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To reproduce or not to reproduce, that is the question!
a review by Gert Korthof, 21 Sep 2003 (updated 24 Apr 2004)
Reproduction an incidental consequence of sex?
Biological Exuberance. Animal Homosexuality and Natural Diversity.
Defending homosexuality, attacking heterosexuality
Bagemihl defends homosexuality as a natural behaviour by documenting it extensively in mammals and birds.
He successfully refuted claims that homosexuality is unnatural ('unnatural' defined as 'not occurring in nature').
However, he does more than that.
Unexpectedly, he attacks the importance of heterosexuality.
He starts by pointing out that in nearly every population there is a group of nonbreeders.
I agree. For example in species with a harem, one male has access to the females in the harem
to the exclusion of all other males. In other species, often only the highest-ranking male mates with females.
But even in a heterosexual species without harem, males and females do not mate all the time.
For a great number of species mating has never been observed despite hundreds or thousands of hours of observation.
Often males and females live in separate groups. Young animals up to 3 - 5 years do not breed.
Male baboons have been observed copulating a pregnant or lactating female, a non-reproductive behaviour.
Reading the book, I started to realise that the group of non-reproducers is larger than the group of homosexuals (13).
It is the unusual perspective on evolution that makes this book interesting.
I could add to Bagemihl's list that in the human species, females are sexual receptive only 1-3 days a month (< 10%
of the time) and > 90% of copulations are in fact non-reproductive (see also Jared Diamond: 11 ).
Bagemihl makes another step in attacking heterosexuality by listing a number of 'bad things' about heterosexual behaviour,
such as the fact that males sometimes hurt females during copulation, things like rape and occasional heterosexual behaviour
among live and dead animals. His wish to marginalize sexual reproduction is demonstrated by this amazing statement:
"Although heterosexual mating can (and frequently does) lead to reproduction, this is often an incidental consequence rather than an overriding "goal" or ultimate purpose". Sexual pleasure is often a motivating force for heterosexual behaviour".
Bagemihl concludes that
homosexuality is not unique in the animal kingdom by virtue of its "failure" to lead to procreation.
True, but irrelevant
Bagemihl does not distinguish between the biological and the human perspective.
From the scientific perspective, reproduction is characteristic of life and evolution.
According to the definition of life of evolutionary biologist John Maynard Smith:
"Entities are alive if they have the properties of multiplication, variation, and heredity or are descended from such
Without reproduction every biological species on earth is doomed to extinction.
Viewed from that perspective, it does not matter how much time individuals spend
on mating or how many individuals of a population engage in sexual reproduction.
It is true, but irrelevant that not every heterosexual mating results in fertilisation. It is true, but irrelevant that 'animal life and sexuality are not organised exclusively around procreation'. The point is that every individual animal, including the homosexual individual, is the product of sexual reproduction. Indeed, there is one big certainty and that is a fact about the past: each individual animal (except rare parthenogenetic species) has a father and a mother and therefore is the product of a heterosexual event (3). Every male got his Y chromosome from his father and his X chromosome from his mother. The essence of being a diploid organism is having pairs of chromosomes, one form the mother, one from the father (3). This is also valid in species with harems. Whatever unequal contribution individuals have to the next generation, every individual originated from the union of an egg and a sperm. Bacteria reproduce by cell division and higher organisms do it by meiosis and fertilisation. Deep in their bodies, homosexual individuals, just as everybody else, reveal the signature of heterosexual reproduction. It even shows on the surface: a navel.
Pleasure and DNA
Sexual pleasure is often a motivating force for heterosexual behaviour, says Bagemihl.
Of course is sexual pleasure a motivating force for heterosexual behaviour.
But Bagemihl ignores the question why is sex fun?
A proximate cause of sex is pleasure (1).
The ultimate evolutionary cause is that the association of sex and pleasure increases the probability of reproduction.
About the male body:
Why does sperm contain the complete information for a new individual?
The DNA in sperm is not necessary for an orgasm.
If sex was only for fun, sperm could contain just proteins.
About the female body:
Why is the clitoris situated at the only place of the female body that enables sperm to reach eggs?
This makes sense from the point of view of reproduction.
