Coming in late summer — human baby season

There is definitely a seasonality to human births, writes Beth Skwarecki at Double X Science. The complicated bit is that human baby season isn't necessarily the same (or as strongly expressed) from place to place and culture to culture. In the United States, significantly more babies are born in July, August, and September. Meanwhile, in Europe, babies seem to make their way into the world in spring. So there's clearly a cultural component to this — but culture doesn't explain it, entirely. Skwarecki's piece explores a messy place where culture, genetics, and circadian rhythms intersect.

The science of flu season

Flu season is in winter. Okay, great. But why? (Consider this an open thread for all your favorite humidifier recommendations.)

Happy Spring!

It's the first day of Spring! To celebrate, here is a photo that science journalist Maryn McKenna took of her car windshield in Atlanta, Georgia, coated with a single day's worth of pollen. Please file "tree bukkake" under "Things I Do Not Miss About the South".

Interesting science side note on this: It's pretty well-documented that climate changes are affecting pollen production, pollen exposure, and allergies.

USDA scientist Lewis Ziska, among other researchers, has found that ragweed is one of the plants whose growth is most enhanced by exposure to higher concentrations of carbon dioxide. Not only does the ragweed grow faster when exposed to more CO2, it also produces more pollen. This is especially an issue in cities, which have higher concentrations of CO2 than rural areas, thanks to having a higher concentration of cars and other CO2 emitting sources. Extra bonus: There's also some evidence that allergy seasons are getting longer, as Spring starts earlier and Winter takes longer to truly set in.

You can read more about this in the report from the IPCC's Working Group II and in a paper on the effects of climate change on health written by Ziska and his collaborator, the late Paul Epstein.

How seasonal affective disorder works

Winter is coming. And Scientific American's Bora Zivkovik has a detailed explanation of the biological basics behind seasonal affective disorder.