Although slaves had been sold in the American colonies since at least 1619, slave labor did not come to represent a significant proportion of the labor force in any part of North America until the last quarter of the 17th century. After that time, the numbers of slaves grew exponentially.
A Pharmacologist earns an average salary of $103,686 per year. For the first five to ten years in this position, salary increases sharply, but any additional experience does not have a big effect on pay.
While clinical neuropsychologists earn anywhere from $62,000 to $500,000 a year, the average was closer to $109,800 as of 2005, according to the most recent survey by the American Academy of Clinical Neuropsychology.