013
None of these drinks, though, has anything on the tradition of drinking spicy beverages in Mexico. A new analysis of ancient pottery unearthed from archaeological sites near Chiapa de Corzo, in southern Mexico, shows that people were using chili peppers to make their drinks spicy as far back as 400 BC.
The analysis, conducted by a group of researchers led by Terry Powis of Kennesaw State University, was published today in PLOS ONE. As part of the study, the scientists chemically tested 13 pottery vessels that had been excavated from a series of sites in the area linked to speakers of the Mixe-Zoquean group of languages—closely related to the language of the Olmec civilization—and were previously dated to years ranging from 400 BC to 300 AD.
When they scraped tiny samples out of the inside of each of the vessels, used chemical solvents extract organic compounds, and analyzed them with liquid chromatography testing, they found dihydrocapsaicin and other irritants that serve as evidence that Capsicum species, the taxonomic group that includes spicy chili peppers, once filled five of the vessels. Based on the vessels’ shape and prior archaeological work on the Mixe-Zoquean culture, the researchers believe they were used for all sorts of liquids—likely beverages, but perhaps condiments or sauces.
Previously, research by Smithsonian scientists had shown that chili peppers were domesticated much earlier—perhaps as far back as 6000 years ago—in Ecuador. This new research, however, is the oldest evidence of chili pepper use in
Central North America, and the first known instance of their use in ancient beverages, rather than in solid food.
Interestingly, the researchers originally began the project looking for evidence of the ancient use of cocoa beans in beverages. But their testing didn’t reveal any traces of cocoa left behind in the vessels, suggesting that the tradition of spicy drinks came first, and chocolate flavoring was only added to such drinks later on.
Other contextual evidence also suggests that the spicy drink of in Mixe-Zoquean culture differed significantly from the spiced hot chocolate enjoyed in Mexico today. Three of the vessels were found buried in the tombs of elite-status individuals, while the other two were excavated from temple-like structures. This context, they say, suggests that the beverages might have been used in ceremonial and ritual circumstances.
The authors note that this doesn’t rule out the possibility that the beverages were commonly drunk as well—a more thorough survey of vessels would need to be conducted to know for sure. Additionally, the researchers speculate that rather than a flavoring, chili peppers might have been ground up into a paste and coated on the walls of vessels as an insect and vermin repellent. If that was indeed the case,then bless the serendipity of whoever put liquidy chocolate into one of those vessels and created the wonder that is spicy hot cocoa.
November 12, 2013
In the summer of 2010, husband-and-wife paleobiologist team Z. Jack Tseng and Juan Liu traveled to the Zanda Basin in western Tibet with a group of colleagues. The remote area, a week’s drive from Beijing and near the border of Pakistan and China, is “basically badlands everywhere, with deeply cut valleys throughout,” Tseng says.
To explore the valleys, the team drove up dirt trail after dirt trail before coming upon a dense patch of fossils sticking out of the ground halfway up a hill. “In the little concentration of fossils, there were lots of limb bones from antelopes and horses obscuring everything else,” says Tseng, who was then a graduate student at USC and is now with the American Museum of Natural History. “It wasn’t until we started lifting things up, one by one, that we saw the top of a skull, and we thought, from the shape, that it looked something like a cat.”
After a few years of analysis, Tseng’s team has discovered that the skull doesn’t belong to any old cat. As they’ve documented in a study published today in Proceedings of the Royal Society B, the skull and six associated fossilized jawbone fragments are the first evidence of a newly discovered species, which they’ve called Panthera blytheae. The discovery represents the oldest “big cat” (a group that includes large predatory cats like lions, jaguars, tigers and leopards) ever found by a wide margin.
The sediments that make up the basin as a whole range from 6 million to 400,000 years in age, so the group dated the fossil by analyzing the age of the particular rock layers it was buried in. This involved using techniques of magnetostratigraphy, in which scientists analyze the magnetic orientation of the rocks and compare it to known reversals of the Earth’s magnetic field. This method can only provide rough estimates for an item’s age, but it revealed that the skull is between 4.10 and 5.95 million years old. Previously, the oldest known big cat fossils—a number of tooth fragments found in Tanzania—were 3.6 million years old.
The new find fills a gap in the evolutionary record of big cats. By analyzing the DNA of living species, scientists had previously estimated that big cats had split from the Felinae subfamily—which includes smaller wild cats, like cougars, lynxes, along with domestic cats—about 6.37 million years ago. The very existence of P. blytheae confirms that the split happened prior to when this big cat roamed.
