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Type blood O confers resistance to malaria
This week–
COLIN BARRAS
SCRAPING the barrel can be a surprisingly productive exercise. By doing just that, marine archaeologists have pinned down exactly which commodities were traded by early European civilisations. The civilisations of two-and-ahalf millennia ago relied on trade across the Mediterranean to feed themselves. Yet despite decades studying the routes they followed, we still know “shockingly little” about their trading practices, says Brendan Foley at Woods Hole Oceanographic Institution in Massachusetts. “Before the 17th century AD, there aren’t the kinds of economic data that you need to say anything meaningful about trade,” he says. That is, in part, because archaeologists have been forced to glean most of their information on ancient trade from analysing the design of artefacts, without
any direct information on what was inside them. “Imagine trying to reconstruct the contents of a box by looking at empty containers alone,” he says. So Foley and Maria Hansson of Lund University in Sweden have come up with another way to work out what these artefacts once carried. The pair recovered fragments of DNA from the inside of ancient pots, or amphorae, collected from a 2400-year-old Mediterranean shipwreck. They then amplified the fragments using the standard polymerase chain reaction (PCR) technique, and compared the DNA sequences they contained with modern sequences in the GenBank DNA database. Archaeologists had assumed that pots in this particular style were only used to carry wine. The DNA analysis told a different story. It revealed traces of olive, thyme and oregano, leading Foley and Hansson to conclude that the amphorae carried olive oil that
Blood pressured to evolve by disease IT’S no accident of nature that human blood has split into a handful of distinct types: A, B, AB and O. People with type O blood are at less risk of dying from malaria but more vulnerable to cholera and stomach ulcers, suggesting that different diseases put different pressures on how blood evolved. Malaria has probably killed more people than any other disease in human history. The malaria parasite invades red blood cells, and some malaria strains then snare other uninfected blood cells, forming “rosettes”. 16 | NewScientist | 27 October 2007
No one knows exactly why they form, says Alexandra Rowe of the University of Edinburgh, UK. It was thought to be a way for the parasite to infect more cells, but it seems more likely that it may be a “cloaking device that hides infected cells from the immune system”, says Rowe. To form the rosettes – which cause damage by disrupting fine blood vessels – the malaria parasite uses sugars on the surface of red blood cells. People with type A or B blood have one of two kinds of these sugars on their cells while people with AB blood have both. People
THE ART ARCHIVE/ARCHAEOLOGICAL MUSEUM BARI/DAGLI ORTI
Pots reveal traces of ancient trade
–Shipping containers classical-style–
had been flavoured with herbs (Journal of Archaeological Science, DOI: 10.1016/j.jas.2007.08.009). They are now using the technique to work out what a host of other amphorae found in ancient shipwrecks contained, something that is otherwise hard for archaeologists to determine with any confidence. “There was a wreck off the Turkish coast that had amphorae
containing olive pits, but that’s unusual,” Foley says. “There is absolutely no doubt that DNA analysis has major potential to shed light on the ancient economy,” says classical archaeologist Eberhard Sauer of the University of Edinburgh, UK. “It allows us to venture into uncharted territory, and there will almost certainly be major leaps forward.” ●
with type O have neither, and this appears to make it more difficult for the disease to form rosettes. In Mali, Rowe found that children aged 3 or 4 with severe malaria were more likely to carry rosettes than children with milder malaria. Crucially, the less seriously affected children – with fewer or less-stable rosettes – were three times as likely to have type O blood as those with severe malaria (Proceedings of the National Academy of Sciences, vol 104, p 17471). “If we can develop a drug or vaccine to reduce rosetting, mimicking the effect of blood
group O, we may be able to save lives,” Rowe says. But if type O is so useful, why doesn’t everyone have it? Among people of European descent, who historically have had a lower risk of contracting malaria, less than half are type O, compared with more than half of Africans and nearly all of some Native American groups. That might be because type O blood appears to make people more susceptible to other diseases, such as stomach ulcers caused by Helicobacter and gastroenteritis caused by noroviruses. Blood type O is also the most common type in Latin America. But there, cholera victims with type O blood are eight times more likely to have a severe form of the disease than a milder version. Debora MacKenzie ●
“If we can develop a drug that mimics the effect of having blood group O, we may be able to save lives”
