exam 1 pt2 Flashcards

1
Q

MHC & Smell: Evolutionary Argument

women

A

Reproductive success: Women

Getting pregnant costs women a lot

Women may be more attuned to picking reproductive opportunities that may produce offspring that are immunologically fit and more likely to survive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

MHC & Smell: Evolutionary Argument

A

Men lack a more sensitive sense of smell that might distract them from taking advantage of a reproductive opportunity

Women may use it to select mates
When a guy’s a genetic mismatch for you, the funny smell may well be your body sending up a red flag

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

MHC Compatibility & Infidelity

A

Garver-Apgar et al. (2006)
Asked 50 long-term couples a series of questions:
How attracted were they to their partners?
How satisfying were their sex-lives?
How much did they fantasize about having other sexual partners?
Have they had any affairs?
If so, when and how often?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

MHC Compatibility & Infidelity (Findings)

A

The average couple has 20 % of their MHC variants in common
The more MHC variants women shared with their partners:
The less sexually attracted she was to him
The more she rejected his sexual advances
The more she fantasized about other men
The less aroused she felt when having sex with him

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

MHC Scent Preferences & the Pill

A

Want to hear something wacky that happens when you’re on birth control pills?
Your scent preference inverts and you actually PREFER the smell of men whose MHC’s are SIMILAR to your own!

Researchers uncertain why normal preference pattern get reversed
Likely has something to do with the lack of hormonal fluctuations ovulating women normally experience (you don’t ovulate if you’re on the pill)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What about Pheromone Sprays?

A

There’s a pretty booming industry selling “pheromone” sprays
Producers claim will “unleash your lover’s animalistic side!”

Given that female response to male testosterone derivatives is based on MHC, it doesn’t seem realistic to expect any one smell to do the trick

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Bacterial By-Products

A

Microbes in sweat glands break down sex-hormones and MHC-related proteins

The resulting body-odor 
	is at least partly 
	bacterial by-product
The musky smell of male 
	sweat comes from the 
	bacterial breakdown of 
	androstenone
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Enter the Vomeronasal Organ (VNO)

A

What mammals use to detect pheromones
Two pits located in the nasal septum between the nose and the mouth

(PEOPLE HAVE THEM TOO)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How PHERONMONES WORK

A

1-Our bodies naturally secrete fluids through glands in our body that contain natural pheromones

2-The vomeronasal organ detects the pheromones and sends a signal to the olfactory nerves.

3- the olfactory nerves stimulates the hypothalums in the cortex of the brain which stimulates emotion

4-The pheromone scent triggers illcit emotions in the hypothalmus such as attraction , sexual desire and arousal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Smelly T-Shirt Studies

A

A series of studies has been conducted in which women have to sniff t-shirts
T-Shirts have been worn for several days by anonymous men
Women are asked to identify which ones smell (relatively) appealing

Some studies actually have the men run on treadmills and sweat a lot before collecting the T-shirts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Smelly T-Shirt Studies To produce the men’s most pure, untainted scents, during the study they aren’t allowed to:

A
wear deodorant or cologne
use scented soap
eat food that contains garlic, cumin or curry
smoke
drink alcohol
have sex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Smelly T-Shirt Studies Across these studies, a pattern emerges

A

Women prefer the body odor of men who have MHC variants that are mostly different from their own

When the researchers include a male relative among the men (father, brother), the women rate those t-shirts as the worst.
Why?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

MHC & Smell

A

Interestingly, men are far less sensitive to smells than are women
In fact, they are largely unable to detect MHC variants in odor

Unappealing MHC-related body odor is a deal-breaker for many women
Most guys are oblivious to it
Why?

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

MHC & Smell: Evolutionary Argument

A

Women appear attracted to the smell of men who only share few MHC variants

Human women aren’t alone in this preference
It’s well documented in birds, fish, and numerous other mammals

The bias appears to be about reproduction and species survival

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

MHC & Smell: Evolutionary Argument pt2

A

Reproductive success: Men

Getting women pregnant doesn’t cost men a lot

Men have the best chance of passing on their genes if they jump at every reproductive opportunity they get

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how does Major Histocompatibility Complex (MHC) work

A

MHC genes code for specific proteins that circulate in the blood stream

These proteins bind to odorants in concentrations that depend upon a person’s unique MHC

The odorants, in turn, ooze out of sweat glands in the armpits and genital areas

17
Q

If your partner has MHC variants similar to your own, your children might not be as healthy

A

Less varied MHCs identify and destroy a smaller range of bacteria and viruses

18
Q

What happens if you reproduce with someone whose MHC variants are mostly unlike your own?

A

Your kids may inherit a more diverse MHC variants
Leads to stronger immune systems
Identify and destroy a greater range of bacteria and viruses