Read the first part of PiHKAL (ie. the part that's deliberately not published on the website the parent HN post links to).
It's all there. He goes in to great detail about exactly how he did what he did and why.
"EXTENSIONS AND COMMENTARY: This specific compound is probably the first sulfur-containing phenethylamine to have been evaluated as a potentially active CNS stimulant or psychedelic. It was a complete, total, absolute unknown. The first trials were made at the sub-microgram level, specifically at 0.25 micrograms, at 11:30 AM on September 3, 1975. Part of this extreme precaution was due to the uniqueness of a new heteroatom in a phenethylamine system. But part was due to the strange manic excitement that occurred at the time of the isolation and characterizing of the final product in the laboratory. Although it was certainly all placebo response, I was jumpy and unable to stay in the lab for more than a few minutes at a time. Maybe dust in the air? Maybe some skin contact with the free base? Now, I know there was nothing, but the possibility of extraordinary potency was real, and I did indeed wash everything down anyway. In fact, it took a total of 18 trials to work the experimental dosage up to as much as a single milligram. In retrospect, overly cautious. But retrospection, as they say, is cheap."
starting at 1/4 microgram (that's 250 nanograms!), took 18 steps up to a milligram. I approve. And thanks BTW.
However, the entry you quote certainly does illustrate his diligence and commitment to safety. I very much doubt he would have been able to discover and sample something like 400+ psychoactive substances in probably many thousands of trials without being as careful and safety-conscious as he was.
Actually, he avoided animal experimentation. In PiKHAL, I believe he wrote that he hadn't experimented with animals in 20 years. His method was to first try each of the substances he discovered on himself.
To paraphrase him he says something like "inserting thermocouples into that rectums of restrained rabbits is not something that I'm much enthused about and I have a jaundiced view of."
I'll try to find that link and update it heh :)
So for your reference that's exactly what I meant by animal experimentation obviously helped him stay safe by giving him some more data on the compound before he took it himself.
edit: link: last paragraph here https://erowid.org/library/books_online/pihkal/pihkal125.sht...
Then again <https://dirtworship.wordpress.com/2013/04/18/sasha-shulgin-o...>
"This (MME) is one of the very few compounds with which I actually risked (and took) the lives of experimental animals" - worth reading the rest