Thursday, February 12, 2009

Cucumbers & Morning Sickness by Design

Cucumbers must have some highly toxic components because they continue to be a food that smells absolutely disgusting to me. Unfortunately, someone who sits near me at work loves them. Fortunately though, the scent aversion is all part of the mind's design — a pregnant mind.

Morning sickness, or rather pregnancy sickness for it truly occurs at any time of day, appears to be a bona fide adaption in an evolutionary sense. It's adaptive, meaning it is helpful for us as a species, but more than that, it is an adaption — a mechanism with enough complexity, precision, and efficiency to indicate a functional design.

Long, long, long before I ever became pregnant I read Margie Profet's landmark research on the evolutionary significance of morning sickness and was impressed enough to remember that although it is seriously annoying — it is actually a very good thing to experience while pregnant. It means the baby has a higher chance of being healthy and a lower chance of miscarriage.

What I didn't recall, until I recently reread the paper, is that the evidence is actually quite impressive. I also learned that the author herself is impressive. Having never formally studied biology or evolution and with only a BA degree — and a brain — she scored a $250,000 MacArthur Foundation Genius Grant to study the phenomenon. Freaking awesome! And jealous! I could have spared myself all those wasted years slaving away in grad school... grrrr. However, they did land me a couple of killer teaching positions!

So, McGenus Profet accumulated the evidence that showed that the nausea, food and scent aversions, and vomiting associated with the First Trimester of pregnancy represent an adaption. Previously, it had been thought that it was all a sickness, a side effect of pregnancy hormones with no benefits, only costs. And, those costs are significant. Women who experience pregnancy sickness can experience weight loss and inadequate nutrition from avoiding and/or throwing up nutritious though unpalatable foods. But there is a method behind the months of madness.

Evidence pregnancy sickness is an adaption
  • Many foods contain compounds that can produce malformations, sometimes fatal ones, in developing embryos.
  • Women who have pregnancy sickness selectively avoid foods that indicate those toxic components are present.
  • The onset of pregnancy sickness coincides with the time the embryo becomes vulnerable to the toxins.
  • Pregnancy sickness ends when the embryo's need for calories for growth outweighs its vulnerability to the toxins.
  • Changes in the olfactory system of a woman who has pregnancy sickness cause her to avoid substances with those toxins. Basically, a more sensitive sense of smell and lowered threshold for finding scents disgusting help a woman avoid foods that could harm the developing baby.
  • Finally, and most important for establishing pregnancy sickness is adaptive, women who experience moderate to severe pregnancy sickness have greater pregnancy success rates.
Cool beans if you ask me! The part I forgot was the 'sickness' ending when the fetus isn't as vulnerable as it is hungry.

So the list of no-go foods? The article pointed out that celery, cabbage, cauliflower, brussels sprouts, bananas, oranges, apples, potatoes, soybeans, black pepper, cocoa and nutmeg (among lots of other foods, especially green, leafy veggies) all have compounds that are known carcinogens. Although they are in small enough quantities to be safe for adult consumption, they are harmful to a fetus.

So glad, in way, to have experienced the morning sickness phenomenon! Equally glad, if not more so, that it is going away!!

4 comments:

The Empty Envelope said...

That is amazing.

Cecile/DreamCreateRepeat said...

I had four pregnancies and 3 healthy babies. The only time I DID NOT have morning sickness was the pregnancy that ended in miscarriage. : (

So, keep your spirits up while you vomit! ; ) All's well that ends well!

Interesting about the veges and fetuses....

JLK said...

Though I'm not arguing with the premise of the study, I feel like it doesn't entirely make sense because I think two different concepts are being lumped together here.

Morning sickness and food aversions are supposed to be two different things, with morning sickness generally only occuring during the first trimester and food aversions lasting throughout the pregnancy.

As I understand it, morning sickness generally occurs regardless of the foods a pregnant woman has ingested, though some can undoubtedly make it worse. I'm willing to accept the toxins explanation here if the body is going for the "better safe than sorry" approach.

But food aversions seem to be a different matter. Pregnant women's aversions cover the entire spectrum of foods - many of which are harmless, and they take place after the proposed toxin vulnerability time period. I don't doubt that food aversions have a basis in survival mechanisms, but I don't think toxins have anything to do with it.

I would consider food aversions to be more in line with pregnancy food cravings which also show more individual differences than commonality among pregnant women. The assumption seems to have always been that the pregnant brain is telling the mom what the baby needs. It seems reasonable then to also assume that food aversions are the pregnant brain telling the mom what the baby doesn't need, not necessarily alerting her to possible toxins in the food.

There is too much variation for one explanation to adequately cover both phenomena.

MikeM said...

Thought you might find this of interest:

Margie Profet's Unfinished Symphony
A Promising Scientist Vanishes Without a Trace
A Weekly Scientist Exclusive Report
http://www.weeklyscientist.com