As I’ve noted before, our bodies are riddled with microbes – there are more of them than there are of us (if you go by shear number). But where do they come from? Each individual has a complex ecosystem of commensal (harmless) microbes that live on our skin, in our nose, mouth, ears and gut, and we lay the foundations for this ecosystem at birth. According to a new study in the Proceedings of the National Accademy of Sciences (PNAS), different methods of birth (traditional vs cesarean section) have very different outcomes in terms of what bacteria end up colonizing you:

The goal of the present study was to obtain a community-wide perspective on the influence of delivery mode and body habitat on the neonate’s first microbiota[…] We found that in direct contrast to the highly differentiated communities of their mothers, neonates harbored bacterial communities that were undifferentiated across multiple body habitats, regardless of delivery mode. Our results also show that vaginally delivered infants acquired bacterial communities resembling their own mother’s vaginal microbiota, dominated by Lactobacillus, Prevotella,or Sneathia, and C-section infants harbored bacterial communities similar to those found on the skin surface, dominated by Staphylococcus, Corynebacterium, and Propionibacterium.

It’s been known for a long time that c-section babies were more prone to allergies and asthma, and there’s a strong link between commensals and the immune system, but exactly what the difference was remained obscure. Basically, what this paper shows is that the types of bacteria that get us started are established very early.

Babies born through the traditional route are very quickly exposes to the bacterial communities of their mothers – both vaginal and gut bacteria (women often defecate when giving birth). Once these bacteria get established, they fill up all the niches, and prevent other bacteria from getting a foothold. By contrast, c-section babies don’t have this initial exposure – the womb is fairly sterile, and the conditions of this surgery prevent contact with the mother’s other mucosal surfaces. Because of this, the infant is ripe for colonization from the myriad of bacteria found everywhere else, from the nurses and doctors that handle them to the bacteria on the skin on the mother’s breast when feeding.

It’s important to note that we can’t yet draw a distinct causative link between early establishment of bacterial communities and future disease (allergies, asthma etc), right now it’s just correlation. And though infants are colonized by very few types of microbes, as they develop, the microbial ecosystem diversifies into thousands or millions of different species. Researchers are hard at work using new technologies to try to figure out all the different things living in an adult gut (given the spiffy name, “the microbiome”), and we’ve barely scratched the surface.

The one thing that is clear is that the little things living in us and on us can have a profound effect on our health, and with new research, hopefully we can use that knowledge to our advantage.


From global warming to evolution to vaccine safety, the public consistently (and sometimes increasingly) doesn’t know or doesn’t believe the scientific consensus. A new piece in Wired magazine claims this is because scientists are bad at PR:

On the final day of last winter’s meeting of the American Association for the Advancement of Science, a panel convened to discuss the growing problem of climate change denial. It went poorly[…] What the scientists should have been asking was how they could reverse the problem. And the answer isn’t more science; it’s better PR[…]

“They need to make people answer the questions, What’s in it for me? How does it affect my daily life? What can I do that will make a difference? Answering these questions is what’s going to start a conversation,” Bush [CEO of a PR firm] says. “The messaging up to this point has been ‘Here are our findings. Read it and believe.’ The deniers are convincing people that the science is propaganda.”

It’s hard to argue that good PR might improve science outreach, but there are several problems with this approach. One, as the author notes, is that scientists hate the idea of “spin.” You shouldn’t have to spin good science, the evidence should speak for itself. Unfortunately, the vast majority of Americans don’t have the ability to interface directly with the evidence; most scientific journals are locked behind pay-walls, and even with access, the general public would be hard pressed to penetrate the dense, jargon-filled articles. After four years of college and several years working in biology labs, I finally started getting proficient at reading primary biology papers a year into graduate school.

Another problem: who pays for the PR? It’s all well and good for Tiger Woods to pay a professional PR firm, but scientists spend enough time writing grants for money to do experiments. And scientists are mostly decentralized, there’s no organized structure for coordinating this sort of effort even if it was desired. Maybe the government could step in, but politicians are generally scientifically illiterate, and some are in the anti-science camp themselves.

I have mixed feelings, but I think the best place to start is with education in schools. That’s more of a long term strategy though. In the short term, I’m not sure what to do, but professional PR people are probably not the answer.