If sex was only for fun and had nothing to do with reproduction,
then the clitoris could be anywhere on the female body (mouth, ears, nose, armpit, anus, navel).
But it is not. Explain!
The lions of Serengeti
The lions in the Serengeti plains of Kenya spend about 20 hours a day in rest or sleep, and only 1 hour a day on average in
Following Bagemihl's logic, one could dismiss the importance of food for lions by pointing out that:
(1) obviously lions are not preoccupied by hunting and getting a meal,
(2) getting a meal is an "incidental consequence rather than an overriding goal or ultimate purpose" of hunting,
(3) being built for the kill, the thrill of the kill is often a motivating force for hunting,
(4) not every hunt is successful,
(5) many members of the group do not participate in hunting,
(6) young animals are often chasing each other for fun and this has nothing to do with getting a meal.
We learn from the Serengeti lions that food is crucial for survival (just as sex and reproduction are crucial for the existence of the species) despite the fact that they spend only an hour a day in hunting. Furthermore, there are always non-hunters in a group, but they depend existentially on the hunters, just like homosexuals existentially depend on the reproduction of heterosexuals.
It is important to distinguish between proximate (physiological) causes and ultimate (evolutionary) causes. The proximate cause of food consumption and sex is an anticipated agreeable sensation in the brain, the ultimate cause is an increase of the probability of survival and reproduction.
Points of view
It is important to distinguish between the point of view of the individual and that of the species.
An individual can be a nonbreeder, a species cannot.
The point of view of an individual is a life's time.
The time scale of a species is millions of years. That is what evolution is about.
Furthermore, there is a distinction between individuals in a scientific theory (epistemology) and individuals in real life (ontology). As a person I can say that reproduction is not important in my life, but in the theory of evolution reproduction is crucial.
Another point of view is that of the mortal body (soma) versus the potentially immortal germline. In fact the body of homosexuals and heterosexuals does not reproduce. All your body cells are an evolutionary dead end. They are mortal. Only sperm and egg cells (the germline) are involved in reproduction. They are potentially immortal (12). In fact, our body has a division of reproductive labor!
There is still another point of view. Every human individual, and by definition every multicellular organism, is a community of cells. Each cell of our body originated by a process of cellular multiplication from one fertilised egg cell. This process is a form of asexual reproduction. It is basically similar to bacterial reproduction. The same process that single cell organisms use to reproduce, has built our bodies.
Death, sex and reproduction
Logically, the necessity to reproduce arises from the fact that every living organism dies sometime.
There is no eternal life, at least on this earth.
Species live for a few hundred million years, individuals only for a few decades.
So we need reproduction.
This logic is more fundamental than the logic of evolution.
Even if one believes in fixed species and denies evolution (creationists!), one still needs reproduction.
Death and reproduction characterise life on this planet.
Furthermore, this logic is independent of sex, because animals with external fertilisation (fishes, amphibia) do not need copulation to reproduce. The most fundamental thing of life is not how we reproduce (sexual or asexual, internal or external fertilisation), but reproduction itself.
Darwinism and reproduction
Darwin set out to explain the fact that organisms are so perfectly adapted to their environments.
This was a well-known problem in his time and the answer in his time was that the perfect fit of organism and its
environment was the work of God.
Darwin's explanation was that adaptation was created by natural selection.
By definition, natural selection is differential reproduction.
All organisms have the potential to produce more offspring than can possibly survive, but some produce more
surviving offspring than others.
Reproduction is not inherently important, but it is an indispensable ingredient of Darwin's theory to explain adaptation.
One of the core features of Darwin's theory, natural selection, simply does not work without reproduction.
As a biologist, Bagemihl ought to know this.
The second ingredient of Darwinism is mutation. Mutations are copying errors of DNA. Copies are made when a cell divides (reproduction). Without mutation, there is no heritable variation and natural selection can select nothing. Therefore, without reproduction no mutation and without mutation no natural selection, and without natural selection no evolution. As a biologist, Bagemihl ought to know this (14).
Sex and reproduction
In humans sex and reproduction are disconnected by natural as well as by unnatural means.
As Bagemihl rightly pointed out, in nature not every heterosexual act results in reproduction.
Humans added medical interventions.
Sex without reproduction is possible through the use of contraception.
Conversely, reproduction without sex is possible by in vitro fertilisation.
