If you explore our genealogy back beyond about 370 million years ago, it gets fishy. Our ancestors back then were aquatic vertebrates that breathed through gills and swam with fins. Over the next twenty million years or so, our fishy ancestors were transformed into land-walking animals known as tetrapods (Latin for “four feet”).

The hardest evidence–both literally and figuratively–that we have for this transition comes from the fossil record. Over the past century, paleontologists have slowly but steadily unearthed species belong to our lineage, splitting off early in the evolution of the tetrapod body. As a result, we can see the skeletons of fish with some–but not all–of the traits that let tetrapods move around on land. (I wrote about the history of this search in my book At the Water’s Edge; for more information, I’d suggest Your Inner Fish, by Neil Shubin, who discovered Tiktaalik, one of the most important fossils on the tetrapod lineage.)

Continue reading “Evolution’s Baby Steps” →

I’ve been on something of a microbial jag recently. For my past two columns for the New York Times I’ve explored the creepy biochemical sophistication of bacteria.

First, I took a look at the outbreak of toxic bacteria that shut down Toledo’s water supply a couple weeks ago. A lot of people don’t realize it, but those microbes have been spewing out these toxins for about three billion years–for reasons that scientists are still trying to figure out.

Then I wrote about the chemicals that our own microbiome releases, and the ways they can affect our behavior. Some scientists don’t think those changes are just random side effects. Instead, our microbes may be trying to manipulate us for their own benefit, eating certain foods or getting close to other people (also known as hosts).

Check them out!

Continue reading “Microbes as Poisoners and Puppet Masters” →

I can still remember the shock I felt when I heard about fecal microbiota transplants for the first time. It is not the sort of thing you forget.

At a microbiology conference, a scientist was giving a lecture about the microbiome–the microbes that live harmlessly inside of us. She described one unusual case she was involved in where a doctor named Alexander Khorutsused the microbiome to save a patient’s life. The patient had taken antibiotics for a lung infection. While the drugs cleared that infection, they  also disrupted the ecology of her gut, allowing a life-threatening species of bacteria called Clostridium difficile to take over. The pathogen was causing horrific levels of diarrhea. Khoruts couldn’t stop it, because it was resistant to every antibiotic he tried.

So Khoruts decided to use an obscure method: the fecal transplant. He took some stool from the patient’s husband, mixed it with water, and delivered it to her large intestines like a suppository. In a matter of days she was recovering.

Continue reading “Taking the Yuck Out of Microbiome Medicine” →

Animals have been smelling for hundreds of millions of years, but the evolution of that sense is difficult to trace. You can’t ask an elephant to describe the fragrance of an acacia tree, for example, nor can you ask a lion if it gets the same feeling from a whiff of the same plant.

So scientists have to gather indirect clues to how different species use their noses. One way is to run simple tests on animals, seeing if they show an ability to tell different odors apart. Elephants, for example, can tell the difference between the smells of as many as 30 different members of their extended family.

Continue reading “The Tree of Smells” →

Some of my friends are sporting wristbands these days that keep track of their bodies. Little computers nestled in these device inside record the steps they take each day, the beats of their heart, the length of their slumbers. At the end of each day, they can sit down at a computer and look at their data arrayed across a screen like a seismogram of flesh.

I got one of these devices as a gift recently. But as much as I enjoy wasting time with technology, I just didn’t care enough to put it on my wrist. I already know that I should run more, walk more, stand more, and avoid sitting in front of monitors more. I don’t need granular data to remind me of that.

But as I read the journal Genome Biologythe journal Genome Biology today, I decided that someday I might surrender to the Quantified Self movement. I’ll just have to wait till I can track my trillions of microbes from one day to the next.

Continue reading “The Quantified Microbiome Self” →