Laura Vaughan

0129064

HEART ATTACKS:

A MISMATCH BETWEEN OUR DESIGN AND OUR ENVIRONMENT    

Word Count 700

A heart attack is the death or injury of part of the heart muscle due to a sudden loss of blood supply (Anonymous 2003).  Approximately there are 75 000 heart attacks in Canada each year and of those, 24 000 result in death (Statistic Canada 1998).  Heart attacks however have only become a widespread problem in this century and to this day remain rare among hunter-gathers (Anonymous 1999). 

  From a Darwinian perspective this is very interesting because heart attacks result mainly from artherosclerosis and artherosclerosis results mainly from high intakes of fat (Anonymous 1999).  More than 30 percent of Canadians daily diet consists of fat, even though we know it is unhealthy (Anonymous 2002).  In past centuries fat resources were very scarce but those individuals who consumed fat when given the rare opportunity had a selective advantage over their leaner companions when famines occurred (Anonymous 1999). We as their descendants still carry those urges for fat (Anonymous 1999) and perhaps then there is a reason why many continue to make such unhealthy food choices that lead to heart attacks.

  Symptoms:

• Chest discomfort
• Discomfort in other areas of the upper body
• Shortness of breath

Further Information

(National Heart, Lung, and Blood Institute 2004)

Proximate Causes:

A heart attack occurs when an area of the heart is deprived of a necessary supply of blood, causing that part of the heart to be injured or die (Anonymous 2003).  Typically the loss of blood is caused by a complete blockage of a coronary artery by a blood clot (Anonymous 2003). Such blood clot is formed by cholesterol plaque, which is a thick substance within the artery walls (Anonymous 2003).  The accumulation of cholesterol plaque causes thickening of the artery walls and narrowing of the arteries; a process called artherosclerosis (Anonymous 2003).  A high fat diet and genes that predispose one to atherosclerosis can accelerate artherosclerosis and are the major proximate causes of heart attacks (Nesse & Williams 1996).

Evolutionary Causes: 

“Novel environments” is the most relevant evolutionary cause of heart attacks.  The human design occurred centuries ago on the African savanna, where humans were hunter-gatherers and ate mostly lean meats and foods high in starch (Neese & Williams 1996). At that time, fat, salt, and sugar were scarce and precious resources and individuals who had a craving to consume large amounts of such resources when given the rare opportunity had a selective advantage over their more lean companions when famines occurred (Neese & Williams 1996).  Having such a craving was beneficial to hunter-gatherers because it caused them to seek out the scarce resources, which were essential to their survival  (Neese & Williams 1996).  

We are the descendants of these well-adapted individuals and we retain their fondness for fat, salt, and sugar (Neese & Williams 1996).  However, in our environment where these resources are available in abundance, there is a mismatch between our design and our environment (Neese & Williams 1996). Such mismatch has resulted in heart attacks caused by atherosclerosis due mainly by our tendencies to over consume such resources (Neese & Williams 1996).  Although we know that we should limit our fat intake, our evolved tendencies tend to subvert our intellects because our brains are shaped to cope with an environment substantially different from the one we now inhibit (Anonymous 1999).  Natural selection has yet revised our bodies for coping with fatty diets and therefore eating healthy does not come naturally and heart attacks have become a widespread problem in this century (Neese & Williams 1996). 

Current treatments: 

• Thrombolytic Therapy
• Heparin Therapy
• Aspirin
• Beta-Blockers
• Nitro-glycerine
• IIb/IIIa Inhibitors
• Primary PTCA
• Calcium-channel blockers
• Nicorandil
• Diuretics
• Cholesterol-reducing medicines

(Anonymous 2003)

 Current treatments simply aid the proximate, not the evolutionary causes of heart attacks and thus, treatments should change and account for the evolutionary causes of heart attacks.  Instead of treating heart attacks after the fact or symptoms, treatments should focus on how to eliminate or/and control fat cravings.  If we could eliminate and control our craving to eat fat, we could then perhaps eliminate the high incidence of artheroscelorsis, moreover heart attacks. 

 References

 Anonymous. 2003.  Heart: health and medical information. [online]. Available from:

    http://www.medicinenet.com/Heart_Attack/page1.htm> Accessed 2004 Feb 11.  

 Anonymous.  2002.  Canada-US dietary reference intakes. [online]. Available from:

    < http://www.sugar.ca/artMacroNutrients1Prt.htm> Accessed 2004 Feb 11.  

 Anonymous. 1999. Darwinian medicine. [online]. Available from:

    <http://clawww.lmu.edu/faculty/tshanahan/DarMed.html> Accessed 2004 Feb 11. 

 National Heart, Lung, and Blood Institute.  2004. Heart attack.  [online]. Available from:             <http://dci.nhlbi.nih.gov/Diseases/HeartAttack/HeartAttack_SignsAndSymptoms.html> Accessed 2004 Feb 11. 

 Neese RM. Williams GC.  1996.  Why we get sick.  New York: Vintage Books.  290 p. 

 Stats Canada. 1998.  Current and future hospitalization after heart attack. [online].  Available from:

    <http://www.statcan.ca/english/indepth/82-003/feature/hrab1998010002s3a02.htm6.>  Accessed 2004 Feb 11.