What are the ways to do the dishes without dish soap?

In washing dishes it is hot water that removes all bacteria's. If you have greasy dishes you need soap to absorb the grease. You can use straight baking soda or powder as an abrasive to remove grease, or salt. Get a basin to place in your sink add water and some vinegar. Once you rinse your dishes after washing, dip them in basin and then rinse with hot water again. BOOM YOUR DISHES ARE SOOOOO CLEAN.

We are just conditioned to think we need dish soap.

Old west and camping way to clean a cast iron skillet or pot was to scrub it with sand and put it bqck on the embers of the fire.

But of course soap and water will limit diseases.... you can get hepatitis from usinga utensil or glass from someone who has it (it's not just a disease junkies get from sharing needles)

How would humans fare in a prehistoric world where all animals had human-level intelligence?

In a pre historic world? We would probably go extinct in a few decades. Just imagine dinosaurs with the brains of humans. They design traps , weapons and stuff to hunt us down. The only advantage humans have over other animals is an extremely advanced brain.

What would happen if suddenly everyone's right arm disappeared?

Having broken my right, and dominant, arm two months ago, I can offer up the following:The sheer mechanics of living will take much longer. Showering, getting dressed, feeding yourself are big tasks in their own right.There will be many more

Can we buy pets online?

Yes,there are some websites from which you can buy pets online but they only deliver in certain places. Though I'd suggest you not to buy any animal online. As Ram Keswani has said, if you want to to get a dog or a cat,instead of buying one,just adopt one. It doesn't really matter whether the dog you