But how much earlier? The find could suggest, Tsang says, that big cats branched off from smaller cats much farther back than thought. By comparing the skull’s characteristics with fossils from other extinct big cats, the anatomy of living cat species, and DNA samples taken from both living cats and a few recently extinct, Ice Age-era species (known as cave lions), the researchers assembled a new evolutionary family tree for all big cats. Using known rates of anatomical changes over time and the observed anatomy of P. blytheae, they projected backwards, and estimated that the earliest big cats likely branched off from the Felinae subfamily between 10 and 11 million years ago.
The new fossil also solves a geological mystery. Previously, using DNA analysis of all living big cats and mapping the the fossils excavated from various sites around the world, researchers had determined it was most likely that their common ancestor had lived in Asia. The oldest known specimens, however, were found in Africa. The new species provides the first direct evidence that central Asia was indeed the big cats’ ancestral home, at least as far back as the current fossil record currently goes.
From the fragmented fossils, it’s hard to know much about the extinct species’ behavior and lifestyle, but the researchers were able to make some basic extrapolations from the skull’s anatomy. “It’s not a huge cat, like a lion or a tiger, but closer to a leopard,” Tsang says. The creature’s habitat was likely similar to the current Tibetan plateau, so Tseng speculates that, like the snow leopards that currently live in the area, this species did not hunt on the open plains, but rather cliffs and valleys. Tooth wear patterns also suggest similarities with current snow leopards—the rear teeth, likely used for cutting soft tissue, remain sharp, whereas the front teeth are heavily worn, perhaps reflecting their use in prying open carcasses and picking meat off bones.
Tseng says that he and colleagues plan to return to the area to search for more fossils that could help enlighten us on the evolutionary history of big cats. “The gap still isn’t completely filled yet,” he says. “We need to find older big cats to put the picture together.”
November 6, 2013
New species of insects, worms and other creepy-crawlers are announced on a monthly basis. Similarly, just last week, two new humpback dolphin species splashed into the headlines. And in October, news broke that early humans may have included fewer species than previously thought. This forces the question: what does it take to be a distinct species?
More than 70 official species definitions exist, of which 48 are widely accepted and used by scientists. And there’s no hard rule that scientists must stick to just one definition; some apply a handful of species definitions when approaching the topic. “I personally go to my lab every day and use five species definitions to conduct research,” says Sergios-Orestis Kolokotronis, a molecular ecologist at Fordham University, and co-author of the new dolphin study, published in Molecular Ecology. “And I sleep just fine amidst this uncertainty.”
Species definitions oftentimes do not translate from one organism to another. Dolphins may become isolated by distance and behavior that prevents them from reproducing, but in other cases–such as bacteria, which reproduce asexually–these distinguishing markers do not apply. Thus, the definition of what constitutes a species varies depending on whether scientists are studying dolphins, monkeys, insects, jellyfish, plants, fungi, bacteria, viruses or other organisms, Kolokotronis explains. And likewise, methods for investigating those species also vary. “Whoever figures out THE unifying species definition across the Domains of Life gets the Crafoord Prize!” Kolokotronis jokes.
In the case of the four dolphin species, each occupy different sections of ocean around the world, including in the Atlantic off West Africa (Sousa teuszii), in the central to western Indo-Pacific (Sousa plumbea), in the eastern Indian and western Pacific (Sousa chinensis) and in northern Australia (researchers are in the process of working on a name for that one–Sousa bazinga, anyone?).
While the humpback dolphins look quite similar, their genetics tells a different story. Researchers collected 235 tissue samples and 180 skulls throughout the animals’ distribution, representing the biggest dataset assembled to date for the animals. The team analyzed mitochondrial and nuclear DNA from the tissue, which revealed significant variations between those four populations. They also compared the skulls for morphological differences.
Although the line between species, sub-species and populations is a blurry one, in this case, the researchers are confident that the four dolphins are divergent enough to warrant the “species” title. The mitochondrial DNA turned up genetic signatures distinct enough to signal a separate species, and likewise, differences in the dolphins skulls supported this divergence. Although the nuclear DNA provided a slightly more confounding picture, it still clearly showed differences between the four species.
“We can confidently say that such strong divergence means these populations are demographically and evolutionarily isolated,” says Martin Mendez, a molecular ecologist at the American Museum of Natural History and lead author of the dolphin paper. “The key is that all the evidence–mitochondrial DNA, nuclear DNA and morphology–exhibited concordant patterns of distinct units,” he continues, which are “usually a must for species proposals.”
