One of the myths that permeates human society in almost all cultures is the belief that humans are special or different in kind from other animals. We believe that our intelligence (or worse, our “soul&rdquo makes us separate from – and higher than – the animals. In fact, the very language we use betrays our belief that we are better than them. We say that someone is acting like an animal, and we don't mean it in a good way. We urge our fellow humans to give up the base animal instincts and pursue something higher. In so many religions, we hear admonitions against giving in to our “base instincts.” By this, most religions mean lust, sex, and desire.

In reality, if we are to have a chance of truly understanding ourselves, we must dispense with this belief. From early childhood, we are told that we are special. We are told that god, or the universe, or karma has some “special plan” for us. When we become adults, we build immense monuments and fight wars and bulldoze forests in the name of human supremacy. Despite all this, we are not different from animals. We are animals.

Unfortunately, this is where a lot of non-critical thinkers stop. Often, they are stopped by their own conscience, but if they are not, it's almost certain that a friend or immediate family member will do their best to talk them out of such nonsense. After all, they will argue, it's obvious that humans are different than animals. Why, we build hospitals and make music and art! We love, and are loved in return. We tell our grandchildren about how our grandfathers fought in the War to End All Wars, and how they knew that there was something bigger than themselves, so they did what they had to do.

This response, and the seemingly inevitable defeat of anyone who tries to argue against it, is clear evidence of just how strongly our myths can take hold, and how much of an impediment to critical thinking they can be. Once we examine what it is to be an animal, and how animals differ from each other, we will see that it's not only possible to be an animal and experience love, honor, duty, and beauty, it's actually impossible to think of it any other way. We must be animals if we are to experience such things.

Before I continue, I must caution against all-or-nothing thinking. Though we are animals, and are not different in kind from other animals, it does not follow that we are not different in degree. Only a fool would argue such a thing, though it is amazing how many theists and bad critical thinkers will argue vehemently against this position, as if defeating such a pitiful argument makes them right. This, by the way, is called a strawman argument. Whenever someone portrays their opponent as making a ridiculous argument, only to argue against it (even though the opponent never actually made the argument in the first place), we say that they have created a strawman.

One of the most essential differences between humans and other animals is our brains. We are among only a handful of creatures on earth who are capable of language, and our capacity for abstract thought is unrivaled. Nevertheless, this difference is a difference of degree. Our ape-like ancestor was smart enough to use tools, and may have possessed some rudimentary language skills, as do modern day chimps and apes. Dolphins and whales communicate through clicks and songs, respectively. Our intellect and capacity for language have allowed us to make incredible leaps in the last hundred millenia, much greater leaps than any other creatures, but we are not the only intelligent creatures on earth.

Another difference between humans and other mammals is female sexuality. Unlike most mammals, human females do not experience estrous. In most animals, female sexual response is governed by the four phases of estrous. During Proestrus, one or more follicles in the ovary begin to grow. This can last for one day, or as long as three weeks or more. The lining of the uterus starts to develop. (Incidentally, there is sometimes vaginal discharge that is mistaken for menstruation.) During proestrus, females are not sexually receptive.

Estrus, often called, “in heat,” is when the female becomes sexually receptive, and is often accompanied by outward physical changes and involuntary or reflexive sexual behaviors, most notably the lordosis behavior, in which the hindquarters are elevated and the spine undergoes ventral arching.¹ In some animals, there is an intermediate phase, known as inerestrus, after which estrus resumes again if copulation has not occurred.

During Metestrus, the signs of estrogen stimulation subside, and the uterine lining begins to break down. Finally, during Diestrus, the lining of the uterus is absorbed into the body and reorganized for the next estrus phase. After the entire estrous cycle is complete, there is usually a period of inactivity known as Anestrus. There is no sexual receptivity in females during this period. The duration varies greatly, but is usually based on seasons. Some animals go into heat several times a year, while others only get one or two chances.

