Randy Ludwig

TNDY 402 FEB 14— 2011

The Biology of Love, Sex & Attraction

1. Types of LOVE2. Biochemistry of LOVE3. Applications4. Conclusion

OVERVIEW:

A few Stats:

Age of first marriage:

Women: 24.8 yearsMen: 27.3 years

The probability of first marriage by age 30: 74% for women 61% for men.

The probability of first marriage by age 40: 86% for women 81% for men.

(Goodwin, McGill, & Chandra, 2009)

A few Stats:

17% of women & 25% of men have not married by age 35.

12% of women have not married by age 40,

17% of men have not married by age 40.

The probability that men and women will marry by age 40 is over 80%.

(Goodwin, McGill, & Chandra, 2009)

If it feels different, it is different

TYPES:

1. Lust (Sex)2. Passionate Love (Infatuation/Romantic Love)3. Companionate Love (Attachment)4. Maternal Love

Lust/Sex:

TYPES:

1. Testosterone: (C19 H28 O2 )• Increases sexual arousal in men & women

2. Estradiol: (C18 H24 O2 )1. Associated with higher sexual activity in women2. Higher masturbation rates3. Preference for “manly” faces

3. Dopamine & Norepinephrine

• Non-selective sex, goodness of fit not important

Main Drivers:

1. Medial insula2. Anterior cingulate3. Hypothalamus4. Nucleus accumbens5. VTA

Key Brain Areas Involved:

Passionate Love:

TYPES:

1. Dopamine: (DA)2. Norepinephrine: (NE)3. Nerve Growth Factor (NGF)

• Exhilaration and euphoria

Increases in:

1. Serotonin: (5HT)2. Frontal Lobe3. Amygdala4. Parietal lobe

Decreases in:

1. Anterior cingulate2. Hippocampus3. Nucleus accumbens4. Hypothalamus5. VTA6. Caudate nucleus

Key Brain Areas Involved:

Excess DA & NE tend toreduce 5HT Obsession

Pleasure Centers In the Brain:

3. High amounts of dopamine are then released in the nucleus accumbens—equating to feelings of desire, importance, and pleasure

Orbitofrontal Cortex (OFC)

11. ________

1. ________

2. ________ 3. ________

4. ________ 10. ________

9. ________

8. ________

7. ________ 6. ________

5. ________

Corpus Callosum

Cingulate Gyrus Thalamus

Cerebellum

Hippocampus

MedullaPons

Amygdala

Pituitary Gland

Hypothalamus

Nucleus Accumbens

Companionate Love:

TYPES:

1. Oxytocin: (OXT)2. Vasopressin: (AVP)

• Calmer type of love, emotional bond• EX: grandparents married for 30 years

Increases in:

1. Serotonin: (5HT)

Decreases in:

• Chemically similar• Produced in hypothalamus• Released from pituitary gland

Maternal Love:

TYPES:

1. Oxytocin: (OXT)2. Vasopressin: (AVP)

• Parent & child

Increases in:

1. Serotonin: (5HT)

Decreases in:• Hypothalamus not

activated• Striatum is activated• Slight reduction in

frontal lobe

Brain implications:

Prairie Voles:

APPLICATIONS:

• Socially monogamous (mate with others at times)• High levels of OXT & AVP receptors

• If OXT & AVP blocked: they become promiscuous

Montane Voles:• Promiscuous• No long-term attachment• OXT & AVP injections in

montane voles doesn’t lead to monogamy—why?

• Students were approached by another student of the opposite sex, who said:

• “I have been noticing you around campus and I find you very attractive.”

• This was followed by one of three invitations:– “Would you go out with me tonight?” – “Would you come over to my apartment?” – “Would you go to bed with me?”

Clark & Hatfield (1989):

Go Out Go to Apt. Go to Bed

00

2020

4040

6060

8080

100100

About half of both sexes said “yes” to the date

Per

cen

t S

ayin

g “Y

es”

Go Out Go to Apt. Go to Bed

00

2020

4040

6060

8080

100100

About half of both sexes said “yes” to the date

Per

cen

t S

ayin

g “Y

es”

Go Out Go to Apt. Go to Bed

00

2020

4040

6060

8080

100100

Not a single woman said “yes” to the sexual invitation

About half of both sexes said “yes” to the date

Per

cen

t S

ayin

g “Y

es”

Go Out Go to Apt. Go to Bed

00

2020

4040

6060

8080

100100

Not a single woman said “yes” to the sexual invitation

About half of both sexes said “yes” to the date

Per

cen

t S

ayin

g “Y

es”

Go Out Go to Apt. Go to Bed

Men were even more likely to say “yes” to the sexual invitation

00

2020

4040

6060

8080

100100

Not a single woman said “yes” to the sexual invitation

About half of both sexes said “yes” to the date

Per

cen

t S

ayin

g “Y

es”

If men said “No,” then they typically apologized and/or offered an excuse such as “I’m dating someone”

Mate Preferences of Women

• Economic Resources• Good Financial Prospects• High Social Status• Older Men• Ambition and Industriousness• Dependability and Stability• Athletic Prowess• Good Health and Physical Appearance• Love and Commitment• Willingness to Invest in Children

Mate Preferences of Males

• Desire women who are:– Intelligent, kind, humorous, understanding, &

healthy– Similar in terms of values, personality, and

religious beliefs

In Addition...

• Youth

• A cue for fertility

Mate Preferences of Males

• Youth• Physical Beauty

• full lips, clear skin, smooth skin, clear eyes, lustrous hair, good muscle tone, & attractive body fat distribution

• Behavior: youthful gait, animated facial expression, & high energy level

– “Average” & symmetrical faces are more attractive

Mate Preferences of Males

• Youth• Physical Beauty• Body Fat and the Critical Waist-to-Hip

Ratio (WHR)– Universal preference across cultures...– .70 is optimal

References:

Clark, R.D., & Hatfield, E. (1989). Gender differences in receptivity oto sexual offers. Journal of Applied Social Psychology, 20, 771-782.

Fisher, J, Aron, A, & Brown, L.L. (2005). Romantic Love: an fmri study of a neural mechanism for mate choice. The Journal of Comparative Neurology. 493:58, 58-62.

Fisher, H.E., Aron, A., Mashek, D., Haifang, L., & Brown, L.L. (2002). Defining the brain systems of lust, romantic attraction, and attachment. Archives of Sexual Behavior. 31:5, 413-419.

Johnson, S. (2009). Addicted to love. The Brain. Winter, 50-55.Savulescu, J., & Sandberg, A. (2008). Neuroenhancement of love and

marriage: The chemicals between us. Nueroethics. !:31, 31-44Zeki, S. (2006). The neurobiology of love. FEBS Letters 581, 2575-

2579.