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Why modern men are losing their testosterone

Research has shown that men today have less testosterone than they used to. What's happening?

Flickr user Tom Simpson
  • Several studies have confirmed that testosterone counts in men are lower than what they used to be just a few decades ago.
  • While most men still have perfectly healthy testosterone levels, its reduction puts men at risk for many negative health outcomes.
  • The cause of this drop in testosterone isn't entirely clear, but evidence suggests that it is a multifaceted result of modern, industrialized life.

Remember Frank Sinatra's swagger, John Wayne's quiet confidence, and Burt Reynold's impressive mustache? They were icons of masculinity for a lot of people, and many folks today point to those icons when bemoaning a perceived loss of masculinity in our society.

Well, Frank Sinatra had a violent temper, John Wayne was a racist, Burt Reynolds was a womanizer, and they all drank way too much. Our values have changed more than the storied qualities of "manliness." Despite this, there is something to the argument that men used to be more manly back in the day.

A study on a large sample of American men found that the average testosterone level has been dropping by as much as 1 percent per year. Testosterone levels lower naturally with age, but this study found that a 65-year-old man in 1987 had about 17 percent more testosterone than a 65- year-old man in 2004. This wasn't just limited to Americans either; a Danish study found similar results. Anecdotally, sex counselor Ian Kerner told CNN that he's noticed "an increasing number of young guys are complaining of sexual concerns, such as diminished libido and erectile problems, more commonly seen in older men."

How bad is this?

It's not a disaster. Most men today still have perfectly healthy levels of testosterone even if it is dropping year to year. But if testosterone levels get too low, then we start to see a slew of bad effects.

Testosterone promotes attention, memory, spatial reasoning, and energy — essentially, it makes you sharper — and, of course, it increases libido and muscle mass. When Testosterone counts get too low, men can begin to feel fatigued, lose sexual interest, gain weight, and lose muscle mass. In addition, there is a link between low testosterone levels and depression.

There's also a wide association between low testosterone levels and disease. One study, published in the spring, found that people with a testosterone deficiency (defined as less than 300 nanograms of testosterone per deciliter) were at greater risk for obesity, cardiovascular disease, hypertension, diabetes, and other diseases. It's important to note that this is correlational data; it's very difficult to definitively prove that low testosterone causes these negative outcomes. But the odds are that doing the activities that keep your testosterone levels up will also help prevent these very undesirable conditions.

As testosterone levels decrease with age or in response to medical conditions, some people choose to receive testosterone therapy and inject what their body fails to produce.

Flickr user Linden Tea

What's the cause?

Unfortunately, the reason why testosterone counts keep dropping over the years isn't clear, but there are some likely candidates. One surprising possibility is that people smoke fewer cigarettes now. Even though everything else it does is terrible for you, smoking actually raises testosterone levels. And back in Frank Sinatra's day, smoking was the norm, not the exception. But please, don't light up to make yourself manlier. It's a bad idea.

Our rising rates of obesity, too, are probably contributing. Between 1999 and 2016, obesity in American adults increased by nearly 10 percent. Obesity and testosterone create something of a vicious cycle: obese men tend to have lower testosterone , and men with lower testosterone tend to become obese. This happens because fat cells metabolize testosterone and convert it into estrogen. In addition, obese people have lower levels of SHBG (sex hormone binding globulin), which transports sex hormones like testosterone through the blood.

However, the most likely candidate is pollution. Research has shown that chemicals that are commonly found in medicine and pesticides inhibit testosterone. These chemicals are seeping into our water, contributing to fertility problems in fish. The researchers also speculate that this same mechanism is occurring in humans as well.

In addition, research on Native American tribes found that higher levels of polychlorinated biphenyls (PCBs; a component in industrial coolants, as a plasticizer, and in many other applications) in the males' systems was associated with lower testosterone counts. We've known that PCBs are toxic for years, but the chemical lasts for a very long time. Other chemicals, like bisphenol A (BPA; a plastic) and triclosan (an antibacterial agent) have been shown to disrupt the human hormone system, either by mimicking estrogen or blocking the activity of testosterone. Once chemicals such as these get into the environment and enter the food chain, they are very difficult to remove.

Industrial pollutants have a myriad of negative effects on our health, one of which can is the blocking of testosterone in the body.

(Photo by ROMEO GACAD/AFP/Getty Images)

What can be done?

Good news: The things that are lowering men's testosterone levels may be complicated, but combating this issue is simple and probably what you would have guessed anyways. Eat a healthy diet, exercise more, and get a good night's sleep. If you really want to go the extra mile, avoid eating or drinking from plastic containers. Finally, get political: When environmental regulation goes out the window, so too does your health. Contrary to the stereotype, becoming a treehugger might be the best way to save your masculinity.

