Human Pheromones: Linking Neuroendocrinology and Ethology (revisited)

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Human Pheromones Linking Neuroendocrinology and
Ethology (revisited)
International Society for Human Ethology,
2010 James V. Kohl Clinical Laboratory
Scientist ASCP, ASCLS, AMT JVKohl_at_bellsouth.net
www.pheromones.com
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Kohl, Atzmueller, Fink, Grammer (2001)Human
Pheromones integrating neuroendocrinology and
ethology.Neuroendocrinology Letters 22(5)
309-21.
Adapted for presentation from
and
Kohl (2007) The Mind's Eyes human pheromones,
neuroscience, and male sexual preferences
Journal of Psychology Human Sexuality, 18(4)
313-369. Concurrently published in the Handbook
of the Evolution of Human SexualityGuest editor
Michael R. Kauth Editor Eli Coleman. Taylor and
Francis, Inc.
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Support for the concept
Kohl, Kelahan, Hoffmann (2009) Human
pheromones increase women's observed flirtatious
behaviors and ratings of attraction 13th Annual
Meeting of the Society for Behavioral
Neuroendocrinology. East Lansing, Michigan.
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Linking neuroendocrinology and ethology

• Neuroendocrinology the study of the interactions
  between the nervous system and the endocrine
  system.
• Ethology the scientific study of animal
  behavior.
• The interaction between sensory input and
  hormonal levels appears to be a general rule in
  endocrine relationships underlying behavior.
  (LeMagnen,1982)
• In other words Sensory input effects hormones
  that affect behavior.

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What are Pheromones?

• Pheromones are species specific sensory input
  from the social environment that influence a
  definite behavior or a developmental process.
  Karlson Luscher (1959) Pheromones' a new term
  for a class of biologically active substances.
  Nature. 1959 Jan 3183(4653)55-6.
• e.g., by causing changes in levels of hormones

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Levels of Biological Organization

• Subatomic Particles Atoms Small Molecules
  Macromolecules
• Molecular Assemblies (e.g., genes) Organelle
• Cell
• Tissue
• Organ
• Organ system
• Organism
• Population Species Community Ecosystem
  Biosphere

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Sexual differentiation (Naftolin, 1981)

• This gene-cell-tissue-organ-organ system pathway
  allows natural selection to proceed at a pace and
  in directions keyed to environmental cues, like
  food odors and pheromones.
• The Gonads-Hormones-Behavior (G-H-B) model A few
  genes cause gonadal differentiation and the
  gonadal hormones are responsible for the more
  widespread and contemporary aspects of structural
  development and function in the brain and body.

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Gene-cell-tissue-organ-organ system

• In the G-H-B model, mammalian pheromones activate
  gene expression in gonadotropin releasing hormone
  (GnRH)-secreting nerve cells of tissue in the
  medial preoptic area of the anterior
  hypothalamus, which is the area of the brain that
  modulates the hypothalamic GnRH pulse.
• The brain is the most important organ of any
  organ system involved in behavior.

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Pheromones effect hormones and control sexual
behaviors
The effect of pheromones on reproductive hormone
status is mediated by GnRH neurons. GnRH plays
an important role in the control of sexual
behaviors via their link to reproductive hormone
status e.g., testosterone and estradiol and
sexual behavior that involves GnRH neurons.
Boehm, U., Zou, Z., Buck, L.B. (2005). Feedback
loops link odor and pheromone signaling with
reproduction. Cell, 123, 683-695. Pheromones
control definite behaviors by causing changes
in levels of hormones. Shepherd, G. M. (2006).
Behaviour Smells, brains, and hormones. Nature,
439, 149-151.
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Sex differences in behavior (Naftolin, 1981)

• Complex and highly variable social factors in
  humans often obscure the exact mechanisms of
  events that cause sex differences in behavior.
• However, see Mak et al, (2007) Neurons in the
  olfactory bulb that express GnRH receive signals
  from pheromones and send projections to the
  hypothalamus, which results in the release of
  luteinizing hormone (LH) and follicular-stimulatin
  g hormone (FSH) by the anterior pituitary.
  Together, LH and FSH control the release of
  steroid hormones, such as estrogen, that
  influence sexual behavior. (i.e., in the G-H-B
  model)

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Luteinizing Hormone The link between sex and the
sense of smell
Nature
SEXUAL DIFFERENTIATION
Pheromones alter GnRH-modulated neural
circuitry, odor hedonics, mood, memory,
motivation, cognitive behavioral state, and
potentiating responses to other stimuli, and
link Nature to Nurture via affective reactions
Nurture
PRENATAL
The influence of pheromones from the same sex or
from the opposite sex on postnatal sexual
differentiation
PRE- and POSTNATAL
GnRH Nerve cell Migration Olfactory
placode Olfactory Bulbs Limbic
System Hypothalamic GnRH
Pheromones
Aging Sexual Expression Sexual Identity Sexual
orientation Learning and Memory
From the same sex From the opposite sex
P H E R O M O N E S
Extrahypothalamic GnRH
Hypothalamus
Neuronal feedback
Positive
Negative
Male
Female
GnRH pulse frequency and amplitude
Cyclic
Tonic
extrapituitary effects
Pituitary LH / FSH
HPA axis
NEUROTRANSMISSION
HPG axis
Synaptogenesis Synaptolysis Apoptosis
Synaptogenesis Synaptolysis Apoptosis
Gonads
Adrenals
FSH
LH
Adrenal metabolites (androsterone) (etiocholanolon
e)
Testes (androgenic metabolites)
Ovaries (estrogenic metabolites)
Pheromones
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Sexual preference difference (1)
Hypothalamus
Medial preoptic area of the anterior
hypothalamus MPOA/AH MP-AHN
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Pheromones, GnRH, other Hormones and Behavior
One central neuronal (i.e., GnRH) pathway
links noradrenergic, dopaminergic,
serotoninergic, and opiodergic pathways, as well
as inhibitory neurotransmitters like
gammaaminobutyric acid and excitatory amino
acids like glutamic and aspartic acids and other
brain peptides including pineal secretions like
melatonin and corticotrophinreleasing hormone
and the complex interactions among them (e.g.,
the effects of hormones) to functional
species-specific influences, which are linked to
behavioral affect by the same hormone-secreting
cells, that pheromones directly effect.
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Pheromones and the hypothalamic GnRH pulse

