Yes, it does

Seriously though, Marijuana doesn't do nearly as much damage to the body as drinking alcohol or smoking tobacco does, though it's never good to set light to
anything and breathe in the smoke as I said.
There's been a lot of argument about cannabis in the UK, with several drug advisors quitting because they are tired of the government using political measures to rate drugs, rather than scientific ones. It should be noted that there
is evidence that smoking pot will affect memory ability in those who start before puberty, though it should be noted, this was through tests being done on mice, but the evidence was pretty convincing, but there have been no long-term damage implied in its effect for people who start smoking it afterwards, the bigger risk is the
method most people use, either a pipe, or mixed with tobacco, which opens you up to the risk of lung-problems, but, at least the pipe method is much lower risk with regards to heart disease.
It should also be noted there are several 'kinds' of Cannabis, things like 'Skunk' are slightly different from the natural breeds, they contain far, far higher quantities of THC, and, as such, have a more profound effect. The real risk is concentration, particularly when on a 'hangover', whilst I don't have a problem with someone smoking it, I do have a problem with someone, for example, attempting to operate heavy machinery whilst stoned.