How is the US Constitution a living constitution?

The US Constitution is metaphorically referred to be living by some because it is thought by many to have lost its meaning if only interpreted in a strict constructionist originalist manner, which would mean that the Constitution is best interpreted to only hold its strict, very limited meaning that applied to 18th century society. Many of the reasons for this are that rulings such as ones ending racial segregation, bans on interracial marriage, and etc, that are generally accepted and now quite popular very well may not have been stopped were it not for a liberal interpretation of the Constitution. The idea of a "living Constitution" has acceptance among many (though not all) because the concept is accepted to have advanced American society and progressed equal opportunities.

One prime example is the 14th Amendment's so-called 'Equal Protection Clause', which states:

"All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside. No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws."

Originalism would be the philosophy that it should be interpreted to only apply to the historical passage of it - to only apply to freed slaves. Whereas one who prescribes to the philosophy of a 'living Constitution' may take it in a more textualist manner - by what it actually says, "all persons", enabling its interpretation for equal protection on the basis of gender, race (all races, not just freed slaves or African-Americans), disability, or, perhaps - sometimes, sexual orientation.

Some would say that the "Federalist Papers" and the "Anti-Federalist Papers" for the actual conversations and debates that went on surrounding the drafting of our Constitution. However, the relevance would be the judicial philosophy of originalism - the belief that the Constitution should be interpreted as it was written to apply at its adoption, in the 18th century, and not applied to the changes of social mores and perceptions of things like 'equal protection' among the general populace.