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Microbiome musings

The January 11, 2014, issue of Science News focused on the microbiome, the diverse collection of microbes that reside in and on humans and other organisms.

Mark Bach looks forward to seeing what scientists can learn from the study of these tiny hitchhikers. “As our understanding of the microbial world — or more correctly, the world that we share with microbes — expands, we need to be ready to accept the unexpected,” he wrote in an e-mail. “Surprises await us all!” Online commenter Steve Foster called “Microscopic menagerie” (SN: 1/11/14, p. 14) “fascinating” and suggested additional reading: “Perhaps readers would also enjoy rereading Lynn Margulis’Symbiotic Planet; such a review would help provide context to such newer reports as this one.”

Tina Hesman Saey’s story about testing her own microbiome inspired a change of heart in Mark Mailloux. “I read your magazine from cover to cover,” he e-mailed, “but I confess that I am much more interested in physics and astronomy than biology topics. I often get MEGO syndrome (My Eyes Glaze Over) in biology articles — until I came across “Me and my microbiome” (SN: 1/11/14, p. 28). All of a sudden it became real. Results from an actual person (not a labful of genetically weird rats) captured my attention. I look forward to updates from her as results come in from these studies trying to find out what ‘normal’ is and how she fits in.” 


The number name game

In “The vast virome” (SN: 1/11/14, p. 18), Tina Hesman Saey noted that humans share the planet with 10 quintillion, or 1031, virus particles.

Reader ms questioned this figure on the SN website. “In America, a quintillion is 1018, not 1030 as it is in Britain. So, when you claim that there are 10 quintillion virus particles on our planet, and then say the number is 1 followed by 31 zeroes, is that because you’ve incorrectly converted an American quintillion with the British definition?

Saey explains: “The reader is correct that we meant nonillion, not quintillion. There are two systems for naming big numbers: the short scale and the long scale. The long scale was invented in the late 15th century in France and gives a new name to every number one million times bigger than the previous number. So one million million is a billion (1012), a million billion is a trillion (1018) and so on (see table, left). The long scale is used in Europe and Latin America, but no longer in the United Kingdom — though it is still often called the British system.

French mathematicians in the 17th century decided to assign names to every number one thousand times greater than the last, so a billion is 1,000 million or 109, and a trillion is 1,000 billion (1012). This short scale is the convention in the United States. The United Kingdom switched to the short scale in 1974, although France had reverted back to the long scale in 1948. Science News, published in the United States, should have said 10 nonillion viruslike particles.”


Lamarckism not quite revived

Laura Sanders described mice passing on the fear of a smell to their offspring in “Fear can be inherited” (SN: 1/11/14, p. 13).

“Isn’t that Lamarckian evolution?” e-mailed Paul Hyer. Not exactly, Sanders says. “In the early 1800s, before genes were found to carry heritable information, French naturalist Jean-Baptiste Lamarck argued that environmental influences can shape an animal and its descendants inspecific ways. 

Epigenetics, in which the environment changes gene behavior without altering the genes themselves, has given a glimmer of hope to die-hard Lamarckians. Epigenetics does allow traits acquired during an organism’s lifetime to be passed on to offspring. Because epigenetic changes can affect many aspects of an organism, the process boosts genetic variation overall, but does not promote specific changes as Lamarck might have argued. Those variations then become fodder for natural selection to act on.”

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