BP-GA optimization

I downloaded a matlab code about BP-GA optimization from a website. The code doesn't use the ga function in matlab. Instead, there are several functions about crossover, select and mutation. My question is that why don't they use ga function directly? Is it because the code was programmed a long time ago when there was no ga function in matlab at all or because there are some limitations of using ga functions directly?

[José-Luis]

That would be a question better addressed directly to the ones that wrote the code.