A Formica ant suspends a drop of aphid honeydew between her mandibles (which bristle with 7 or more teeth), as she drinks it. 
		Photo courtesy of Alex Wild, copyright, used with permission.WonderQuest:  On the web since 1997...      

Home   Top 10    Newsletter   Answer a question    Site Map   Fast answers 
Solving mysteries
WonderQuest

with April Holladay
New!  WeatherQuesting
 
Google
 
Web www.WonderQuest.com

     
RSS Add to Google

Answers About:  

   Animals
   Humans  
   Astronomy 
   Physics

Top 10 Questions

1. Ceiling fan - way to rotate

2. Average size US woman

3.  What animal lives longest?

4. Can eye color change?

5. Animals that mate for life

6. Does alcohol kill brain cells

7.Does the Moon rotate?

8. Septic tank - how often pump?

9. What exactly are hazel eyes?

10. Most poisonous animal!

 

Current Column: 

Petroglyphs from Bushmen of South Africa illustrating an early hunt with dogs. Picture used with permission from Pietermaritzberg: University of Natal Press.

Did humans and dogs become domesticated together?

There’s conjecture of how man and man’s best friend have influenced each other’s development


Here's your next question:


Why do birds sitting on a power line all face the same direction?

Deadline is 1 July. We will publish the best answers on 12 July.

Click here to give April your answer.

 

 

An (alleged) extra layer of female fat

Q: Do women really have an extra layer of fat that men don't? (Somewhere, USA)

Checking weight.   Courtesy of WikipediaA: That’s what I hear while shivering: "You shouldn’t be cold because you have an extra layer of fat under your skin."

My motive in answering this question is to drive a stake in the heart of an urban myth. I admit it. And, success is mine. At least, partly.

Checking weight. Courtesy of Wikipedia

"As a former anatomy professor, I can make this simple. . ." emails physiologist Jolie Bookspan, author of Health & Fitness in Plain English. "There is no extra layer in females."

"I checked the assumption about an extra layer of fat with our doc here. Neither of us is aware of an extra layer of subcutaneous fat," says physiologist Jolene H. Bodily of the Institute for Quality Health, the University of Virginia.

Take that, myth! No extra layer!

A cross section of human skin, showing the first layer called the epidermis (“E” in the diagram), the second layer (“D”) called the dermis.  The hypodermis, not actually part of the skin, lies immediately below the dermis, and contains the subcutaneous fat. Drawing from Safety Line Institute, State of Western Australia Government, and modified by the author.But then I got to thinking. What if my reader really means: is the fat layer thicker in women than men?  If true, then why do I get so cold?

Figure 2.  A cross section of human skin, showing the first layer called the epidermis ("E" in the diagram), the second layer ("D") called the dermis. The hypodermis, not actually part of the skin, lies immediately below the dermis, and contains the subcutaneous fat. Drawing from Safety Line Institute, State of Western Australia Government, and modified by the author.

Bodily goes on to say, "But women do carry more subcutaneous fat." See Figure 2.

"Women have slightly more subcutaneous fat than men," agrees exercise professor Len Kravitz of the University of New Mexico. "I have never seen a documented study quantifying how much more."

Furthermore, "Males and females are more alike than different," says Bookspan.

That’s what the experts say. My search of medical and biological journals turned up nothing.

Paul Ward of CoolAntarctica.com, however, touches on the central matter: "Subcutaneous fat has a part to play, of course, as an insulator, and women generally have more than men; so it helps them stay warm."

How much difference can a slightly-thicker fat layer make? Apparently, some: "Studies of cold water immersion report lower skin temperature in women than men," says Bookspan. Which figures if women feel colder than men.

But only the surface skin temperature is lower in females, not the deep-skin temperature. "Deep-skin temperatures remained higher compared to those of men under the same laboratory cold conditions (Malkinson, et al., 1981)."

Moreover, the advantage of women in the cold is not just due to fat, says Bookspan. In general, women also squeeze down blood vessels near the surface (vasoconstriction) to a greater extent than men do. Thus, blood flow near the skin is less in women and, therefore, blood temperature and deep-skin temperature is higher. So, when women have cold feet or hands it isn’t necessarily the result of poor circulation. "It's a healthy vasoconstrictive adaptation."

Considering the benefits, it’s OK, I guess, that women feel cold. Our bodies are just adapting to frigid conditions. We women will survive where our male counterparts might perish because of that slightly-thicker fat layer (and squeezed down blood vessels) if we ever encounter life-threatening cold.

Further Reading:

Many are cold but few are frozen by Jolie Bookspan, Dr.JolieBookspan.com

Health & Fitness in Plain English by Jolie Bookspan

Cellulite: Everything you want to know and more by Len Kravitz, "Ask Dr. Len Kravitz

The skin, SafetyLine Institute of Western Australia state government

The skin, Wikipedia

Malkinson, TJ, Martin S, Simper P, Cooper KE. Expired air volumes of males and females during cold water immersion. Can J. Physiol. & Pharmacol 1981; 59:843-846

How humans deal with and survive extreme cold by Paul Ward, CoolAntarctica.com

(Answered April 4, 2006)

 

Site Map

Question Archive WonderQuest's Features Info
Animals Sky   Contributors
Humans Art, TV, music   Ask a question About April --- what I do
Astronomy Food   Top 10 questions April's mountain and desert life
Mathematics Oceans & climate    April's 1000-mile paddle to the Arctic Ocean
Evolution & genetics Chemistry   Answer the question

  Newspapers with WonderQuest:

Earth Computers   Newsletter   Globe and Mail
Technology Microcreatures   More exploring -- good references   USA Today
Plants Physics   Fast answers   Happy News
Aerospace Home   Teachers' science corner Advertising

Copyright 2008 by April Holladay  

Please note: We use third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, or to opt out, click here: Google ad and content network privacy policy