Why we do it

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Why we do it
Paolo Crocchiolo

• The Glance of Science at Sexuality

With the collaboration of James Weinheimer
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Mundi genitalis origo...(Lucretius, De Rerum
Natura, V)
REPLICATION
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Duplication

• Primeval emergent property of life, based on
  chemical/physical attraction/repulsion
  mechanisms
• Phenotypes are shaped by natural selection as
  environment-adapted envelops of their underlying
  genes
• Mutations grant the necessary degree of
  biodiversity

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In sese genera ac varias docet...(Lucretius, De
Rerum Natura, II)
SEX
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Genders / Sexual Differentiation

• Sexual reproduction is a duplication modality
  that grants a richer genetic mixture, hence a
  higher degree of biodiversity counterbalancing
  the lower reproduction rate of more complex and
  fewer mutations-accumulating organisms

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Different kinds of sexual reproduction

• Bacteria conjugation gene exchange based on
  chemical affinity, still closely resembling
  simple duplication

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• Plants hermaphroditism - adaptation to vectors
  (wind, insects) spreading and carrying their
  seeds and pollens

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• Animals sexual reproduction consists of the
  fusion of separate gender-specific genotypes
  which underlie their correspondingly separate
  sexual traits-carrying phenotypes

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Sexual encounters1 Prerequisite
movement2 Prerequisite attraction
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MOVEMENT

• Development of the neural system primarily meets
  the animal phenotypes need to move around in
  space
• Immobility is the price plants have to pay for
  the privilege of chlorophyllan photosynthesis
  endless search for food is the price animals have
  to pay for the privilege of mobility
• However, in addition to food-dependent growth,
  movement also serves sexual encounter-dependent
  reproduction

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Non ita certandi cupidus quam propter
amorem...(Lucretius, De Rerum Natura, III)
ATTRACTION
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Pleasure Pain

• Emergent properties of the neural-hormonal system
  
• Physical-chemical affinity/repulsion gradually
  convert into the more sophisticated
  positive/negative hedonistic tones, functioning
  as emotional bridles that unconsciously guide us
  in our perceptions and in our actions
• Without neural-hormonal system-based hedonistic
  tones, any ethics and aesthetics would be
  meaningless

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Vital Illusions

• In all living beings endowed with a
  neural-hormonal system, natural selection ends up
  associating the rewarding sensation of pleasure
  with perceptions/behaviours directly or
  indirectly leading to, and enhancing, survival
  and reproduction, and the punishing sensation of
  pain with perceptions/behaviours directly or
  indirectly hindering, or threatening, survival
  and reproduction

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Philosophical puzzle

• Pleasure and pain do not exist in themselves
• They are natural selection-driven positive and
  negative hedonistic tones that we conventionally
  and unconsciously link to physical-chemical
  reactions between certain mediators and certain
  receptors of our brains/bodies

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• So, how do living beings conventionally interpret
  quantitative physical-chemical signals and
  translate them into (arbitrary) qualitative
  judgements?
• We do not know, nor do we understand how it
  happens, but it does happen, and it works!

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Instincts

• Instincts may be defined as transmissible
  associations of pleasure/pain sensations with the
  resulting survival and reproduction-enhancing
  behaviours

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Hominum divomque voluptas...(Lucretius, De Rerum
Natura, I)
PLEASURE
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Instinctual attraction serving sexual encounters,
hence reproduction

• Natural selection tends to propagate the genes
  that, inducing pleasure-associated behaviours,
  best predispose to, and facilitate, the sexual
  encounters of their phenotypic carriers/envelops
• In this perspective, birth itself turns out to be
  a side effect of pleasure

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Id facit exiguum clinamen...(Lucretius, De Rerum
Natura, II)
MUTATION
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Progressive sexual roles separation
specialization process

• Anatomical, physiological and psychobiological
  structures of the two genders are mouldable,
  tailored by natural selection to the specific
  reproductive needs of their respective
  genotype-containing gametes

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• Instincts and behavioural patterns of the
  gender-specifying phenotypes are in fact selected
  as a function of their underlying genes
  propagation capacities
• In sum, male and female bodies and minds turn out
  to be shaped in such a way as to ultimately
  enhance their gametes reproductive potential

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• Natural selection increasingly widened the gap
  between bigger and bigger female gametes, and
  smaller and smaller male gametes
• In the ensuing struggle for supremacy,
  organules-retaining females ultimately prevailed
• As a consequence, the small, nude males are
  obliged, since ever, to frantically run after the
  big coated females

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Ovum and Spermatozoa
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• As a result, male phenotypes can afford to waste
  their in excess produced, amply redundant sperm
  while female phenotypes are induced to jealously
  protect their precious genetic investment, as
  they can only rely on a limited production of
  gametes

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REPERCUSSIONS on theTWO GENDERS
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Belli fera moenera Mavors...(Lucretius, De Rerum
Natura, I)
EXCITABILITY-COMPETITION
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Male genotypes are selected that induce, in their
phenotypes

• higher sensitivity ( excitability) to, and lower
  specificity of, triggering stimuli
• competition among spermatozoa of the same carrier
  and between sperms of different carriers
• high reproductive variance

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Sperm Wars

• Smell of sex the most potent male aphrodisiac
  (analogy with sharks, lions, and their
  excitability to the smell of blood)

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Velarint tempora Musae...(Lucretius, De Rerum
Natura, I)
FINETUNING-SELECTIVITY
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Female genotypes are selected that induce, in
their phenotypes

• higher selectivity in the choice of their sexual
  partner
• higher excitability threshold to, and higher
  specificity of, triggering stimuli
• increased fine-tuning of intuitive
  perception/feeling skills and capacities
• no waste, but instead selective use, of genetic
  resources

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Female Orgasm

• The presence of clitoridian pleasure-signaling
  tissue (embryogenetic homologous to penile
  tissue) offers the potential opportunity to
  modulate and adapt the response to exciting
  stimuli, tailoring it to the selective pressure
  of environmental factors (including physical, but
  also socially/culturally-biased emotional
  components)
• I.e., the same pleasure-triggering tissue is used
  in function of the gender-specific carriers
  psychobiological needs

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• REPLICATION
• SEX
• ATTRACTION
• PLEASURE
• MUTATION
• EXCITABILITY-COMPETITION
• FINETUNING- SELECTIVITY

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So, why do we do it, darling?
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I know why
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The answer is love
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Titian countryside concert
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Tintoretto Danae
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Marilyn Monroe
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Marilyn
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Renoir bathing beauties
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Leonardo Leda and the Swan
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Ingres odalisque
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Reni Susan
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Titian Venus
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Guercino Venus and Mars
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Venus de Milo
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Antinoos Delphi
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Paestum the Symposium