We share the vast majority of those genes with the mammalian species, but only humans (and occasionally our close primate relatives like chimps and bonobos) kiss.
Many animals actually do engage in kissing-like behaviours to show affection. These behaviours are so diverse, from dogs sniffing and licking potential mates, to elephants putting their trunks in each other's mouths. However, one animal kisses just like we do: the bonobo ape.
If we look in the animal kingdom, we'll see that kissing is unusual. Most animals don't kiss as such, but many of them exhibit similar affectionate behaviors such as licking, hugging, touching faces, and many other habits of social approach. However, our closest relatives, chimpanzees and bonobos, do kiss.
While they do kiss with their lips, their smackers are narrower and don't turn out like ours do. Researchers speculate that this anatomical difference could mean that kissing for chimps is not particularly intimate, but rather an expression of connection like the human hug.
Some scientists believe that kissing is a learned behavior, since roughly 10 percent of humans don't kiss at all and considerably fewer kiss with romantic or sexual intent. Others believe kissing is instinctual and rooted in biology.
Indeed, some 650m people—or about 10% of the world—don't partake at all. Until contact with the West, for example, kissing wasn't practiced among Somalis, the Lepcha people of Sikkim or Bolivia's indigenous Sirionó.
During the later Classical period, affectionate mouth-to-mouth kissing was first described in the Hindu epic the Mahabharata. Anthropologist Vaughn Bryant argues kissing spread from India to Europe after Alexander the Great conquered parts of Punjab in northern India in 326 BCE.
If a human were indeed inclined and able to impregnate a monkey, post-zygotic mechanisms might result in a miscarriage or sterile offspring. The further apart two animals are in genetic terms, the less likely they are to produce viable offspring.
Some researchers believe that kissing began millions of years ago as a result of mouth-to-mouth feeding. Some researchers believe that kissing began millions of years ago as a result of mouth-to-mouth feeding, with mammal mothers chewing food and then "forcing it" into the mouths of their young.
First Recorded Kiss (circa 1500 B.C.)
Whatever the case, the earliest known written mentions of it are in Vedic Sanskrit scriptures circa 1500 B.C., according to research by Vaughn Bryant, an anthropology professor at Texas A&M University.
Not only do animals enjoy the deed, they also likely have orgasms, Bekoff said. They are difficult to measure directly but by watching facial expressions, body movements and muscle relaxation, many scientists have concluded that animals reach a pleasurable climax, he said.
The question of whether animals fall in love in a way similar to humans has vexed researchers for years. While it is not known if animals experience romance exactly the way humans do, recent studies show that for some animals there is indeed the capability to love.
The human-animal bond can be observed in a variety of settings. Working animals, especially, are known for their relationships with their human handlers. Emotional support, therapy, and service animals provide comfort, offer security, and perform daily tasks to help their owners through life.
Most people can't focus on anything as close as a face at kissing distance so closing your eyes saves them from looking at a distracting blur or the strain of trying to focus. Kissing can also make us feel vulnerable or self-conscious and closing your eyes is a way of making yourself more relaxed.
The most widely accepted explanation is that American and British servicemen in France during World War I were struck by the more passionate way French women kissed. When they returned home, they introduced 'French kissing' to their partners and lovers.
For starters, the pleasure that you get from making out is literally the result of a hormone, oxytocin, being released when you're kissing. Not only is it a chemical that makes you feel generally happy, but, as psychotherapist Jonathan Alpert told Bustle, "This [also] creates a bond and a feeling of connectedness.
Naturally, a human cannot impregnate a pig as there are many reproduction barriers between them. Naturally different species cannot breed as there are many reproduction barriers most importantly there are genetic barriers.
The sexual connotations of the phrase "make out" appear to have developed in the 1930s and '40s from the phrase's other meaning: "to succeed". Originally, it meant "to seduce" or "to have sexual intercourse".
One of the most passionate ways to kiss, a French kiss tops the list of kisses! An intimate and erotic move, it is surely to set your partner's mood for some romance. Start by tilting in and locking your partner's lips with yours. Remember to go with the flow, rushing through this divine moment can ruin the feel of it.
Guinness World Record for longest kiss: Ekkachai Tiranarat and Laksana, of Thailand, hold the Guinness World Record for the longest continuous kiss that lasted a total of, 58 hours 35 minutes and 58 seconds.
The Middle East and India are two parts of the world where you'll encounter the strictest public display of affection laws. Kissing in public is illegal in Dubai, and couples have been arrested for excessive PDA in Egypt.
In most of the Western world, such as Western Europe, Australia, New Zealand, Canada, the United States, and Latin America, it is very common to see people holding hands, hugging and sometimes kissing in public.