Last fall, a 96-year-old man named Ramajit Raghav became a father. No woman could become a mother at 96, or even 76. That’s because women typically lose the capacity to have children around the age 50–not because they become decrepit, not because civilization has poisoned them, but because they undergo a distinct biological transition, known as menopause.

Scientists have debated for years about why menopause exists. Some have argued that it’s a trait that evolved through natural selection in our ancestors. Women who stopped reproducing ended up with more descendants than women who didn’t. Some scientists proposed that older mothers were better off putting all their effort into caring for their children who were already born, rather than having new ones. As their limited supply of eggs deteriorated, they faced a higher risk of miscarriages and even death during childbirth. (In terms of reproduction, men have it easy by comparison: they can make new sperm through their whole life and don’t have to suffer any of the risks of pregnancy.)

Continue reading “Why Menopause?” →

The ancient Greeks believed that the constellation Gemini represented the twin horsemen Castor and Pollux. According to one version of the story, Castor was an ordinary human, while Pollux, the son of Zeus, lived forever. Castor was mortally wounded during a battle, whereupon Zeus offered Pollux a choice: he could let Castor die or he could give his brother half his immortality. Pollux chose to save his brother, and forever afterwards they would spend a day Olympus followed by a day in Hades.

“My twin brother died from suicide in 2011,” writes Zach Poynter. He chose to memorialize his brother with two tattoos on his arm. One is of the constellation Gemini. The other is of DNA. “We were identical twins, thus sharing the same DNA (although not expressing it the same way!)” Poynter writes.

You can read about the science of that paradox here and here. And you can see the rest of the Science Tattoo Emporium here or in my book, Science Ink: Tattoos of the Science Obsessed.

Originally published April 14, 2013. Copyright 2013 Carl Zimmer.

For the past few years I’ve been a judge for the Imagine Science Film Festival. One of my favorites from last year is called The Centrifuge Brain Project; I was so delighted by it that I went hunting for it online to share here. For whatever reason, it didn’t show up until recently. You can now watch it on Vimeo, and I’ve embedded it below.

The Centrifuge Brain Project from Till Nowak on Vimeo.

I have complicated feelings about movies about science. I don’t like movies that come after you with a pedagogical cudgel. To me, the best movies are the ones that take the most liberties with science. I guess I like The Centrifuge Brain Project so much because it toys with science in such a deadpan way–so deadpan that some commenters at Vimeo asked if the crazy amusement park rides were real or not. And yet, in the end, it’s not a simplistic joke, but a short meditation on how we humans try to fight gravity–and nature in general–both in the lab and at amusement parks.

(Mark your calendars–the next Imagine Science Film Festival will be coming to New York this October.)

Originally published April 11, 2013. Copyright 2013 Carl Zimmer.

Let’s say you want to buy things with germs in them. There’s yogurt, of course, but there’s so much else.

You can buy pills for your gut, creams for your face, tablets for your breath. You can buy blueberry juice with germs, and pizza with germs. And a lot of these products make big promises about the benefits their germs will bring you. “Fungal Defense is specially formulated with ingredients that help maintain a balanced, healthy digestive environment,” for example. Natren Natasha’s Probiotic Face Cream “is enriched with DNA fragments of beneficial bacterial cells, which speed up the skins own natural renewal process.”

Continue reading “Bugs As Drugs” →