The PhD is a doctoral degree, specifically called a "doctor of philosophy" degree. This is misleading because PhD holders are not necessarily philosophers (unless they earned their degree in philosophy!). That said, PhD recipients are able to engage in thought experiments, reason about problems, and solve problems in sophisticated ways.
If a person is interested in applying mathematical techniques and the scientific method to understanding more about the life on this planet, they may be interested in a course within the field of Biological and Life Sciences.
The United States of America is a large country in North America, often referred to as the "USA", the "US", the "United States", "America", or simply "the States". American colleges are funded by "tuition" charged to the student, which is often quite expensive, very commonly reaching into the tens of thousands of dollars per year.
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