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Beef's big impact on Earth

Nature volume 511, page 511 (31 July 2014) | Download Citation

Nature's roundup of the papers and issues gaining traction on social media.

Based on data from Altmetric is supported by Macmillan Science and Education, which owns Nature Publishing Group.

Beef is suddenly big on social media, thanks to two recent papers investigating the global effects of livestock farming. Researchers are also buzzing about the mystery of vanishing clinical-trial results, and a humorous take on academic life.

Two papers make the case that beef production has a bigger impact on greenhouse-gas emissions and on the use of nitrogen and water than does the production of pork and poultry, for instance. Tim Thomson, a physician and molecular biologist at the Molecular Biology Institute of Barcelona, tweeted: “Do not imitate Americans: Eat less beef and you will mitigate environmental costs of diet.” But Jared Decker, a beef-cattle geneticist at the University of Missouri in Columbia, tweeted that cattle have a relatively small carbon footprint compared to other industry sectors, adding: “Wouldn't changing transportation & energy be more important?”

The bad news for beef came from several directions. A paper in the journal Climatic Change concluded that beef and dairy cattle account for 74% of global greenhouse-gas emissions from livestock. One of the authors, climate scientist Ken Caldeira at the Carnegie Institution for Science in Stanford, California, used Twitter to share another take on the data: “Eating beef heats the Earth 10 times more than eating chicken or pork.”

Reached for further comment, Caldeira agreed that the emissions from industry and energy dwarf those from livestock agriculture. “If the global energy system did not use the sky as a sewer, we would not be overly concerned about greenhouse-gas emissions from the agricultural sector,” he said. Still, he added, the finding that beef is less climate-friendly than chicken or pork suggests a concrete action that people can easily take. And that, Caldeira says, could explain why his tweets on this topic were among his most retweeted. “Papers seem to resonate when the problem is simple and understandable, and when the conclusions are simple and clear.”

Another study concluded that producing beef uses 28 times more land and 11 times more irrigation water than eggs, poultry, pork and dairy production. It also creates six times as much nitrogen pollution per calorie consumed in the United States. “Beef: it may taste great but it's awful for the environment,” tweeted Conor McGowan, a wildlife biologist at Auburn University in Alabama.

In a follow-up interview, Decker stood up for beef. He cited a 2002 Nature review by Jared Diamond, which suggested that we owe at least some of our success as a species to the domestication of animals, including cattle. But Decker also hopes that the latest round of research will spur changes in farming methods, including refinements to feeding practices and genetics to reduce the environmental footprint of beef production. Compared with other types of livestock farming, “the beef industry has been slower to adopt new technologies,” he said. “That needs to change.”

Caro, D., Davis S. J., Bastianoni, S. & Caldeira, K. Climatic Change (2014)

Eshel, G., Shepon, A., Makov, T., & Milo, R. Proc. Natl Acad. Sci. USA (2014)

Researchers on social media never seem to tire of discussing shortcomings in the clinical-trial system. Lately, much of the talk centred on a paper that investigated 400 randomly selected US clinical trials. All of the studies had been designated as 'completed' for at least four years, but only 70.5% had published results in any journal or on the website The other 29.5% of trials were essentially invisible to the world. The results of industry-funded studies were about half as likely as other studies to be published, the analysis found. Mark Fleury, associate director of science policy at the American Association for Cancer Research, tweeted: “Need this data in public sphere!”

A 1998 abstract entitled 'Directed evolution of a full professor' is making the rounds online again — a reminder of the scientific importance of a good laugh. The spoof abstract, written by molecular biologists Karen Ottemann and Sharon Doyle at the University of California at Berkeley, describes an attempt to grow successful professors in the lab. First author 'A. L. Nighter' and colleagues reported subjecting a group of “graduate student clones” to “several rounds of random mutagenesis followed by selection on minimal money media”. The surviving clones who could “work for long hours with vending machine snacks as a sole carbon source” were labelled 'postdocs'. Eventually, full professors were identified by their “propensity to talk incessantly about their own research” and their “inability to judge” how much time it should take to complete bench work. The abstract gained new attention this month when Jonathan Eisen, an evolutionary biologist at the University of California, Davis, tweeted it to his nearly 24,000 followers without revealing when the abstract was published. “I decided not to comment on the date,” he explained in a later tweet, “since it was still great.”

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