My son and I just listened to a completely engrossing podcast on inheritance from RadioLab. The episode had three stories about different aspects of inheritance and genetic control. The first didn’t capture my interest nearly as much as the next two, so I won’t discuss it here.
The second story proposed and interesting idea of Lamarckean inheritance based on the extraordinary record-keeping of a far-north town in Sweden. In this town, the church kept amazingly detailed records about births, deaths, disease, health and even crop production year to year. When all these data were analyzed, researchers found a strong correlation between the availability of food to men in the village and the health and wellbeing of that man’s children. What might seem unintuitive is that contrary to what you might think, the children of men who suffered through years of starvation when they were ~9-12 years old fared the best. If dad ate well, your health prognosis was poor. If dad ate poorly, your prognosis was better. The effect even seemed to trace down two generations.
The explanation for this was that at this time in a man’s life he is making the cells that will go on to make sperm. Somehow, these cells can receive genetic imprinting that improves the fitness of the offspring.
Let me stop here. I have to say, I think this is entirely unconvincing. I can think of at least one simpler explanation for these data. Further, I can easily imagine how if it was possible to turn on these beneficial changes, evolution would make this the norm rather than the exception.
Example data. A) Population lifespan following feast years, 100% survival. B) Population lifespan following famine years, 50% survival.
Consider a population of 100 kids in the target age group during a year of ‘feast.’ 100% of these kids survive and have children. These children have an average lifespan of 50yrs. Given the same group during a year of ‘famine.’ 50% of the kids survive and have children. The children live to an average age of 75 yrs. It appears that the famine during the elder generation improved the fitness of the younger.
But, if we examine the ‘feast’ population again, we might see that they can be broken up into two natural groups, one with a 75yr lifespan (the healthier 50%) and one with a 25yr lifespan (the less healthy). If the famine year selectively kills the weaker kids, then we are simply selecting our way to better health rather than causing it.
Because this is published research I expect that this simple answer was excluded somehow and I hope to find the original work to see that, but the burden of proof rests on the group proposing the more complex explanation.
I’ll see if I can research this a little and write again later, but I wanted to comment right away because I thought that it was an interesting example of how numbers can sometimes lead you astray if you’re not careful.
Oh, and very quickly, the last story…
The last story was about a woman who had adopted a baby girl, Destiny, from a mother who was addicted to drugs and couldn’t support the child. Amazingly, the next three years after that, the same mother gave birth to three more addicted babies that were all adopted by the same family. Because of her frustration about how this woman was so casually bringing more children into the world, one a year, each addicted to heroin et al. at the time of birth, the adoptive mother tried to pass a law to somehow prevent this from happening. When that failed, she worked directly to set up a fund to pay addicted women to undergo surgical sterilization or get long term birth control.
Many saw this as eugenics in action. Personally, I see no convincing connection to eugenics whatsoever based on the fact that the procedure was voluntary and based on a behavior rather than an innate characteristic of the women. Nevertheless, the conversation went places I never expected – mostly because I thought Jad and Robert would not get drawn into such ridiculous speculations and extensions of logic as they did. It was still good listening though.
I highly recommend checking out this episode.