I've started cutting back on my red-meat consumption...not for any animal rights or health reasons (I was plenty healthy when I was eating beef)...it was purely for the environmental impact that cattle farming has.
Cattle farming is way WAY worse in terms of environmental impact than chicken & pork. ...and I read a report stating that if we cut our global demand for beef by 40%, that could actually help move us toward sustainable levels. So I cut mine by about 80%, that way I'm doing my part, and someone else's part too lol.
I still don't think veganism is a human's natural state (thus the reason why pure vegans do need to supplement), however, I think overall, our meat consumption is too high. The problem is, it's become too easy to get meat.
Prior to the industrial & agricultural era (and the era of mass factory farming), getting meat meant hard work. You had to know how to hunt, prepare the meat, etc... and there was no guarantee you'd get anything when you went out hunting (aside from maybe some small game or fowl)...so the effort involved with getting meat helped counterbalance and keep things at a sustainable level.
Now, the fattest, laziest, slob who has $4 in his wallet can go to 15 different places within driving distance of his home or work and get some meat. It's not supposed to be that easy lol.