It is said that birds do not pee, some people think it is a rumor, but birds really do not pee, and bird droppings are very thin, if the car is parked under the tree for a long time, basically there will be bird droppings. The gutters are sparse, and it is always said that there is bird droppings in the car, but no one says that there is bird urine, because they really do not urinate.
Birds' reproduction, defecation are from a thing called cloaca, so eggs are generally not recommended to eat raw, there are many bacteria in the intestine, and eggs are out of the cloaca, it will mix urine, feces, the reason why eggs can hatch normally, because eggs have a multi-layer membrane structure, allowing eggshells, membranes to breathe while preventing external bacteria from entering, of course, too long, bacteria will eventually enter, so that eggs deteriorate and stink. Birds' urine is also excreted in one piece, so bird droppings are very rare.
Human beings are very different, human women's stool, urine and reproductive tract are separated, males are also separated, but the male reproductive tract end and urethra are connected, the big is another channel. If only from the perspective of convenience, the excretion and reproduction of birds are very convenient, after all, they are all together, just a channel, which avoids some unnecessary infection problems, and it is also very convenient, unlike humans who urinate separately, different defecation needs have different ways, making it very troublesome.
In fact, from the perspective of reproduction and evolution, human beings have never known that birds hundreds of millions of years ago and modern times were an ancestor. About 400 million years ago, organisms began to climb on land to survive, when the Earth's atmosphere was high in ozone levels, which could block most short-wave ultraviolet rays. Modern times believe that all terrestrial vertebrates are descendants of coelacanths, which is an ancient teleost fish whose spine runs from the neck to the tip of the tail, which is the same as that of modern humans and other animals, and the reproduction of fish is also a three-in-one pattern of birds.
Organisms not only reproduce but also mutate, and mutation provides raw materials for evolution. Over more than 400 million years, the physiological structure of some organisms inherited the coelacanth that first climbed onto land, and some gradually evolved and became different. Species are genetically diverse, but there are certain similarities, similarities are derived from heredity, diversity comes from variation, and variation is evolution to a certain extent. This is the result of biological evolution and differentiation, the starting point is the same, and later because of the different environments in which they are located, the results of evolution are different.
The separation of the three in humans (the end of the male reproductive tract and the urethra together) is the result of long-term evolution. In terms of the number of openings, an opening has more advantages, because the physiological structure is simpler, more energy-saving, and the three-in-one less caused the invasion of bacteria. The separation of the three increases the risk of bacterial invasion, and the separation of the three is more complex in physiological structure, more energy-consuming, and unfavorable to the biological impact from the perspective of energy saving.
The advantage of the three openings is that the reproductive efficiency is higher, like birds, fish, a lot of eggs at one time, especially fish, but the vast majority of eggs, newborn offspring are eaten by natural enemies, fish lay 10,000 eggs, and eventually 100 can survive is not bad. And the pattern of the cloaca is not conducive to mating, fish directly discharge germ cells into the water, which also causes a lot of waste; while the cloaca of birds, relatively evolved, males have a spiral similar to the structure of the genitals, but it is also difficult to excrete germ cells deep into the female reproductive tract.
People on farms may be more aware that many eggs are produced at once to hatch, but a considerable number of them are always unfertilized and cannot hatch. In such a structure, men and women are compatible, women excrete one egg a month, and men excrete many sperm a month. The right age (around 25-32 years old) is easy to get pregnant, and it is easy to get pregnant if you don't take good measures at this time. Relatively high efficiency, although human women generally only release one egg at a time, but the efficiency of sperm-egg binding is relatively high.
In biological evolution, the need to survive and reproduce takes precedence over the need to save that little bit of energy, because that little bit of energy can be easily invaded by bacteria by eating more and more frequent dietary supplements, which is not the highest priority. On land, fish certainly don't work the way, germ cells have to die; birds are more closely related to fish and humans, but human women only lay one egg at a time, and germ cells are kept in the reproductive tract for a limited time, which is not very suitable for birds.
Although it is defective, but the relative reproductive efficiency is very high, if only the reproductive ability is counted, women from teenage to nearly 50 years old can naturally give birth, which is about 30 years, can give birth to a lot. Of course, women are not fertility tools, and how much a family has depends on the needs of the family and the wishes of women. But just from the perspective of reproductive ability, human conception is quite efficient. Human hunting methods also ensure the demand for food, and the development of medicine is to solve difficult diseases, so some defects do not affect the survival and reproduction of human beings.