The microbiome is the collection of microorganisms in an environment and plays an important role in human health. An imbalance of 'good' microbes compared to 'bad' is linked to adverse health outcomes. A person's gut microbiome with a higher number of different bacterial species is considered a marker of gut health but no one is really sure what that means.

This is something puzzles and scares some people. Why is most of the Amazon jungle still untouched by fire? Isn't there a risk that the Brazilian wildfires sweep across the entire Amazon and destroy all the remaining tropical forest? However, we get wildfires in Brazil every year, and this hasn’t happened before. In 2005 for instance there were many more fires than today, yet only a small part of the Amazon burnt. So why is that?

I will also cover some other things that scare people, for instance many are scared we will run out of oxygen - no - this can't happen even if we burnt all the biomass on Earth, or even if all plant life magically stopped producing oxygen for thousands of years. Or they worry about the effect on the Paris agreement:

If marijuana has analgesic properties, people will try it to potentially manage their pain, but it is unclear if it does or not. Fortunately, the U.S. Drug Enforcement Administration signaled it is expanding its marijuana research program will draft guidelines for producing the drug for scientific and medical research. 

Until there are science answers it is people trying all of the above, and that creates confounders for other kinds of research. A new study says adults who take prescription opioids for severe pain are more likely to have increased anxiety, depression and substance abuse issues if they also use marijuana. But did marijuana cause the depression or is it being used to mitigate it? 

The ketogenic diet is a high fat, low carbohydrate diet that has become a health fad but it was originally posited as a benefit for people with epilepsy.
Some mosquito species, such as Aedes aegypti, have been able to weave their way through evolutionary time despite having no ecological value, basically being just delivery mechanisms for things like Dengue fever, the most common vector-borne disease in the world.

We could wipe them out and the rest of the ecosystem would be just fine but environmentalists have promoted a lot of fear about science-based mitigation approaches, like a male mosquito rendered sterile, and they hate pesticides more than they love poor people, so that leaves...clothes?
China bans some chemicals whether or not the evidence shows it, and the United States should be more like communist dictatorships, suggests a Center for Biological Diversity blogger in a press release for their latest op-ed in Environmental Health.
Exercise is obviously physically beneficial and there are claims it also releases happiness-inducing hormones - and it may work that way for a few but if you are suffering from depression the last thing you need is someone in a Live Love Laugh shirt asking if you tried going for a walk.

Fires in the Amazon rainforest have captured attention worldwide in recent days. Brazilian President Jair Bolsonaro, who took office in 2019, pledged in his campaign to reduce environmental protection and increase agricultural development in the Amazon, and he appears to have followed through on that promise.

In America, more women than men receive Ph.D.s and at the faculty level are not 2:1 more likely to be offered a job. Not so in France. Only 35 percent of researchers at the French National Centre for Scientific Research are women and the reason may be bias in French culture. 

In France, the concept of science remains much more strongly associated with masculinity than with femininity and it may lead to scientific evaluation committees putting women at a disadvantage during promotion rounds involving men and women researchers, say social science scholars.
If you read the Anglo-Saxon history of England, the island was a backwater savage place populated by sacrificial druids worshiping angry spiritual gods before Rome paved the way for the arrival of modern inhabitants, but that me just be invading victors writing history.

It has been assumed northwestern European trade during the Bronze Age was primarily socially embedded, as in the exchange of gifts.  It turns out people in England, before the invasions by Celts, Picts, Irish, Angles, Saxons, Romans, Vikings, and Normans, were using balance weights and scales to measure the value of materials as early as the late second and early first millennia BC