I hope nobody will conclude from this that there is no natural connection between sex and reproduction.
Purpose or effect?
A great deal of confusion can be eliminated when 'goal' and 'effect' are more clearly distinguished. Reproduction is not 'the goal of life'. Life is the effect of reproduction. Animals do not have a conscious purpose to reproduce anyway. We all depend on that 'incidental consequence' of sex. It just happens to be so on this earth that organisms are mortal and organisms reproduce. But that does not make death and reproduction 'the goal of life'. Although death and reproduction are not 'the goal of life', they are crucial to explain the existence of life on earth. And that is what Darwinism does.
Science and values
What is valuable? What is a meaningful life? Bagemihl suggests that we should evaluate homosexuality and other forms of
non-reproductive behaviour not in terms if its biological usefulness, but in terms of its intrinsic value.
However a scientific theory has nothing to say about values at all.
Irrespective of the biological or evolutionary 'value' of behaviours, people value those behaviours as good or bad.
No higher human goal is involved in reproduction. For humans there is no moral obligation to reproduce.
Therefore, it makes no sense to defend or attack statements like "reproduction is the ultimate purpose of life".
If Bagemihl would see this, he would not have the urge to attack heterosexuality.
Evolutionary theories about non-reproductive behaviour do not say anything about
the meaning or value of that behaviour. On the contrary.
As evolutionary biologist George C. Williams noted:
"With what other than condemnation is a person with any moral sense
to respond to a system in which the ultimate purpose in life is to be better than your neighbor at getting
genes into future generations." (4).
Surprisingly, Bagemihl did not notice that Catholic priests value celibacy much higher than reproduction.
Gregor Mendel, the monk in the monastery garden, the father of genetics,
made an everlasting contribution to science, but he did not pass on his genes to the next generation.
In chapter 6 Bagemihl explains his new paradigm: biological exuberance. His new paradigm is 'post-Darwinian Evolution'
and is a mix of Gaia, chaos theory, indigenous cosmologies, and Georges Bataille.
I found it unconvincing, vague, and irrelevant.
Bruce Bagemihl is the first critic of evolution who rejects the all-importance of heterosexual reproduction,
and thereby implicitly reproduction.
The existence of sexual reproduction, in contrast to asexual reproduction, is an outstanding, unsolved problem in
evolutionary biology (8),
but the importance of reproduction itself is unquestioned.
Bagemihl did not make clear what exactly 'post-Darwinian Evolution' means.
Does he reject the core evolutionary concept natural selection?
Selection is 'differential survival and differential reproduction'.
Without selection no evolution. Selection implies reproduction.
Bagemihl did not explicitly reject evolution. Therefore, to be
logically consistent, he must accept natural selection and reproduction too.
In fact, Darwin stressed that there is an over-reproduction in nature, which causes a struggle for life.
Bagemihl could have defended homosexual behaviour as 'natural', without attacking the logical necessity and the fact
Bagemihl would be surprised to learn that modern sociobiology has refuted the old idea
'that sex is a fundamentally benign, cooperative venture designed to perpetuate the species' (5).
Bagemihl says cognitive adherence to Darwinian theory blinded observers to common homosexual and transgender
behavior in the animal kingdom (6). This is undoubtedly true (9).
But the solution is not to reject evolutionary biology, but to eliminate prejudices.
It is a distortion of reality to say that homosexual behaviour is unnatural (defined as 'not occurring in nature'),
but it is also a distortion to say that reproduction is unimportant in biology.
To explain life, evolutionary biologists are fully justified to give reproduction a central place.
For example, we could not understand the devastating effects of the Human Immunodeficiency Virus, without understanding its
awfully efficient reproductive power (7).
Strong parts of the book are the encyclopaedic documentation of homosexual behaviour and the use of those data
to evaluate hypotheses and prejudices about homosexual behaviour.
Weak points are biased descriptions and interpretations of homo/heterosexual data
and a failure to acknowledge that
one cannot explain the existence of life on earth without reproduction, and that one cannot explain biodiversity
and adaptation without differential reproduction.
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|Copyright ©G. Korthof 2003||First published: 21 Sep 2003||Updated: 22 Apr 05 Notes/Links: 28 Aug 2013|