[CCIP]

Originally Posted by Neal Stevens

Still, it puzzles me. Compared to high school football; there were never any women willing or able to match up with men. But in the US Army Rangers, even Navy Seals, there are? Hmm...

I suppose one simple answer to that is that serving in the army is nothing at all like playing football. In fact, there are many qualities that a good football player has which would probably be considered handicaps for a ranger. Good football players (and many other athletes) are almost inevitably huge guys; in many cases, guys who are huge and bulky are at a disadvantage in many military roles (and flat our rejected from others).

The intake requirements for Ranger School, assessed on the first 3 days (of 61) as per wikipedia:

The Ranger Assessment Phase is conducted at Camp Rogers. As of April 2011, it encompasses Days 1–3 of training. Historically, it accounts for 60% of students who fail to graduate Ranger School.[12] Events include:

Ranger Physical Fitness Test (RPFT) requiring the following minimums:
Push-ups: 49 (in 2 minutes, graded strictly for perfect form)
Sit-ups: 59 (in 2 minutes)
Chin-ups: 6 (performed from a dead hang with no lower body movement)
5 mile individual run in 40 minutes or less over a course with gently rolling terrain
Combat Water Survival Test (no longer conducted as of 2010)
Combat Water Survival Assessment, conducted at Victory Pond (previously called the Water Confidence Test). This test consists of three events that test the Ranger student's ability to calmly overcome any fear of heights or water. Students must calmly walk across a log suspended thirty-five feet above the pond, then transition to a rope crawl before plunging into the water. Each student must then jump into the pond and ditch their rifle and load-bearing equipment while submerged. Finally, each student climbs a ladder to the top of a seventy-foot tower and traverses down to the water on a pulley attached to a suspended cable, subsequently plunging into the pond. All of these tasks must be performed calmly without any type of safety harness. If a student fails to negotiate an obstacle (through fear, hesitation or by not completing it correctly) he or she is dropped from the course.
Combination Night/Day land navigation test – This has proven to be one of the more difficult events for students, as sending units fail to teach land navigation using a map and compass. Students are given a predetermined number of MGRS locations and begin testing approximately two hours prior to dawn. Flashlights, with red lens filters, may only be used for map referencing; the use of flashlight to navigate across terrain will result in an immediate dismissal from the school. Later in the course, Ranger students will be expected to conduct, and navigate, patrols at night without violating light discipline. The land navigation test instills this skill early in each student's mind, thus making the task second nature when graded patrolling begins.
A 3-mile terrain run, followed by the Malvesti Field Obstacle Course, featuring the notorious "worm pit": a shallow, muddy, 25-meter obstacle covered by knee-high barbed wire. The obstacle must be negotiated—usually several times—on one's back and belly.
Demolitions training and airborne refresher training.
Modern Army Combatives Program (MACP) training was removed as a part of a new POI at the start of 2009; it was reinstated with Class 06-10. The Combatives Program was spread over all phases and culminated with practical application in Florida Phase. However, MACP has been removed from Ranger again, starting with the Combatives Program in Mountains and Florida and followed by the removal of RAP week combatives in class 06-12.
A 12-mile forced, tactical ruck march with full gear from Camp Rogers to Camp Darby. This is the last test during RAP and is a pass/fail event. If the Ranger student fails to finish the march in under 3 hours, he or she is dropped from the course.

Some of the notes on physical effects of the training:

Physical effects
Following the completion of Ranger School, a student will usually find himself "in the worst shape of his life".[19] Military folk wisdom has it that Ranger School's physical toll is like years of natural aging; high levels of fight-or-flight stress hormones (epinephrine, norepinephrine, cortisol), along with standard sleep deprivation and continual physical strain, inhibit full physical and mental recovery throughout the course.

Common maladies during the course include weight loss, dehydration, trench foot, heatstroke, frostbite, chilblains, fractures, tissue tears (ligaments, tendons, muscles), swollen hands, feet, knees, nerve damage, loss of limb sensitivity, cellulitis, contact dermatitis, cuts, and insect, spider, bee, and wildlife bites.

Because of the physical and psychological effect of low calorie intake over an extended period of time, it is not uncommon for many Ranger School graduates to encounter weight problems as they return to their units and their bodies and minds slowly adjust to routine again. A drastically lowered metabolic rate, combined with a nearly insatiable appetite (the result of food deprivation and the ensuing survivalist mentality) can cause quick weight gain, as the body is already in energy (fat) storing mode.

Food and sleep deprivation
A Ranger student's diet and sleep are strictly controlled by the Ranger Instructors. During time in garrison students are given one to three meals a day, but forced to eat extremely quickly and without any talking. During field exercises Ranger students are given two MREs (Meal, Ready-to-eat) per day, but not allowed to eat them until given permission. This is enforced most harshly in Darby and Mountain phases. Since food and sleep are at the bottom of an infantryman's priorities of work behind security, weapons maintenance, and personal hygiene, it is generally the last thing Ranger students are allowed to do. As such, the two MREs are generally eaten within three hours of each other, one post mission, and the other prior to the planning portion of the mission. Though the Ranger student's daily caloric intake of 2200 calories might seem to be more than enough for the average person, Ranger students are under such physical stress that this amount is insufficient. The Ranger Training Brigade does not maintain weight information in the 21st century, but in the 1980s, Ranger Students lost an average of 25–30 pounds during the Ranger course.[19]

One interesting note here is that there is some biomedical researcher that suggests that women, with their slower natural metabolic rates and lower levels of the mentioned stress hormones, not to mention better adaptation to fluctuating weight and body fat rations, might actually have some advantage over men in these kinds of scenarios, provided they're in fit enough shape to handle the other physical stresses and exertion involved. Again, that's not really like sports. Bulky football players with a lot of muscle mass would probably be at a disadvantage here.

More generally, I don't know why it's surprising that 2 women passed, against thousands of men who graduated Ranger school. It might be surprising if there was a high percentage of women, but honestly, two women with the right kind of build out of thousands of candidates shouldn't be surprising.