21 We often hear the word “gaslighting,” but what does it mean, exactly?

The expression “gaslighting” comes from the 1938 play Gas Light, which was turned into a film titled Gaslight in 1944. Here, the husband tricks his wife into convincing her that she is mentally unstable to steal from her. The term gaslighting is defined as a kind of manipulation where someone makes a person question his/her reality. As per psychologists, gaslighting is always a serious problem because not believing in your reality always leads to extreme effects. Gaslighting can occur in all kinds of relationships, be it an abusive spouse, manipulative parents, children, coworkers, or scheming bosses. A gaslighting victim does not have a clear grip on the truth and hence ends up making wrong decisions. In cases of gaslighting where the manipulator is someone close, the victim chooses to believe the person, and the gaslighter ends up using this trust to manipulate.

Gaslighting can be deliberate with malicious intent, as well as unintentional. For example, an over-critical parent disapproving of every decision taken by a child may lead the child to believe that he/she is never right. Hence, this may make the child incapable of making correct, independent decisions, thinking it would not be approved by the parent (the gaslighter in this case).

Different ways of gaslighting may include withholding, countering the victim’s version, blocking or diverting the victim’s thinking, trivializing the victim’s feelings, and forgetting or denial by the manipulator. (1, 2)

22 Why do we only get two sets of teeth in our life?

Humans are diphyodont, which means that we grow only two sets of teeth in our lifetime. The first set of 20 teeth is the deciduous set that includes baby teeth, milk teeth, and drop teeth. These support the shape of our jaws while growing and adjust to the size of our faces as they get bigger. As the deciduous teeth fall, the new, permanent, and final set of teeth that we have start to grow. But what about a third set? Can we get more? The answer is most likely no.

This is because our DNA only has instructions for two sets of teeth and not anymore, due to which both the sets grow when they are supposed to and then stop after we successfully grow 32 permanent teeth. For us to evolve and have more than two sets, it is required that we develop challenges that directly affect the survival of our offspring. But that is not happening as we continue to make our foods tender. Often there is not even the need to have a third molar. So, from the evolutionary point of view, we don’t even need a third set, and therefore it is not evolving. (1, 2)

23 Do oxygen levels drop a lot in winter when trees shed their leaves?

The short answer is yes. Oxygen levels do drop, and carbon dioxide levels increase during winter in the Northern Hemisphere when most trees shed their leaves. But this drop is insignificant, which means no matter what, the quantity of oxygen in our atmosphere is fairly steady at any time of year. By volume, 21% of the air we breathe is O₂, and almost all of this oxygen comes from photosynthesis.

But it is not just the trees that produce oxygen. About half or more of the oxygen in our atmosphere comes from the oceans by microscopic algae-like creatures called “phytoplankton.” Marine cyanobacteria called Prochlorococcus could be the richest producer of photosynthesis on Earth. Scientists have found that O₂ levels decrease by about 24 parts per million by volume during winter in the Northern Hemisphere. Our atmosphere is around 210,000 parts per million of oxygen, which subsequently means that this decrease is only about 0.01%. So, there is no need to worry yet. Even though there is slightly less oxygen, there is still plenty around for you to breathe easily. (1, 2)

24 Why are our faces more prone to blackheads and pimples than the rest of our bodies?

The frequency of our blackheads and pimples depends on the sensitivity of the sebaceous glands. The sebaceous glands are tiny glands found near the surface of our skins, attached to hair follicles. These glands produce sebum which is an oily substance that moisturizes and protects the skin. Acne, or pimples, is the result of too much sebum. When our glands overproduce sebum, it clogs our pores and causes the growth of the bacteria C. acnes. This, in turn, generates the inflammation in our skin that forms acne, blackheads, whiteheads, pimples, etc.

So why, mostly on our faces? In humans, though sebaceous glands occur all over the body, they are present in the highest numbers, particularly on the face and scalp. Our faces, in particular, may have as many as 900 sebaceous glands per square centimeter of skin. Therefore, it makes sense that our faces would be more prone to pimples, blackheads, acne, etc., than the rest of our bodies. (source)

25 Why do wine bottles have a large indent in the base?

All wine bottles have a conical-shaped indent at the bottom. This is called a “punt.” Back in the days when all bottles were handmade, the indent was given to push up the seam and guarantee the bottle could stand upright and check that there wasn’t a sharp point of glass on the bottom. The punt also added to the structural strength of the wine bottles. Today, bottles are much stronger and machine-made, but punts are still added in keeping with the tradition.

Wine enthusiasts and researchers have also discovered other purposes for having this punt. It makes the task of pouring a glass of wine with one hand easier while resting one’s thumb in the indent of the bottle. The indent at the bottom is also known to collect sediment as the wine ages inside the bottle. But the indent has no impact whatsoever on the quality of the wine. At best, it can deceive buyers into thinking that the bigger bottle has more wine, when in fact, it can just be the opposite. (source)