By studying the way it has mutated and changed over time, scientists can trace human mitochondrial DNA — the DNA that is passed from mother to daughter — back to a single woman. Basically, everybody alive is descended from her. But that's not the same thing as saying that Mitochondrial Eve was once the only woman alive. In a very nice piece — with helpful illustrations — the Christian (but evolution-accepting) scientists at BioLogos explain what Mitochondrial Eve really means and why she can't be used as an argument for creationism
. Whether or not you've ever found yourself arguing this point with a family member or friend, the piece is really useful for deepening your understanding of a pop-science concept that's often thrown around without a clear explanation behind it. — Maggie
There are two answers here: One for the legitimately curious, and one for people who want a disaster to be a referendum on climate change.
Read the rest
The New York Times Sunday Review had an article this week linking autism with the hygiene hypothesis. Written by Moises Velasquez-Manoff, the piece is part of the Times' opinion coverage, not reported news. It was also one of those sort of stories that comes across as highly persuasive ... until you start looking at the details. About halfway through reading it yesterday, it occurred to me that Velasquez-Manoff was making a lot of big statements—"perhaps 1/3 of autism, and very likely more, looks like a type of inflammatory disease", for example—without citing the sources to back those statements up.
That's easy to do when you're writing a relatively short article summarizing the contents of a much bigger book, as Velasquez-Manoff seems to be doing here. But the problems go deeper than that, according to biologist and science writer Emily Willingham. In a must-read blog post, she goes through the NYT piece and points out many flaws in argument and detail. The main problem, though, is a pretty simple one: Moises Velasquez-Manoff presents what seems to be a largely speculative hypothesis as sure-fire truth. To make that case as persuasive as it is, he leaves out lots of evidence that doesn't match up with his thesis.
Read the rest
Over at Download the Universe, Ars Technica science editor John Timmer reviews a science ebook whose science leaves something to be desired.
Read the rest
Irradiating food doesn't make it radioactive, and it does kill dangerous bacteria, like the E.coli that killed many Europeans this summer. But it's also not a panacea against food poisoning and it's definitely not the most popular idea ever thought up. In a column in the New York Times, Mark Bittman examines the evidence behind irradiation, and how that evidence does and doesn't get considered in the choices we make about food.
When it comes to irradiation, you might need a primer. (I did.) Simply put, irradiation — first approved by the FDA in 1963 to control insects in wheat and flour — kills pathogens in food by passing radiation through it. It doesn’t make the food radioactive any more than passing X-rays through your body makes you radioactive; it just causes changes in the food. Proponents say those changes are beneficial: like killing E. coli or salmonella bacteria. Opponents say they’re harmful: like destroying nutrients or creating damaging free radicals.
Many people are virulently for or against. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, says that irradiation “could do for food what pasteurization has done for milk.” (The main difference between irradiation and pasteurization is the source of the energy used to kill microbes.) Wenonah Hauter, the executive director of Food & Water Watch — which calls irradiation “a gross failure” — told me it was “expensive and impractical, a band-aid on the real problems with our food system.”
There are a few people in the middle. Former assistant secretary of the Department of Agriculture (USDA) Carol Tucker-Foreman is mostly anti-, but said that if she ran a nursing home or a children’s hospital — a place where people with weaker-than-average immune systems were cared for — it “might be something I wanted to do.” Marion Nestle, a New York University nutrition professor and the author of “Safe Food: The Politics of Food Safety” (and a food-movement icon), allows that “the bottom line is that it works pretty well if done right, and I’m not aware of any credible evidence that it does any worse harm to foods than cooking. But it isn’t always done right, and foods can become re-contaminated after irradiation.”
Via Andy Revkin
Image: NAM - Nabob Irradiated Coffee, a Creative Commons Attribution Share-Alike (2.0) image from lifeontheedge's photostream
The National Breast Cancer Coalition has come out with new evidence-based position statements regarding several popular preventative and treatment options for breast cancer. Among the findings: There is no link between abortion and breast cancer
; there's no evidence that breast self-exams actually do anything useful
; and the policy of routine mammograms for every woman doesn't help as much as we think it does