It’s no secret that sperm counts have been dropping like rocks over the past 70 years or so (though the trend may have recently leveled out.)
” Sperm counts in the 1940s were typically well above 100m sperm cells per millilitre, but Professor Skakkebaek found they have dropped to an average of about 60m per ml. Other studies found that between 15 and 20 per cent of young men now find themselves with sperm counts of less than 20m per ml, which is technically defined as abnormal.” — from The Independent, “Out for the count: Why levels of sperm in men are falling“
While environmental effects (like smoking,) have effects on sperm counts in adults, these appear to be basically small or short-lasting. The biggest, longest-lasting effects on sperm counts appears to be the unterine environment where the future-low-sperm-count-male’s testicles were developing. Improper fetal testicle development => low sperm count for life. Eg,
“A man who smokes typically reduces his sperm count by a modest 15 per cent or so, which is probably reversible if he quits. However, a man whose mother smoked during pregnancy has a fairly dramatic decrease in sperm counts of up to 40 per cent – which also tends to be irreversible.”
What elsecould make a uterine environment hostile to testicular development?
How about too much estrogen?
I’ve posted before about Diethylstilbestrol, (or DES,) is a synthetic nonsteroidal estrogen. Between 1940 and 1971, DES was given in large quantities to pregnant women to prevent miscarriages. Unfortunately, it turns out that pumping babies full of unnaturally high levels of estrogen might be bad for them–DES was discontinued as a medication for pregnant women because it gave their daughters cancer, (an actual epigenetic effect) and the sons appear to have high rates of transgender, transexual and intersex conditions.
Quoting the Wikipedia:
“In the 1970s and early 1980s, studies published on prenatally DES-exposed males investigated increased risk of testicular cancer, infertility and urogenital abnormalities in development, such as cryptorchidism and hypospadias.
“… The American Association of Clinical Endocrinologists (AACE) has documented that prenatal DES exposure in males is positively linked to a condition known as hypogonadism (low testosterone levels) that may require treatment with testosterone replacement therapy.
“… Research on DES sons has explored the long-standing question of whether prenatal exposure to DES in males may include sexual and gender-related behavioral effects and also intersex conditions. Dr. Scott Kerlin, a major DES researcher and founder of the DES Sons International Research Network in 1999, has documented for the past 16 years a high prevalence of individuals with confirmed prenatal DES exposure who self-identify as male-to-female transsexual, transgender, or have intersex conditions, and many individuals who report a history of experiencing difficulties with gender dysphoria.
“… Various neurological changes occur after prenatal exposure of embryonic males to DES and other estrogenic endocrine disrupters. Animals that exhibited these structural neurological changes were also shown to demonstrate various gender-related behavioral changes (so-called “feminization of males”). Several published studies in the medical literature on psychoneuroendocrinology have examined the hypothesis that prenatal exposure to estrogens (including DES) may cause significant developmental impact on sexual differentiation of the brain, and on subsequent behavioral and gender identity development in exposed males and females.”
Here is an excerpt from a paper, published in, I think, the early 40s.
Since the image quality is low, I’ve done my best to type it up for you:
“Experimental Intersexuality: The Effects of Combined Estrogens and Androgens on the Emryonic Sexual Development of the Rat
“RR. Greene, M. W. Rurrill and A. C. Ivy
“Department of Physiology and Pharmacology, Northwestern University Medical School, Chicago, Illinois
“In previous publications the authors have reported and described in detail the effects of large doses of sex hormones on the embryonic sexual development of the rat. Androgens, when administered to the pregnant female, cause a masculinization of the female embryos (Greene, Burrill and Ivy, ’38, ’39 a). The female type of differentiation of most sexual structures is inhibited and a male type of differentiation of those structures is stimulated. Administered estrogens cause a femininization of the male embryos (Greene, Burrill and Ivy, ’38, ’40) in that they inhibit the masculine type of differentiation of some sexual structures and, instead, cause a female type of differentiation.
“…The experimental demonstration that estrogens do have a profound effect…”
What are external sources of estrogens in modern life?
Birth control pills. I know FTM trans folks birth control pills for the hormones in them. (They are often cheaper and easier to get than hormones specifically prescribed for trans folks, especially if you have a female friend.)
Can those hormones stick around in a mother’s body even after she discontinues taking the pills?
