Well, if you can't trust Wikipedia who can you trust? (wry grin)
"The JMT is traditionally hiked north to south, from Yosemite Valley to Mt. Whitney. There are advantages to starting in Yosemite Valley and hiking south. Although there is a significant net altitude gain this way, starting at a lower altitude allows the hiker time to acclimate to the elevations of the trail rather than immediately having to tackle a 6,000-foot (1,800 m) climb to the summit of Mt. Whitney. In addition, there are several resupply points convenient to the JMT during its northern half (Tuolumne Meadows, Reds Meadow, Vermillion Valley Ranch, Muir Trail Ranch), allowing the hiker to carry a lighter food load early in the hike and also to exit the trail easily if problems arise. The southern half of the JMT is more remote and generally higher in elevation, thus making it more appropriate for the second half of the hike when maximum conditioning has been attained."
That all seems quite reasonable, and in line with what I've read in contemporary guide books and on the web. Also the OG Starr's Guide to the JMT/High Sierra implies a Yosemite start (at least from what my quick skim revealed). And, importantly, if I CANNOT trust the group-wiki'ed Wikipedia entry above, then how in the world can trust it's very next paragraph to be true, and not some figment of web vapor? (larger grin)
"The speed record for fastpacking the John Muir Trail without resupply (as of 2007) is held by Michael Popov, who completed the trail in 4 days, 5 hours, and 25 minutes. Popov carried all of his equipment and received no outside assistance."
I read it on the internet. It must be true.
(Also, great pictures!)