A query regarding historical progression and/or resources allotted

[SaadKaleem]

Firstly, I'd like to congratulate Twitter for making this huge step of transparency and which I believe is certainly a step in the right direction.

I'd just like to ask, what has been the historical progression regarding the recommendation system, in particular:

• How many contributors (and/or hours) in your estimate have been part of this project?
• Was this algorithm developed as part of the original version of Twitter?

FYI: I'm asking this just for my curiosity, and this is certainly a genuine question.