I hate to sound contradictory but most folks actually learn on 20 - 25lb beginner bows and go up according to their relative strength in relation to technique. Most adult male competition recurve archers shoot between 30 and 40lb which, combined with the right arrows, is more than enough to shoot the privates from your average gnat if your technique is good.
Longbow and other 'traditional' archers tend to go higher in draw weights and I've yet to figure out exactly why. For a long time I messed around with heavy longbows, mainly to challenge myself and see if I could come up to muster with a heavy Mary Rose warbow. You can't easily hunt with one, and you can't be as accurate or shoot for as long as you could with a 40 - 50lb longbow. Over the last few years I have become more interested in balancing primitive bow/arrow performance and it is surprising just how fast simple equipment can shoot, given the right input.
Learning on a heavier bow is fine but only if you are naturally quite strong - archery uses muscles in a way that you can't emulate and even a big chap is better off learning on a 'jelly' bow. Once good technique has been built up you can increase draw weight within your comfort zone but you need to make sure you stay within it and not go above it. Archery injuries generally last for a very long time and heavy draw weights are one of the main causes of them - heavier weights are also more likely to cause bad form.
I can handle seriously big bows but more often than not I can be found using 45 - 55lb longbows that, because of their design, can shoot faster, flatter and further than your average 80 - 90lb longbow, and because of their lower weight I can shoot them more accurately and for longer periods.
All of my overseas bowhunting is done with a 55lb longbow and I have also successfully hunted with a 45lb longbow - you have to check state regulations for the minimum draw weight permitted though.
This change came from my research into primitive cultures variations on the longbow theme which indicate that many bows were likely to have been in the 40 - 60lb bracket, but if you keep in mind that the thicker strings would have robbed quite a chunk of performance a 60lb primitive bow would probably shoot a lot less efficiently than a modern bow of half that weight.
Maximum output from minimum input, and almost zero chance of injury...
Draw weight is academic next to your ability to put the arrow where you want it to go, and staying well within your personal comfort zone will increase your shooting pleasure (and accuracy)
A lady friend of mine couldn't reach ladies clout range (120 yards) with her well known brand 35lb longbow - I made her one of the same 35lb weight which easily exceeds gents clout distance of 180 yards, with wooden arrows, 3 inch feather fletchings and 100 grain field tips. She had asked for a heavier bow but I made one that I knew she could comfortably handle but that offered far more return for her efforts.
Taking a beginner's course and learning on a jelly bow are a great indicator of where you will end up, not to mention being an essential step depending on the parent archery organisation of the club you are shooting at. Most folks are surprised at how much their shoulders ache after shooting a 20lb beginner's bow for the first time...
Apologies for the thread hijack