The genetic data the team collected does not have enough resolution to reveal how long ago the humpback dolphins diverged, and the team has yet to examine the drivers that fueled those speciation events. But Mendez and his colleagues have found that, in some dolphin populations, environmental factors such as currents and temperature play a role in separating populations and encouraging speciation. Different behaviors can help reinforce that separation, too. Most likely, however, geographic isolation plays a significant role in this case. “For populations living a couple hundred kilometers from one another, it’s perfectly possible for them to meet,” Mendez says. “But the distance from Africa to Australia is so great, it’s difficult to imagine those populations would ever be linked.”
Dolphins, Mendez and his colleagues are finding, evolve relatively quickly once isolated from parent populations. New cryptic–or hidden–species have similarly turned up in waters near South America. There may very well be other species of dolphins–or any type of animal, in fact–lurking undetected within an already-discovered species. ”This really applies to most taxa,” Mendez says. Across the board, “we’re adding many more species by looking at genetic data.”
While cryptic species almost certainly await discovery and will increase the head-counts of some organisms, in the case of ancient human ancestors, on the other hand, researchers now suspect that we’ve been too quick to pull the species card. An extremely well-preserved, approximately 1.8 million year-old Homo erectus skull discovered in Georgia alerted scientists to the potential revision. The skull’s odd proportions–large, but with a small brain case–prompted researchers to analyze variation between modern human and chimpanzee skulls, and compare those variations with other known human ancestor species. As the Guardian reports:
They concluded that the variation among them was no greater than that seen at Dmanisi. Rather than being separate species, the human ancestors found in Africa from the same period may simply be normal variants of H erectus.
If the scientists are right, it would trim the base of the human evolutionary tree and spell the end for names such as H rudolfensis, H gautengensis, H ergaster and possibly H habilis.
Ancient humans, of course, are no longer around for us to study their behaviors and mating tendencies, so anatomy has to do. For now, researchers are calling for more specimens to determine where that line will fall.
The line distinguishing two species may be a fuzzy one, but in the case of the dolphins, it is a big deal in terms of conservation. Australia, for example, is planning to design protective legislation for its new dolphin species, and Mendez hopes other countries will do the same.
Nonetheless, pondering the speciation of humans in dolphins in light of these two findings raises lots of questions: Are we fractally subdividing genetic information and brain cavity size to group and regroup organisms, or is there vast genetic diversity in even familiar species that we’ve yet to uncover? What does it mean for a species to gain or lose members of its family tree? The world and its organisms await more research.
October 10, 2013
In genetics, it’s not just the living who advance the field: DNA preserved in the brittle bones of our ancestors can provide significant insight into our genetic history. Such is the case with a new genetic history of Europe, traced by an international team of researchers and published today in Science. By creating a seamless genetic map from 7,500 to 3,500 years ago in one geographic region, scientists discovered that the genetic diversity of modern day Europe can’t be explained by a single migration, as previously thought, but by multiple migrations coming from a range of areas in modern day Europe.
To write the genetic history of Europe is to glance into the evolution of a Western culture and, often, to be greeted with more questions than answers: Why do 45 percent of Europeans share a distinct kind mitochondrial DNA (DNA passed down through the maternal line) known as haplogroup H? What causes one type of mitochondrial DNA to become dominant over another kind? Can changes in an archaeological record mirror changes in a genetic record?
The new genetic history might provide some answers to these questions. To attempt to piece together Europe’s vast genetic history, researchers from the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, the University of Mainz, the State Heritage Museum in Halle (Germany), and National Geographic Society’s Genographic Project extracted mitochondrial DNA from the teeth and bones of 396 prehistoric skeletons. These skeletons were found in a rather small and confined area within the German state of Saxony-Anhalt, an area which in previous studies had proved to hold a number of usable skeletal samples.
“We collected over 400 samples from skeletal individuals and extracted DNA. And for 396 of them, we got unambiguous results that could be confirmed,” says Dr. Wolfgang Haak of ACAD, a
lead author of the study. “DNA is not preserved in all individuals, so that was a fantastic success rate.”
The study included a wealth of data not seen before
–ten times as much mitochondrial DNA was examined as in previous studies, making it the largest examination of ancient DNA to date. Such a large amount of data allowed the researchers to create a “a gapless record…from the earliest farmers to the early Bronze Age,” says Haak in a press statement.
One of the ways researchers were able to piece together this gapless genetic record was by narrowing their skeletal samples to a single region. The region in Saxony-Anhalt is especially fruitful when it comes to ancient skeletal samples due to recent political history: after the Berlin Wall was torn down, part of former East Germany underwent a tremendous amount of infrastructural revitalization. In the process of digging new roads and motorways, a number of ancient skeletons were uncovered, boosting the archeological record so much that researchers have access to a sample of specimens ranging from 7,500 years ago to present-day. Moreover, by confining their search within distinct geographic parameters, the researchers were able to construct a real transect of what happened through time in a specific place, instead of a “patchy record of here and there,” as Haak describes the alternative.