Hulu's original movie "Palm Springs" is the comedy we needed this summer

Andy Samberg and Cristin Milioti get stuck in an infinite wedding time loop.

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  • Two wedding guests discover they're trapped in an infinite time loop, waking up in Palm Springs over and over and over.
  • As the reality of their situation sets in, Nyles and Sarah decide to enjoy the repetitive awakenings.
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Our ‘little brain’ turns out to be pretty big

The multifaceted cerebellum is large — it's just tightly folded.

Image source: Sereno, et al
Mind & Brain
  • A powerful MRI combined with modeling software results in a totally new view of the human cerebellum.
  • The so-called 'little brain' is nearly 80% the size of the cerebral cortex when it's unfolded.
  • This part of the brain is associated with a lot of things, and a new virtual map is suitably chaotic and complex.

Just under our brain's cortex and close to our brain stem sits the cerebellum, also known as the "little brain." It's an organ many animals have, and we're still learning what it does in humans. It's long been thought to be involved in sensory input and motor control, but recent studies suggests it also plays a role in a lot of other things, including emotion, thought, and pain. After all, about half of the brain's neurons reside there. But it's so small. Except it's not, according to a new study from San Diego State University (SDSU) published in PNAS (Proceedings of the National Academy of Sciences).

A neural crêpe

A new imaging study led by psychology professor and cognitive neuroscientist Martin Sereno of the SDSU MRI Imaging Center reveals that the cerebellum is actually an intricately folded organ that has a surface area equal in size to 78 percent of the cerebral cortex. Sereno, a pioneer in MRI brain imaging, collaborated with other experts from the U.K., Canada, and the Netherlands.

So what does it look like? Unfolded, the cerebellum is reminiscent of a crêpe, according to Sereno, about four inches wide and three feet long.

The team didn't physically unfold a cerebellum in their research. Instead, they worked with brain scans from a 9.4 Tesla MRI machine, and virtually unfolded and mapped the organ. Custom software was developed for the project, based on the open-source FreeSurfer app developed by Sereno and others. Their model allowed the scientists to unpack the virtual cerebellum down to each individual fold, or "folia."

Study's cross-sections of a folded cerebellum

Image source: Sereno, et al.

A complicated map

Sereno tells SDSU NewsCenter that "Until now we only had crude models of what it looked like. We now have a complete map or surface representation of the cerebellum, much like cities, counties, and states."

That map is a bit surprising, too, in that regions associated with different functions are scattered across the organ in peculiar ways, unlike the cortex where it's all pretty orderly. "You get a little chunk of the lip, next to a chunk of the shoulder or face, like jumbled puzzle pieces," says Sereno. This may have to do with the fact that when the cerebellum is folded, its elements line up differently than they do when the organ is unfolded.

It seems the folded structure of the cerebellum is a configuration that facilitates access to information coming from places all over the body. Sereno says, "Now that we have the first high resolution base map of the human cerebellum, there are many possibilities for researchers to start filling in what is certain to be a complex quilt of inputs, from many different parts of the cerebral cortex in more detail than ever before."

This makes sense if the cerebellum is involved in highly complex, advanced cognitive functions, such as handling language or performing abstract reasoning as scientists suspect. "When you think of the cognition required to write a scientific paper or explain a concept," says Sereno, "you have to pull in information from many different sources. And that's just how the cerebellum is set up."

Bigger and bigger

The study also suggests that the large size of their virtual human cerebellum is likely to be related to the sheer number of tasks with which the organ is involved in the complex human brain. The macaque cerebellum that the team analyzed, for example, amounts to just 30 percent the size of the animal's cortex.

"The fact that [the cerebellum] has such a large surface area speaks to the evolution of distinctively human behaviors and cognition," says Sereno. "It has expanded so much that the folding patterns are very complex."

As the study says, "Rather than coordinating sensory signals to execute expert physical movements, parts of the cerebellum may have been extended in humans to help coordinate fictive 'conceptual movements,' such as rapidly mentally rearranging a movement plan — or, in the fullness of time, perhaps even a mathematical equation."

Sereno concludes, "The 'little brain' is quite the jack of all trades. Mapping the cerebellum will be an interesting new frontier for the next decade."

Economists show how welfare programs can turn a "profit"

What happens if we consider welfare programs as investments?

A homeless man faces Wall Street

Spencer Platt/Getty Images
Politics & Current Affairs
  • A recently published study suggests that some welfare programs more than pay for themselves.
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