Of course computer languages have evolved a lot today but old languages like Fortran, Cobol and others often are used because they operate faster than newer langauges

 The reason for this is there are layers you have to go through every time you write a new language, often it is going to be interpreted or "translated"  by a previous or "Grandfather" or "Father" or ancestor language in order to work. 

One way to look at this is like doing math and then you are doing higher and higher math as you create Computer languages with one language often built upon the other.

All computers use machine language which is zeros and ones basically. As you move above machine language there are all sorts of things that start slowing processing down. However, as processors process faster and faster over time this became much less of a problem in having so many layers (and languages being translated from one language to another up the chain. But, for the speediest still of things you are trying to do languages like Fortran and COBOL always will tend to process faster than newer languages for the reasons I outlined above.

For example, one of the more recent languages is HTML used for the Internet. Then Java was created as well as other compatible languages built in a way on top of HTML. So, this is just one example of how one language is the basis and then other languages are built "on top of" that original computer language that was created for some purpose.