What they found surprised them. In an earlier study, Haak and his colleagues used ancient DNA to show that lifestyles in Central Europe switched from hunting and gathering to farming around 5,500 BCE soon after a wave of migration from the Near East, evidenced
by a visible change in the genetic makeup when farming enters the archeological record. But the genetic diversity of modern Europe is too complex to be explained by this migration event alone.
The conundrum that left Haak and researchers puzzled–until now. By taking samples from specimens that create a complete timeline in Saxony-Anhalt, the researchers could pinpoint when changes within the mitochondrial DNA occurred. Confirming their past finding, they saw that while the DNA patterns changed with the influx of farming, they also changed thousands of years later.
By comparing the timing of these genetic changes with a timeline of archaeological finds in central Europe, and by looking up the cultural origins of new artifacts that pop up in the timeline when these genetic changes happened, researchers suggest that the genetic history of Europeans was not only affected by a migration of farmers from the Near East, but by subsequent migrations from cultures in to the west (what is now the Iberian Peninsula) and east (what is now Latvia, Lithuania, the Czech Republic and other modern Eastern European countries).
“With this genetic timeline, we can confirm that the first genetic change occurred between hunter-gatherers and farmers, and it’s surprisingly stable for about two thousand years, when farming is completely established,” Haak explains. “Then, towards the end of the Neolithic, we gain a bit of momentum and see a bunch of early hunter-gatherer lineages coming back. And then again, shortly after that, we see new impulses, coming both from the East and the West. There are suddenly these additionally elements that make-up most of the modern-day diversity. By the time that we reach the early Bronze Age, we have mostly everything in place that we see today.”
The authors’ hypotheses on where these waves of migrations came from relies on the idea that new cultural artifacts, if found in a specific region, must have been brought by travelers far away. But new tools and artifacts, by themselves, don’t automatically mean that migrations have happened to freshen the gene pool: as Haak notes, just because one uses an iPod does not make one distinctly American, or European, or anything else. Nonetheless it seems that, at least in ancient times, new tools and technologies might have gone hand in hand with genetic influxes as migrants brought old techniques to their new lands.
August 21, 2013
As the inane car insurance commercials suggest, ancient humans were smarter than we give them credit for. They created some of the same words we still use today. They even brewed beer.
Now evidence suggests that they had some culinary flair as well. A new analysis of food residue encrusted on millennia-old pottery shards collected from sites in Germany and Denmark shows that prehistoric humans used the spice mustard seed to season the plant and animal staples that made up the bulk of their diet.
As part of the new study, published today in PLOS ONE, researchers from the UK’s University of York and elsewhere chemically analyzed the residue on ancient pieces of pottery that are part of the collections of a trio of museums—the Kalunborg and Holbæk Museums, in Denmark, along with the Schleswig-Holstein Museum in Germany. The artifacts were originally excavated from three different sites in the same two countries which are between 5,750 and 6,100 years old, an era during which people in the area were in the midst of transitioning from hunter-gatherer to nomadic societies.
When analyzing the food gunk encrusted on the pottery, the team looked specifically at phytoliths, microscopic granules of silica that plants produce and store in their cells after absorbing silicic acid from the soil. Different plants produce slightly different types of phytoliths, so by closely examining them, the scientists were able to figure out which sorts of plants had been cooked in the pottery.
They found that the residue from the insides of the pots had much larger quantities of phytoliths than the outsides, confirming that the granules were indicative of cooking use. When they compared the size and shape of the phytoliths to databases of hundreds of modern plant phytoliths, they most closely matched that of mustard seed. The team also found oil residue from both land animals and marine life, and other plant residues that come from starchier plants—suggesting that these prehistoric people were cooking fish, meat and plants in the pots and seasoning them with the mustard seed.
For the scientists, the most surprising aspect of the find is the pots’ age. Until now, the oldest clear evidence for spice use was the discovery of residue from ginger and turmeric in 4,500-year-old cooking pots linked to the Harappa culture, in Northern India. But the new find shows that humans were using spices more than 1,000 years earlier.
In Northern Europe, this was a time soon after domestic animals, such as goats and cattle, were introduced, dramatically remaking these societies’ lifestyles. Still, at this point, crops were not known to have been domesticated—these people were still centuries away from the fully settled agricultural societies that would eventually dominate.
Previously, experts thought that the use of plants in cooking during this era was solely motivated by a need for calories. But the presence of mustard seed, which provides essentially no caloric or nutritional value, indicates that these prehistoric people valued taste as much as we do.