Dogs are loyal friends of humans. Although they can't speak, they can communicate intra-species with rich behaviors. Among them, some of them are quite weird and obviously do not conform to human social norms. For example: When two dogs meet, "sniffing the butt first" seems to ha

Dogs are loyal friends of humans. Although they can’t speak, they can communicate intra-species with rich behaviors. Among them, some of them are quite weird and obviously do not conform to human social norms. For example: When two dogs meet, "sniffing the butt first" seems to have become a fixed habit of saying hello, but this does not mean that they are intentionally offending the other party.

In the world of animals, smelling butts is like a conventional etiquette. Cats, tigers, leopards, pigs, sheep, elephants, horses and other animals will show the same behavior. Research shows that the action of "sniffing butt" is like a human exchanging business card, which can help animals quickly obtain similar physiological information and facilitate understanding of the estrus status of the opposite sex. This is undoubtedly of great significance for animals' mating and reproduction.

Why do dogs have the habit of smelling their butts before mating?

Before analyzing this problem, it is necessary to understand the dog's olfactory system. Dogs have extremely developed olfactory abilities, with as many as .15 to 200 million olfactory receptors distributed in their nasal cavity, while humans only have 5 million . In terms of information processing, 30% of the brain mass of dogs is used to recognize complex odors, while only 5% of human brain mass is used to experience sniffing. The two have very different olfactory levels.

"Smell" has two meanings for dogs, because each dog has two olfactory organs. One is nasal composed of olfactory epithelial cells, mainly composed of olfactory cells, goblet cells, and support cells; the other is vomeronasal (VNO) located between the nasal cavity and the mouth, which can be simply understood as a narrow channel connecting the nasal mouth. Olfactory receptors are everywhere in the channel, and the brain and olfactory lobes are connected through 608 nerve bundles.

animal comunarus structure (blue tubular in the picture above)

comunarus is also called Jacobson's Organ ( Jacobson's Organ ). It is a relatively independent chemical sensing system and is also the main organ for dogs to recognize pheromone . When a dog's head is close to other similar butts, it is very likely to be for sensing pheromones.

This is because the animal has developed glands such as sebaceous glands, acroccone glands, anal glands, , and other glands. The external genitals of female animals are also at the tail, and the secretions of the glands are the carriers for transmitting information to the outside world. Near the dog's tail, the chemical signaling molecules have the highest concentration and are more likely to be perceived by other peers.

During estrus, hormones and secretions produced by the bitch's reproductive system increase, and the content of pheromones such as methyl parabenzoate is increased, which is very attractive to males, which can cause the latter to quickly enter a state of sexual excitation. In addition, by smelling your butt, you can also understand the gender of the other party , whether is currently in estrus, and whether is giving birth or pregnant in the near future, etc.

In addition to the identification of estrus status, the behavior of smelling butts is an indispensable and important part of dogs' social life, which is specifically reflected in two aspects:

first, which helps individuals identify . Scientific research has found that dogs' anal glands can secrete unique fluids, and the pheromones inside reflect a variety of information including diet, health, etc. With its developed olfactory system, dogs have powerful odor recognition and memory capabilities, which can recognize both their former playmates and their owners they have not seen for many years.

Second, it is conducive to determining dominance. According to dogs' social rules, dominant dogs are usually the first to sniff the other person's butt. When this happens, the dominant dog usually stands still to show obedience. By identifying pheromones, both parties can judge each other's threat and respond accordingly: launch an attack or acquiesce to accept.

cleft lip sniffing reaction: sniffing behaviors widely present in the animal world

I believe everyone should have understood that in the dog's world, smelling butts is not a manifestation of low quality, but a necessary quality for social experts.In addition to canines, almost all cats and ungulates in nature have similar phenomena. The most typical behavior is cleft lip sniff reaction , which is the famous Flehmen Response (Flehmen Response).

lip sniffing reaction refers to the animal's upper lip turning backwards, exposing its incisors, keeping the nostrils closed while inhaling and maintaining for several seconds. The study found that most animals' vomeronasal organs are not in the nostrils, but between the upper palate and the nasal cavity, and the opening of the pipe is located inside the oral cavity. Therefore, animals need to open their upper and lower jaws to better capture signal molecules, while closing their nostrils avoids the effects of other odors.

From a functional perspective, the cleft lip olfactory reaction helps to concentrate pheromones into the covoraria device above the oral cavity, greatly improving the information reception efficiency of animals.

So, what exactly does the cleft lip sniff reaction have?

First of all, it can help animals efficiently identify the reproductive state of the opposite sex. male animals sniff the urine or genital secretions of female animals through cleft lips sniffing reaction, and master the reproductive status according to the type of pheromone.

For example, scholars such as K.P. Bland once used sheep as an observation object and found that the cleft lip sniffing reaction of ram mostly occurs after ewe urinate, and the duration of the action ranges from 1 to 34 seconds . Another situation occurs when a ram sniffs the ewe's genitals, but in this case, it lasts very short, usually only 1~8 seconds .

Based on this, researchers speculated that the cleft lip olfactory reaction is the olfactory mechanism of rams confirming the reproductive status of ewes. The duration varies according to the sample being sniffed. The pheromone in urine or secretions all comes from the ewes' reproductive system.

Secondly, it is conducive to strengthening the parent-child relationship between animals. There is a phenomenon in that shows that the frequency of mares showing cleft lip sniff gradually decreases as they age, but peak frequency will appear again a few hours after delivery. The pups also exhibit high frequency of sniffing behavior during juvenile years, which is beneficial to strengthen the connection between the mare and the pup.

Finally, it will also be of great benefit to the survival competition of species. On the one hand, wild animals understand whether there are similar threats around them through cleft lip sniff reactions, and obtain competitor information through territorial identification signals (urine, secretions, etc.) to avoid them in a timely manner; on the other hand, sniffing behavior during estrus helps to actively search for the right opposite sex, and improves the success rate of individual pairing and population reproduction.

So, seemingly weird behavior may be the key to the survival of animals, and there is a profound way of survival behind it!

Can human women also produce pheromones?

The sex pheromone that is common in animals has been scientifically proven. Does this pheromone exist in humans? At present, this problem is still an unsolved mystery. Although a large number of studies suggest the possibility of the existence of human sex pheromones, so far no scientific team has been able to truly isolate trace samples.

Researchers believe that human sex pheromones are essentially chemical signal molecules, just like animals. But unlike animals, humans rely highly on vision to obtain external information, weakening the olfactory function, and odor plays a very limited role in social interaction. On the other hand, with the development of civilization, humans have developed the habit of taking baths and cleaning and hygiene from time to time, which has reduced their body odor. In addition, the effects of various perfumes and cosmetics have made human pheromones very hidden and almost undetectable.

Interestingly, comolarant is the direct receptor organ of pheromone, and the newborn fetus of humans have obvious colosar structure. However, as we grow older, the covoraria deep in the human nasal cavity gradually shrinks and deteriorates, and eventually disappears without leaving any trace.

Scientists have conducted an anatomical investigation on the bodies of 564 adults and found that 70% of the adults with do not have the structure of the covorarin, and the remaining 30% of the population with have also been highly degraded and do not have the substantial function of sniffing pheromones.

This seems to imply that humans, like animals, once had the ability to sniff pheromones, but in the long process of evolution, human ancestors invented languages ​​and tools, gradually rose to the top of the food chain, and formed a monogamous marriage structure. Over time, the help of covolar instruments no longer needed.

It is undeniable that humans are special existences in nature. They do not have a fixed estrus period like other animals, nor can they directly perceive the existence of pheromones. There are still many mysteries to be explored about humans’ understanding of themselves.