If you read the entire article, which I suspect many commentators haven't bothered to do, you'll find that there are so many confounders in the data that any trend is highly suspect. For example, this one is a bit amusing:
> "After ejaculation, sperm count decreases and takes a while to build back up again; if your community’s ejaculation frequency is changing (eg people have gained access to online porn), that will change its average sperm count."
If one wanted to, one could claim that the sexually frustrated society of the 1950s was resulted in the high sperm count samples from that era, and that sexual liberation movements of the 1960s and 1970s resulted in people having sex more frequently, hence the lower sperm counts in submitted samples.
Of course, there are about a half-dozen other confounders one could cherry-pick so that's not a valid conclusion either. All in all the trend doesn't seem to be very well-supported, compared to other studied trends like the increase of CO2 in the atmosphere due to fossil fuel combustion, the decrease of oxygen in the deep ocean due to warming and fertilizer inputs, an increase in heavy metals in the environment due to centuries of coal combustion, etc.
Were men sexually frustrated in the 50s? I don't know the stats, but I do know that a lot of the nostalgia about that period comes from high rates of stable marriage and a male-lead household.
At least on paper, it sounds like every man basically had an unlimited sex license.
I read that as there being much more social pressure against infidelity in the 50s as compared to the 60s/70s.
Stable marriage certainly doesn't translate into unlimited sexual license. What's the old saying? A newly-married couple puts a marble in a jar every time they have sex during their first year of marriage. Then remove one marble every time, beginning year 2 and beyond. They never empty the jar.
>What's the old saying? A newly-married couple puts a marble in a jar every time they have sex during their first year of marriage. Then remove one marble every time, beginning year 2 and beyond. They never empty the jar.
That certainly doesn't line up with my experience, or the stats I've read.
From what I've heard, it's pretty common for married couples to keep at it (with a slow decline, as both parties age) until they physically can't any more. And with modern technology (cialis etc.), that age keeps getting pushed further and further up.
I agree here. The graphs showing the trend lines in the bubble graph read to me as pretty much noise.
I looked at the paper Scott pulled it from and couldn't find the r2 value.
Perhaps someone with a better stats knowledge can help me out here in trying to interpret how the 95% CIs that are presented help relate to something like an r2 value? Is the data presented three dimensional? What's going on here?
The authors of the paper state: "These findings strongly suggest a significant decline in male reproductive health, which has serious implications beyond fertility concerns". But because of my limited stats knowledge, I'm seeing the opposite of their conclusion.
Are there studies that taken MTBE into account (eg asking men to build of x days of material before collection, or at least only comparing men across time with similar MTBEs)?
> "After ejaculation, sperm count decreases and takes a while to build back up again; if your community’s ejaculation frequency is changing (eg people have gained access to online porn), that will change its average sperm count."
If one wanted to, one could claim that the sexually frustrated society of the 1950s was resulted in the high sperm count samples from that era, and that sexual liberation movements of the 1960s and 1970s resulted in people having sex more frequently, hence the lower sperm counts in submitted samples.
Of course, there are about a half-dozen other confounders one could cherry-pick so that's not a valid conclusion either. All in all the trend doesn't seem to be very well-supported, compared to other studied trends like the increase of CO2 in the atmosphere due to fossil fuel combustion, the decrease of oxygen in the deep ocean due to warming and fertilizer inputs, an increase in heavy metals in the environment due to centuries of coal combustion, etc.