• GnRH modulates the concurrent maturation of the
  neuroendocrine system, the reproductive system
  and the central nervous system.
• GnRH is required for LH release
• Increased GnRH pulse frequency favors LH release.
• The opposite sex pheromones of other mammals
  cause LH release.
• Axillary pheromones of men cause LH and mood
  change in women

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Prepubertal conditioning

• "There is now ample evidence that GnRH is
  secreted episodically in the prepubertal child
  long before physical signs of puberty appear
  (Jakacki et al., 1982). The onset of puberty
  therefore appears to be associated with an
  amplification of pulsatile gonadotropin
  secretion.
• Hopwood, N.J., Kelch, R.P., Hale, P.M., Mendes,
  T.M., Foster, C.M., Beitins. I.Z. (1990) The
  onset of puberty biological and environmental
  factors. In Bancroft, J, Reinisch, J.M. (eds.)
  Adolescence and Puberty. (pages 29-49) New York
  Oxford University Press.

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The neuroendocrinology of diverse sexual
preferences
Unconditioned stimulus (UCS) Pheromones Condition
ed stimulus (CS) visual, auditory, tactile,
gustatorycombined? The CS (e.g., visual input),
gains behavioral significance after being paired
with a biologically active UCS (e.g.,
pheromones). Odors/pheromones are the proximate
cause Hormone-driven preferences are their
effect.
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Affective primacy

• 1.Positive and negative affective reactions can
  be evoked with minimal stimulus input and
  virtually no cognitive processing.
• 2.Affect dominates social interaction and it is
  the major currency in social interactions
• 3.Affective reactions can occur without extensive
  perceptual and cognitive encoding. They are made
  with greater confidence than cognitive judgments,
  and can be made sooner.

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Affective primacy isOlfactory primacy

• Olfactory input from the social environment fits
  the assertions of affective primacy.
• For example, chemical cues allow humans to select
  for, and to mate for, traits of reproductive
  fitness that cannot be assessed simply from
  visual cues.
• The affect of pheromones on our emotions
• is linked to the effect of pheromones on the
  hormones of the hypothalamic-pituitary-gonadal
  axis an unconscious affect.

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Affect, olfactory primacy, and other sensory input

• Affect is conditioned in the presence of other
  sensory input.
• Mammalian neuroanatomical pathways link vision
  and olfaction. Cooper et al. (1994)

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Conditioning the response to visual stimuli (in
rats)

• Social-environmental odor cues, which males learn
  to visually associate with sexual activity, can
  be used to condition LH release.
• After minimal conditioning, an arbitrary odor
  ultimately will elicit a male LH response, even
  in the absence of odor previously associated with
  a female.
• Regardless of whatever other sensory input (e.g.,
  visual input) is involved, the functional
  significance of the conditioned change in LH
  secretion lies principally in the unequivocal
  demonstration that olfactory cues can activate
  the male hypothalamic-pituitary-gonadal axis in a
  way that mimics, in every respect, the activation
  achieved by exposure to a female. Graham
  Desjardins (1980)

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High Estrogen/Androgen ratios, physical features
Feminine features small jaw, full lips, large
breasts, narrow waist, shorter, higher vocal
pitch, light complexion, etc. AND THE
PHEROMONES OF WOMEN.
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Low Estrogen/Androgen ratios, physical features
Masculine features growth of the jaw, brow
ridges, center of the face from the brow to the
bottom of the nose, more facial hair, taller,
darker, more muscular, etc. AND THE PHEROMONES
OF MEN.
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Hormone-dependent features
Used with permission from Victor Johnson
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Poster session
J.V. Kohl L.C. Kelahan H. Hoffmann HUMAN
PHEROMONES INCREASE WOMENS OBSERVED FLIRTATIOUS
BEHAVIORS AND RATINGS OF ATTRACTION. Conclusions
The known effect of androstenol on luteinizing
hormone in women and what appears to be an
associated behavioral affect of androsterone meet
criteria that characterize human pheromones.
Kelahan-testing and results Hoffmann-professors
hip Kohl-study design
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Terms of Endeerment

• Cindy ... had gone alone to a portable commode
  hidden in a thicket to change her tampon, unaware
  that a young stag was nearby... Smelling her
  natural secretions, the male deer became
  sexually aroused. He bounded through the trees
  and knocked Cindy to the ground. Then while
  prancing up and down with his forefoot on her
  shoulder, the sexually excited deer sprinkled her
  with semen."
• Gibbons, D.L. (1989) Unusual case Sex in the
  woods. Medical Aspects of Human Sexuality, 23,
  10(Oct), 63.

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Sexual Odors / Food Odors

• It is important to remember that the animal
  perceives erotic odors in a manner analogous to
  his perception of food odors.
• Bloch, I. (1933) Odoratus Sexualis A Scientific
  and Literary Study of Sexual Scents and Erotic
  Perfumes. New York American Anthropol. Soc.