Contrast this with humans, who undergo menstrual cycles. Instead of reabsorbing the uterine lining, humans experience eumenorrhea, which is the regular discharge of the uterine lining, sometimes with the endometrium lining. You know this as the menstrual cycle. There is not a clear answer to the question of why humans evolved differently than almost every other mammal. It has been suggested that the energy cost of absorbing and then reforming the uterine lining is more than that of simply creating a new one. Also, it is possible that the discharge of the uterine lining also cleanses the body of sperm-borne pathogens. Finally, it has been theorized that menstrual synchrony, or the tendency of cohabiting females' periods to align, was beneficial to societies in which the hunters went out on long expeditions, leaving the women alone and sexually unresponsive, only to have the best chance of receptivity and ovulation when the entire group returned.

Human females have varying degrees of sexual receptivity during all stages of menstrual cycle. Though many women are most receptive to sexual intercourse while they are most fertile, some level of sexual interest is maintained for virtually the entire cycle. However this evolved, it was clearly one of the catalysts for the development of human culture as we know it. Human sexuality is not simply reproductive. In fact, considering the fact that women are fertile only a few days a month, but can have sexual intercourse multiple times per day virtually every day of the year (Yes. I know. Make your own joke here.), it would be incredibly surprising if non-reproductive sex wasn't a big part of our culture.

As we developed language and began to form complex relationships, we naturally began to make long term predictions which were impossible for other, less intelligent animals. Men recognized that repeated sexual advance was more successful with females who had already consented once. They learned the value of impressing women. Women learned that men had learned the value of impressing them. The snowball was rolling downhill. More intelligent men found clever ways to impress women. The women liked it, and the resulting children tended to be more intelligent. Men and women recognized the fact that sexual intercourse felt good. Those whose brains released more endorphins found that it was beneficial to return to the same mate often. Other people noticed. Jealousy was born. The snowball was getting huge. Culture was inevitable.

In any case, this is one very important way in which humans are quite different from other animals. Whether we learn the exact evolutionary path we took to get here, we must look at this difference critically if we are to understand our own sexuality. In fact, it is this very thing – our ability and desire to have sexual intercourse outside of procreation – which makes us different from animals. Contrary to the common conception, our sex drive is not similar to those of the lower animals. It is substantially different, and might just be the catalyst for our entire culture! When we describe sexuality as a base, animalistic drive, we don't recognize the irony, for we misunderstand the simple truth: Our sexuality is what makes us human!

If you will forgive me a bit of wild speculation, it is not difficult to imagine an early religion forming around the mystery of the female. They regularly bled, and always with the tides and the moon. They did not suffer as men when they bled. Before man had discovered the link between sexual intercourse and babies, it must have been even more miraculous! Women had the power to make life, and they pulled from their bodies both men and women. It would not have been lost on them that all these abilities seemed to coincide with the passing of the moon and the movement of the water. Any wonder that they made idols of women, and that many of the most ancient relics of long forgotten civilizations indicate female worship?

Here, we encounter our next round of skepticism and naysaying. Some will argue that the origins of our sexuality do not have any bearing on the harsh realities of modern civilization. We have STDs. We have divorce, adultery, rape, and sexual perversion. We have advanced beyond primal man, and we have a responsibility to act as a higher being, for we understand the dangers inherent in our sexuality, even if we grant the role it had in forming our civilization.

Again, I must caution the reader against all-or-nothing thinking and strawmen. Remember, as critical thinkers, we must always ask ourselves if we are answering the questions that have been asked, or if we are assuming things based on our own prejudice. Only the naïve and the arrogant believe they are not prejudiced, and we must strive to expose our own predispositions if we are ever to overcome them. At no point in this essay have I advocated a particular way of defining sexual roles. I have simply provided facts with regard to the origins of our sexuality. We must learn more of ourselves before we can address the very real problems involved with human sexuality. Knowing about our past is fine, but we must also address our present.

(To be continued)

1Males of some species experience lordosis, especially when they are receptive to homosexual advances.