Found those two from a quick search. I know there are other research on this topic out there, just can't remember how I found them.

https://link.springer.com/referenceworkentry/10.1007/978-3-319-16999-6_2352-1

https://scholar.google.com/scholar?start=10&q=life+expectancy+hunter+gatherer&hl=fr&as_sdt=0,5#d=gs_qabs&t=1679844806366&u=%23p%3DMLcekP_DW7QJ

They did! Atleast in some population, but not to the same extend as we do. There were teeths that had sign of abrasion that were not due to food or foreign particle, but most likely from tooth pick. There are even dental procedure that were perform to remove cavities. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4504065/

Makeshift tooth brush from twig are used in a variety of place and, while there are not evidence, it would not be surprising if people in the past did use those.

At last, people were less prone to dental cavities, maybe 3% to 15% of teeths had cavities. Their overall dental health was just much better than ours.

MdmA is far from a miracle drug, but it does allow some one to open up more and talk about themself. It also ease the bond between people. Since therapy need to start with a bond of trust between the patient and the professional, it accelerate the treatment.

Ketamine is very fascinating, from what I remember, because the effect last longer than the drug. It allow some new neural connection, which help to change how one perceived the world. Ketamine in itself is not the solution, but it make it easier to help some one to get out of depression, since it is easier to change the way you perceived the world.

It definitly would and they might be doing it, but it is a very long process since it involve multiple breed. They would need to find out how to make children of the children resistant. They never breed the chickens they sell. They mix a+b= c than c+b= d where d is the final breed, but they always restart at c+b, never breed d with d or the result would be different.

I knew a guy which did that with bees for varroas and he lost over 90% of his bees. It took him years to come back, but his hives now deal better agaist the varroa, but he is a crazy one.

Unless you are talking about breeder, most farmers buy eggs which are breed specifically for what they want (eggs or meat). Most commercial breed are three breed cross, mother and father different, breed this chicken again to get what you want. They use very specific breed to obtain the result they seek. They would need to do this with the parents for many generations to get a stable breed again. Not that easy to do and they might not have the sae exact traits they want.

Detergent can rip off the oil, but the hot water and the tumbling actually change the structure over time. This will transform your wool into felt. Felt is made by applying pressure and hot water. When you make your own wool, you seperate two different length of fiber. The long one are spun and the short one are use to make felt.

I think he over simplified what he was doing, but it was most likely some sort of fungicide or bactericide. The only case I know where it is commonly use is for ash dieback, a fungus transmitted by the emerald ash borer. It's a good way to make sure it is transmitted through all the tree's system.