Altitude babies and epigenetics
Steve Magness has a fascinating post on his blog about a neat new study in the January issue of Journal of Applied Physiology. The researchers took a bunch of rats whose ancestors have been living at the Bolivian Institute for Altitude Biology, which is 3,600 metres above sea level. Half the rats were placed in a room with “enhanced oxygen” to mimic sea level from one day before birth to 15 days after birth; the other half simply grew up normally at 3,600 metres. Then the researchers followed the rats for the rest of their lives to see whether this “postnatal” exposure to low oxygen affected the rats’ development.
This study fits into the recent burst of research into epigenetics — the idea that early environmental influences can produce lasting changes in gene expression. And sure enough, there were significant differences between the rats who grew up at high altitude continuously (HACont) and those who got two weeks of sea-level oxygen (HApNorm):
As you can see, the high-altitude rats had higher hemoglobin and hematocrit long after the two-week exposure period (32 weeks is roughly middle-aged in rats). Among many other differences, the altitude babies also had a bigger heart, and used less oxygen. All of this sounds pretty good for endurance athletes — which is why Steve wrote:
I always joke with my friends that whenever I have kids, I’m going to stick them at altitude during pregnancy and right after just to develop super altitude adapted kids…
But there’s a caveat. Here’s the survival data for the two types of rat:
In fact, the researchers make the overall conclusion that low oxygen levels in the crucial weeks after birth are a bad thing:
We conclude that exposure to ambient hypoxia during postnatal development in [high altitude] rats has deleterious consequences on acclimatization to hypoxia as adults.
So you have to be careful what you wish for your kids. Either way, though, it’s clear that environment alone can produce profound, lifelong changes in physiology — producing group traits that we once might have mistakenly attributed to genetics.