www.newscientist.com
COLIN BARRAS
SCRAPING the barrel can be a surprisingly productive exercise. By doing just that, marine archaeologists have pinned down exactly which commodities were traded by early European civilisations. The civilisations of two-and-ahalf millennia ago relied on trade across the Mediterranean to feed themselves. Yet despite decades studying the routes they followed, we still know “shockingly little” about their trading practices, says Brendan Foley at Woods Hole Oceanographic Institution in Massachusetts. “Before the 17th century AD, there aren’t the kinds of economic data that you need to say anything meaningful about trade,” he says. That is, in part, because archaeologists have been forced to glean most of their information on ancient trade from analysing the design of artefacts, without
any direct information on what was inside them. “Imagine trying to reconstruct the contents of a box by looking at empty containers alone,” he says. So Foley and Maria Hansson of Lund University in Sweden have come up with another way to work out what these artefacts once carried. The pair recovered fragments of DNA from the inside of ancient pots, or amphorae, collected from a 2400-year-old Mediterranean shipwreck. They then amplified the fragments using the standard polymerase chain reaction (PCR) technique, and compared the DNA sequences they contained with modern sequences in the GenBank DNA database. Archaeologists had assumed that pots in this particular style were only used to carry wine. The DNA analysis told a different story. It revealed traces of olive, thyme and oregano, leading Foley and Hansson to conclude that the amphorae carried olive oil that
Blood pressured to evolve by disease IT’S no accident of nature that human blood has split into a handful of distinct types: A, B, AB and O. People with type O blood are at less risk of dying from malaria but more vulnerable to cholera and stomach ulcers, suggesting that different diseases put different pressures on how blood evolved. Malaria has probably killed more people than any other disease in human history. The malaria parasite invades red blood cells, and some malaria strains then snare other uninfected blood cells, forming “rosettes”. 16 | NewScientist | 27 October 2007
No one knows exactly why they form, says Alexandra Rowe of the University of Edinburgh, UK. It was thought to be a way for the parasite to infect more cells, but it seems more likely that it may be a “cloaking device that hides infected cells from the immune system”, says Rowe. To form the rosettes – which cause damage by disrupting fine blood vessels – the malaria parasite uses sugars on the surface of red blood cells. People with type A or B blood have one of two kinds of these sugars on their cells while people with AB blood have both. People
THE ART ARCHIVE/ARCHAEOLOGICAL MUSEUM BARI/DAGLI ORTI
Pots reveal traces of ancient trade
–Shipping containers classical-style–
had been flavoured with herbs (Journal of Archaeological Science, DOI: 10.1016/j.jas.2007.08.009). They are now using the technique to work out what a host of other amphorae found in ancient shipwrecks contained, something that is otherwise hard for archaeologists to determine with any confidence. “There was a wreck off the Turkish coast that had amphorae
containing olive pits, but that’s unusual,” Foley says. “There is absolutely no doubt that DNA analysis has major potential to shed light on the ancient economy,” says classical archaeologist Eberhard Sauer of the University of Edinburgh, UK. “It allows us to venture into uncharted territory, and there will almost certainly be major leaps forward.” ●
with type O have neither, and this appears to make it more difficult for the disease to form rosettes. In Mali, Rowe found that children aged 3 or 4 with severe malaria were more likely to carry rosettes than children with milder malaria. Crucially, the less seriously affected children – with fewer or less-stable rosettes – were three times as likely to have type O blood as those with severe malaria (Proceedings of the National Academy of Sciences, vol 104, p 17471). “If we can develop a drug or vaccine to reduce rosetting, mimicking the effect of blood
group O, we may be able to save lives,” Rowe says. But if type O is so useful, why doesn’t everyone have it? Among people of European descent, who historically have had a lower risk of contracting malaria, less than half are type O, compared with more than half of Africans and nearly all of some Native American groups. That might be because type O blood appears to make people more susceptible to other diseases, such as stomach ulcers caused by Helicobacter and gastroenteritis caused by noroviruses. Blood type O is also the most common type in Latin America. But there, cholera victims with type O blood are eight times more likely to have a severe form of the disease than a milder version. Debora MacKenzie ●
“If we can develop a drug that mimics the effect of having blood group O, we may be able to save lives”
www.newscientist.com