How has the article evolved over time through various amendments?
The article has evolved through various amendments by adding new clauses and modifying existing ones. The most significant changes include:

1. Adding clause (4A) to allow for reservation in matters of promotion, with consequential seniority, for Scheduled Castes and Scheduled Tribes not adequately represented in the services under the State. This amendment was made by the Constitution (Seventy-seventh Amendment) Act, 1995.
2. Modifying clause (4A) to include any class or classes of posts in the services under the State, as opposed to just "any class" as originally stated. This change was made by the Constitution (Eighty-fifth Amendment) Act, 2001.
3. Adding clause (4B) to allow for reservation considerations on unfilled vacancies reserved for being filled up in any succeeding year or years and excluding these from the ceiling of fifty percent reservation on total number of vacancies of that year. This amendment was made by the Constitution (Eighty-first Amendment) Act, 2000.