What is the meaning of love life

Evolutionary biology
Love knows very different forms

Can the dispute about the nature of love be resolved?

The search for the biological causes of human behavior is generally confronted with the problem that people are always also culturally shaped, that is, by example and upbringing. This also applies to our love and sexual behavior, because no social community does without influence here. In many cultures, partner choice is strictly controlled.

Some sexual inclinations are encouraged from an early age, others suppressed. So how can one, in view of the always present, cultural factors, identify possibly existing, genetically designed preferences for certain forms of coexistence?

The comparative anatomists of the 18th century already knew a solution to this problem: They had observed that there are close connections between the behavior of an animal and its physical characteristics. The way of life of a predator, for example, has different anatomical and physiological requirements than that of a herbivore. The same applies to sexuality and love life.

These, too, can be understood as complicated tools in which different parts are coordinated with one another and which cannot be changed at will without disrupting the functioning of the whole.

If it is correct that one can infer behavioral dispositions directly from anatomical and physiological features, then the problem of the cultural reshaping of human behavior can be elegantly avoided. The only necessary prerequisite would be that there are physical characteristics that are closely linked to certain behavioral dispositions. This is the case.

The commune

In this context, the weight of the testicles in relation to body weight is particularly meaningful and comparatively easy to measure. In mixed groups, the males have significantly larger testicles than in couples or in harems. Bonobos, for example, have testicles almost twenty times heavier than gorillas relative to body weight. Why is that?

If it is only about fertilization, small testicles like those of the gorillas are sufficient. However, if the females copulate with several males in quick succession, as with the bonobos, then the amount and composition of the sperm determine the victory in the fight for paternity. Then the penis is also often provided with scratches, shovels or flagella in order to remove the predecessor's sperm.

And what about people? Your testicles weigh around 40 grams with a body weight of 70 kilograms. This means that men have larger testicles than a male gorilla (30 grams at 170 kilograms), but much smaller than bonobos (135 grams at 40 kilograms).

From this anatomical fact alone, one can reasonably conclude that men are not made for a way of life in which women regularly have sex with different partners in quick succession.

The "commune" model, according to which sexual jealousy is a cultural artefact and which essentially reduces human love life to group sex, partner swapping and casual affairs, is accordingly a hardly feasible utopia.

In the case of existential threats or to celebrate extraordinary successes, there have always been collective sexual debauchery in the past and present. For biological reasons, it is unlikely that "free love" can be established as a system suitable for everyday use.

The harem

The situation is different when it comes to the question of whether people are monogamous or rather polygamous. In the western industrial nations, monogamy is considered the usual and only normal. However, this is by no means self-evident: only fifteen percent of all cultures today require this type of relationship! In comparison, 85 percent of cultures practice some form of plural marriage. Using just these numbers as a guide, one might suspect that humans are inherently polygamous.

What can be said about this from the perspective of biology? Are there physical characteristics that can be used to distinguish between monogamy and polygamy? The answer is yes. In mammals there is a statistical relationship between the difference in body weight of males and females and the deviation from the mating system of monogamy. As a general rule of thumb, the larger the average or maximum harem in a species, the greater the physical difference.

What can we conclude from this for the sexual behavior of men? On average, they are 15 percent heavier than women, i.e. humans are slightly less dimorphic than chimpanzees, for example. This makes them one of the mildly polygynous species. This conclusion is supported by a number of other biological characteristics that are coupled with hareming and polygyny in mammals. Under these conditions, males are selected for success in aggressive disputes rather than longevity. As a result, the mortality of male embryos is higher, which is why more boys than girls are conceived and born.