Steam wasn't the energy source, it was the working fluid. The energy source was coal, or later oil. Railroad companies recognized the utility of overhead electrification pretty much as soon as the technology was available, since you didn't need to carry around an entire steam engine and coal car, though nobody wanted to be the first to electrify their system. Diesel seemed like it would be a temporary stopgap in the transition to overhead electrification, but since it didn't need expensive railside infrastructure it basically became the default by the late 50s.

Earthquakes, and tectonic activity in general, redistribute mass in the Earth's crust. This doesn't affect the Earth's orbit but it does effect the Earth's rotation (https://youtu.be/M6PuutIm5h4). The change is small enough to be irrelevant in day-to-day life, even if it is ultimately changing the length of a day.

Hunter gathers probably spent a few hours a day hunting and/or gathering and the rest of their time sitting around a fire, processing their food, making and repairing clothes, telling each other what happened while they were out hunting, teaching kids how to make tools, and playing with dogs. They had to work very hard, and it wasn't idyllic, but it also wasn't constantly stressful. Facing down a charging mammoth or lion is something your stress response is perfectly equipped to handle. Going to your job every day and overworking yourself while you're sick because you can't afford to take time off and worrying about whether your paycheck will cover this month's rent and what you'll have to do if it doesn't is from an evolutionary perspective an outside context problem.

Whether there's carbon in it

A lot of languages have "romanization" schemes- ways to write the language using Roman or English letters. Chinese uses Pinyin, Japanese uses Hepburn, Arabic uses a collection of formal and informal ones, and so on. These tend to be somewhat systematized so there's a degree of standardization.

Blind people naturally smile and deaf people know how to laugh, so it's most likely that these are inherent behaviors, not learned.

Football is a game that emerged in medieval England. They called it football because you played it on foot, not horseback. Medieval football is vaguely similar to the sports it shares a name with today: two teams fight to control a ball and bring it to the goal on their end of the field. In those days you could carry the ball with your hands, and the field was usually the main street in your town or village. There were tons of regional variations, and over time these variations took on their own characteristics.The town of Rugby had a set of rules people there liked, so those eventually standardized into what we call Rugby. When football came to the US it developed into Gridiron football, or American football. Back in England, the sport was standardized into more or less its modern form, and in the proccess it picked up a nickname: Soccer, from a slang convention applied to "Association football". As I understand it, this nickname wasn't very popular in England- it had a class character, and it was seen as posh, appropriative, and alienating to working class fans and players, who preferred its old name of football. Soccer is the word that caught on when the sport was introduced to the US, because we already had a sport called football. A popular urban legend is that English football fans stopped using the word soccer because it's the word American fans were using, but it's more about that class dimension I mentioned earlier.

Or they only got created when weather permitted. It parts of Germany it was illegal to make beer during the winter because low temperatures make the ferment inconsistent and unpredictable. You had to make all your beer ahead of time and store it. Candy is similar- high humidity interferes with evaporation of water from the sugar, making it sticky. Many people don't make candy before or after heavy rain or storms.

Plus stuff like sneezing, coughing, and diarrhea are useful for getting new bacteria and viruses out of the body and into another host. So germs that cause those kinds of reactions have a selective advantage.

It's not so much the container it's kept in as the conditions it's kept it. Refrigerator temperatures slow the growth of bacteria and fungi, and the tight-fitting lid prevents air from oxidizing the food. And preservatives added by the manufacturer are likely to do one or both of those things. Finally, some substances in food have inherent antimicrobial properties, such as the capsaicin that makes the chilis spicy.

My neighbors have friends with chickens and every few weeks they give me a few cartons of green eggs

It does kill germs, but it's not abrasive enough to lift off plaque. A long time ago toothpaste used to be made out of ground-up bricks for tooth-scraping power.