Fat and estrogen appear to be correlated:
“Other conditions that cause low estrogen levels in younger women include excessive exercise, eating disorders and too little body fat.” (source)
“Excess estrogen in the body causes weight gain around the abdomen and upper thighs. … Weight gain caused by estrogen starts a vicious cycle. Excessive body fat produces the aromatase enzyme that synthesizes estrogen, thus creating more estrogen in the body, which then promotes additional weight gain, and so on, says Hofmekler.” (source)
“Researchers have found a correlation between estrogen and weight, particularly during menopause, when estrogen levels drop, but weight tends to rise. But since fat cells can produce estrogen, the issue facing researchers is how to target the estrogen receptors that will boost energy and manage hunger and not contribute to menopause-related weight gain.” (source)
“For postmenopausal women, estrogen levels increase with increasing BMI, presumably because conversion of androgens to estrogen in adipose tissue is a primary source of estrogen…” (source)
Since Americans have been getting fatter over the past century, I’d expect estrogen levels to be up, but I’ve found no studies on the subject so far. (Also, the Wikipedia claims there’s no evidence that birth control pills make people fat.)
However, I have found quite a bit of evidence that giving synthetic estrogen to animals makes them fatter:
(Stilbosol is another name for DES, as you may note in the ad’s upper right hand corner.)
Since the picture quality is bad, I’ll try to type it up for you:
“Ralph has been feeding cattle in New York state for 20 years. He runs 300 head a year through his feed lot, buying mountain (?) calves at 400 pounds and finishing them to about 1,000 pounds. …
“”I lean very heavily on college tests and they’re in favor of Stilbosol. The first time we tried it, back in 1955, I noticed a very definite improvement in appetite.
“”Stilbosol is a ‘must’ in our feeding operations. It has added to our profit. If it didn’t, we wouldn’t be using it.””
“We bring our cattle into the lots around 600 pounds. Feed for about 150 days. … We feed to all weights (950 to 1150 pounds) and take a little chance from time to time and feed t heavier weights,” Dan stated.
“We get about 2.75 lbs. daily gain. And I figure Stilbosol accounts for (unreadable) to 1/2 lb. of that daily gain. …
“Does Stilbosol make us money? There’s no doubt about it! Stilbosol has revolutionized the cattle business. I guess it’s the only good break through in the last ten years.”
“”I tested Stilbosol. Took a bunch of 315 Montana yearlings and split them up. One group was actually lighter than the other. The only change I made in their rations was the addition of Stilbosol. The lighter group received Stilbosol. I figured that the lot fed Stilbosol gained over 1 1/2 lb. per day more than the lot which had no Stilbosol.
“”With all the competition, a man can’t afford to pas up anything that will lower his cost of grain. Stilbosol is one of them.””
“We were trying to find the cheapest, most efficient ration. One group of calves received a ration containing Stilbosol. Another received a similar ration without Stilbosol. The group receiving Stilbosol had a feed conversion of (I can’t tell the number, but it’s clearly a single digit followed by .4). The group receiving no Stilbosol had a feed conversion of 10.35. The Stilbosol group gained 2.49 pounds per day. The group that did not receive Stilbosol gained 2.13 pounds per day.
“With Stilbosol, we figure our cost of grain to be substantially lower than similar rations without Stilbosol.) “
Four farmers wouldn’t lie to us, would they?
Interestingly, eating large quantities of beef while pregnant was one of the things that The Independent article (linked at the top) noted was correlated with low sperm counts years down the road in the all-grown-up-fetuses.
Of course, people who eat more beef may just weigh more, or have some other factors besides adulterations in the cattle feed.
DES was also put in chicken feed, for the exact same reasons as cattle feed, until it came out that DES causes cancer in humans. It was discontinued as a feed additive in the late 70s.
These days, I don’t know what–if anything–they’re using to finish cattle, but we may note that the vast majority of cattle are still finished in feedlots where they get much fatter than they would naturally. (That is, by wandering around eating grass like they normally do.) Feedlot cattle are, to put it bluntly, unnaturally fat.
Now I’m going to do a little math. The Independent article was published in 2010, and states that the article on falling sperm rates was published 19 years prior, or in 1991. The study therefore compared men in the 1940s to men in the 1980s and 1990. Men in the 1940s were fetuses before the age of feedlots, birth control pills, DES, or DES-fed cattle and chicken. Young(ish) men in 1990, by contrast, were born between 1950 and 1970–all within the era of feedlots, BCPs, DES, and DES-fed cattle and chicken.
If it is true that sperm counts have stabilized since the 90s, that is a point potentially in favor of my theory, since after the 70s, DES was basically gone.
This is all me speculating out loud, of course.