Why do animals (mammals) don't go through menstruation cycle?
602420
Yes, they do.  It's called "estrus, but is often referred to as being "in heat", especially when referring to a household pet.
543627
Sure, all do. Its called oestrus cycle in most animals. The menstural cycle is what it is called in primates. All primates (monkeys, etc) have a menstral cycle.
529466
the menstrual cycle stops for 9 months becuase the lining of the uterus (period) is being used to help the growing cell (baby) so it doesnt shed.
454709
Human are unique in having a monthly cycle.  Most mammals have a strict breeding season.  As set by that breeding season, other mammals will undergo a process like menstruation.  These would be whales, dolphins, seals, sea lions, sea otters, dugongs, etc.
109305
Ther are millions of species of land animals that don't drink water. Snails, frogs, earthworms and so on. These animals all absorb water directly thorugh their skins and through their food and and never drink.\n\nThere area also numerous mammals species that don't NEED to drink water but regularly do. Everything from kangaroo rats to house mice to koalas.\n\n\nSorry, the question doesn't have an answer.
105065
There are several.  One is the fact that plants and animals can be categorized.  If the had evolved, there would be no breaking point between various species.  There would be people with various ape-like characteristics.  The truth is that reproduction is limited to animals within groups.  A horse and donkey can make a mule (which cannot reproduce), but a dog and cat have different genetics which prevent reproduction between them.\nThere is also the problem of galaxies which all still act in clusters (gravitational attraction).  Calculating the escape speed based upon rate at which they are moving apart and masses of galaxies involved, the upper limit of 1 millions years for their existance is reached.  Evolutionists attempt to bypass this by stating that most matter in galaxies is invisible...the mass is only 10% of that needed to maintain the integrety of these systems.\nThe volume of meteoric dust on the moon was far less than NASA expected, prompting the first men on the moon to say, "I can see the soles of my shoes".
891372
Women are not more illogical than men.  One's ability to think logically and rationalize is an individual characteristic, and believing otherwise is buying into stereotypes.\n\nFemales can bleed for days and still live because they aren't bleeding from their actual veins.  What they release during menstruation is not just blood, but actually a number of things, all of which are, throughout the rest of the month, created by her body to create an egg that it is hoping to be fertilized and turned into a baby.  When that doesn't happen, the body sloughs it off and starts again.  The woman loses none of the actual blood pumping through her veins.\n\nHope that helps.
362950
Actually, your period is precipitated by a steep DROP in hormone levels that induces shedding of the lining of the uterus. Hormone levels peak just around ovulation (i.e., mid-cycle), and only remain high if fertilization occurs (if there is a pregnancy). In a normal cycle, where there is no fertilization, hormone levels drop steeply and this causes menstruation.
985479
Major causes of changes in the menstrual cycle are stress and pregnacy. But, if u'v done a pregnancy test and u r sure u are not pregnant...\n The other things that could disrupt ur menstrual cycle are changes in environment, change in weight and eating disorders, Hormonal contraception ,Eating disorders (anorexia, obesity, weight fluctuations, poor nutrition ,Stress ,Systemic illness (DM, hypothyroid,TB) ,STD ,Medications .\n\nThe best thing u could actually do is to see ur OB-GYN!
537538
Since the egg can't get past the 'knot' (it's usually cauterized though) it just sits in the fallopian tube until the body reabsorbs it. The sperm stays on the other side of the knot so they they never meet. Since the uterus is unaffected, you still have normal menstruation.
795780
some of them might hibernate. hibernation allows some small mammals to reduce their metabolism during times of scarce resources, such as winter. they accumulate body fat for a while, then it's like their system «shuts down»: their body temperature decreases, their pulse too, and they might breathe as few as 1 to 10 times a minute!\nhibernation is a real advantage because, when it's cold, it would take a lot more energy to keep normal body heat, consuming more nutrients, when, in fact, it's the time of year when it's more difficult to feed!
11651
While men produce estrogen and progesterone in small amounts (women produce testosterone in small amounts also), they do not have ovaries and they do not produce eggs.  Therefore, no men cannot have periods.
1164186
because they don't have ovaries, which produce estrogen and progesterone, which causes the ovaries to develop eggs for possible fertilization.
762403
Much like other land animals. "doggy style"\n\nThe female simply doesn't have her spikes sticking up in a defensive position.
486303
It sounds pretty normal.  Just keep track and if it doesn't get better go to the doctor.\n\nThe normal menstrual cycle in humans\nWomen show considerable variation in the lengths of their menstrual cycles, and the length of the menstrual cycle differs in different animals (see below).\n\nWhile cycle length may vary, 28 days is generally taken as representative of the average ovulatory cycle in women. Convention uses the onset of menstrual bleeding to mark the beginning of the cycle, so the first day of bleeding is called "Cycle Day one".
892123
I don't know for sure, but I reckon it's mediated by the primitive men's hunting expeditions, which they would have to synchronize with the phases of the Moon. So the men would mostly be away hunting, except in new Moon. Those women whose ovulations were synchronized with the men's comings and goings would have a reproductive advantage. The synchronization can't of course be a conscious decision (unlike the men's decision to go out hunting), but it may have been brought about by male pheromones (or maybe it was the result of natural selection, given the reproductive advantage?)\nThis does not explain why different women ovulate at different times and have cycles of somewhat different lengths, but if women stay closely together for some time, their cycles do converge, I think.\nIn modern life, women are not in synch with the moon exactly, but that's probably because there is no longer the men's hunting cycle to keep everything in synch.\nThe near-equality of the female and lunar cycles is probably not just a coincidence.
427914
During a menstrual cycle the uterine lining builds up in preparation for an egg to be fertilized.  If the egg is not fertilized, the extra tissues are not needed, so they are shed along with blood during a period.