If those are yer criteria, they eliminate about 65% of diving candidates.

My experience with kids (including my son) is that they pick up the
skills quickly and master them very well. They also understand the basic
physics and physiology, if presented right, even though they don't have
high school physics.

But yer point about immortality is right on, and they should be
accompanied by an experienced diver until about age 30.

esg

Yepper.  Emotional Maturity would be a major factor IMHO. Mastering the art of
"cool under pressure."  The last thing one needs to do is panic. As I'm sure you know,
underwater, panic can kill you quick, and it can kill you DEAD!

It's one reason why I'm having 2nd thoughts about starting my (soon to be 11 y/o) niece.
I wittnessed an incident where she was having a bad day playing the Wii bowling game,
and as things got worse, she started to get more and more frustrated and keep losing
her concentration ----> Viscious cycle----> Anger---> more frustration ---> more anger
until she decided to take it out on a folding chair (which didn't stay upright or unfolded
for very long). Now, I'm told she "usually gets over it right away" and "regrets her actions"
but at 40+ fsw, it might be too late for regrets.  

She's going to have to master that "anger mgt." thing before I'll take her anywhere near water.

____________________________________________
Regards,

Arnold

PADI Jr Open Water Diver minimum age is 10.    They have to meet all the
same requirements as Open Water Diver plus watch an additional video about
responsibilities and risks with the parent.  Certification dives for 10 & 11
year olds can't exceed 40 ft.  After certification 10 & 11 year olds must
dive with a parent, guardian , or PADI professional and their dives must not
exceed 40 ft.

I wouldn't discount them because of their age.  You really have to evaluate
each kid to see if they can understand the concepts, some can handle it,
some can't.  I certified my daughter at 11 and is still diving with me today
at age 13 and doing great.

Jay

NAUI is age 12 as well, and I don;t see that changing in the future.
I don't do jr diver certs.  My own sons learned to dive, and not from
me, at ages 15 and 16. Once they had finished OW, I did AOW and nitrox
with them both - nitrox once they were 18. And I must say, they are
good divers and great dive buddies.  I didn't want them ever to feel
that either my husband or I were the "parent" in a dive situation - I
wanted them to know that they were a buddy, with equal responsibility
for a dive snce none of us do trust-me dives.

Article from Kelly Hill, below, covering the medical rationale, with
which I am not qualified to either agree or refute.

I can, however, speak from 20 years of dealing with kids aged 13-18 on
a daily basis. Most are not, for various reasons of maturity, physical
size and strength, reasoning ability, and comprehension of risk and
responsibility, ready to dive before age 15-16, about the time you'd
consider trusting them with your car.

MEDICAL ANSWERS, By R. Kelly Hill, Jr., M.D., F.A.C.M., NAUI #9243
"Little kids shouldn't dive. There, I've typed it so that it is very
clear. Just like pregnancy, being a human-in-progress is a
contraindication to diving. There are two rational reasons based upon
diving physiology, and one irrational reason for my position on
[youngsters] diving.
Rational Reason #1: The DCS risk for juveniles is unknown, and there
are no decompression tables or algorithms developed specifically for
them. When experts in diving medicine get together to look at
incidence rates, causal factors and risk analysis, there is little
consensus - and that is for adults not our children. The historical
data collected on the few children who have dived is a very inadequate
sample to determine if children have more or less risk than adults.
Animal experiments have not been particularly helpful in determining
the relative incidence of DCS in this group when compared to adults.
Remember that the basic concept behind the development of
decompression tables is whether or not the test group got bent using
[a particular] schedule. Those groups tend to be relatively small [in
number], until recently were exclusively male, and no one in his right
mind would include children in a test group...
Rational Reason #2: Juveniles have a unique tissue risk for
decompression sickness. Though all of a juvenile's tissues are in
transition, one tissue type in particular is at potential risk for
DCS: bone. As the skeleton grows , it does so by lengthening bones at
their ends, through the growth plates. Just like with other tissues,
if something, such as a bubble, damages this tissue or its blood
supply, the tissue fails. The growth plate has its own set of on and
off-gassing parameters, and they are ones that were not necessarily
included in the testing of decompression schedules. If a growth plate
dies, that bone does not grow from that end and the bone is
permanently distorted. If the distortion is significant, the result
may be surgery, disability or both... the risk is real and the
incidence unknown.
Irrational Reason #1: Risk/Benefit.
Since the data is not clear, why take a risk? Diving is a wonderful
experience, but there are lots of wonderful experiences open to kids,
like growing up with two legs the same length. The benefits of
children diving are not commensurate with the risk.

I think that most of us who dive with our kid(s) figure that we're
watching over them and consider it a solo dive from the aspect of them
being able to ever help us...