Historically, a human being was not necessarily a natural person in some jurisdictions where a slave was a thing (subject of a property right) rather than a person. In many cases, fundamental human rights are implicitly granted only to natural persons.
Phenylalanine amino acid > Tyrosine amino acid > L-Dopa > Dopamine > Norepinephrine > Epinephrine. Mucuna pruriens is an herb that contains a small percentage of natural L Dopa. Mucuna pruriens is available without a prescription. For more information on mucuna pruriens and levodopa, click on the link provided.
The amino acid tryptophan is found in a variety of foods that include poultry, eggs, fish, dairy, nuts, soy, peanuts and pumpkin and sesame seeds. Further, vitamin B6 is a cofactor for the production of serotonin in the brain, so foods rich in this vitamin may also support higher levels of Melatonin. Many foods naturally include vitamin B6. It is found in a range of animal-based foods, including poultry, fish, beef liver and dairy.