Your DNA tries to prepare you for cold and swimsuit season
While the DNA in your cells is more or less written out at birth, it’s not a totally static set of instructions. Just because the genes are there doesn’t mean they’re always being expressed to build proteins on a daily basis. In fact, it looks like some systems in your body are actually tailoring their activity to seasonal conditions in your environment to best match the challenges most likely to be encountered in rain or in shine.
Looking across data from people in six countries with varying latitude and climates, a number of trends emerged tied to the local climate at the time of year the DNA was sampled. In the winter, people were more likely to have stronger immune responses, with more inflammation of tissues, presumably to help fight disease and infection. Even in a country like Gambia, which doesn’t have much of a winter to speak of, there was a seasonal adjustment of the immune system. It wasn’t tied to winter, but to the rainy season, when mosquitoes and malaria would be of greater concern. In the summer, people’s bodies seemed more primed to burn winter’s fat and retain water to cope with heat.
Despite some clear patterns, researchers haven’t figured out what triggers these shifts yet. It could be shifts in diet or possibly the number of hours of daylight a person is exposed to. Once that’s found, it may help people explain or control autoimmune problems. There’s a chance that a misalignment of the immune system is at play, where your genes are prepping the immune system despite your climate-controlled lifestyle making that less necessary.
Source: Your DNA Changes With the Seasons, Just Like the Weather by Nick Stockton, Wired