Download Evolutionary Medicine www.AssignmentPoint.com Evolutionary

Evolutionary Medicine
www.AssignmentPoint.com
www.AssignmentPoint.com
Evolutionary medicine or Darwinian medicine is the application of modern
evolutionary theory to understanding health and disease. The goal of
evolutionary medicine is to understand why people get sick, not simply how
they get sick. Modern medical research and practice has focused on the
molecular and physiological mechanisms underlying health and disease, while
evolutionary medicine focuses on the question of why evolution has shaped
these mechanisms in ways that may leave us susceptible to disease. The
evolutionary approach has driven important advances in our understanding of
cancer, autoimmune disease and anatomy. Medical schools have been slower to
integrate evolutionary approaches because of limitations on what can be added
to existing medical curricula.
Human adaptations
Adaptation works within constraints, makes compromises and tradeoffs, and
occurs in the context of different forms of competition.
Constraints
Adaptations can only occur if they are evolvable. Some adaptations which
would prevent ill health are therefore not possible.
DNA cannot be totally prevented from undergoing somatic replication
corruption; this has meant that cancer, which is caused by somatic mutations,
has not (so far) been completely eliminated by natural selection.
Humans cannot biosynthesize Vitamin C, and so risk scurvy, Vitamin C
deficiency disease, if dietary intake of the vitamin is insufficient.
www.AssignmentPoint.com
Retinal neurons and their axon output have evolved to be inside the layer of
retinal pigment cells. This creates a constraint on the evolution of the visual
system such that the optic nerve is forced to exit the retina through a point
called the optic disc. This in turn creates a blind spot. More importantly, it
makes vision vulnerable to increased pressure within the eye (glaucoma) since
this cups and damages the optic nerve at this point, resulting in impaired vision.
Other constraints occur as the byproduct of adaptive innovations.
“Diseases of civilization”
Humans evolved to live as simple hunter-gatherers in small tribal bands, a very
different way of life and environment compared to that faced by contemporary
humans. This change makes present humans vulnerable to a number of health
problems, termed “diseases of civilization” and “diseases of affluence”. Humans
were designed to live off of the land, and take advantage of the resources that
were readily available to them. They were designed for the stone-age, and the
environments of today bring about many disease causing ailments, that may or
may not be deadly. “Modern environments may cause many diseases-for
example, deficiency syndromes such as scurvy and rickets”.
Diet
In contrast to the diet of early hunter-gatherers, the modern Western diet often
contains high quantities of fat, salt, and simple carbohydrates, which include
refined sugars and flours. These create health problems.
 Trans fat health risks
 Dental caries
www.AssignmentPoint.com
 High GI foods
Modern diet based on "common wisdom" regarding diets in the paleolithic era
Life expectancy
Examples of aging-associated diseases are atherosclerosis and cardiovascular
disease, cancer, arthritis, cataracts, osteoporosis, type 2 diabetes, hypertension
and Alzheimer's disease. The incidence of all of these diseases increases rapidly
with aging (increases exponentially with age, in the case of cancer).
Of the roughly 150,000 people who die each day across the globe, about two
thirds—100,000 per day—die of age-related causes. In industrialized nations,
the proportion is much higher, reaching 90%.
Exercise
Many contemporary humans engage in little physical exercise compared to the
physically active lifestyles ancestral hunter-gatherers. It has been proposed that
since prolonged periods of inactivity would have only occurred in early humans
following illness or injury that it provides a cue for the body to engage in lifepreserving metabolic and stress related responses such as inflammation that are
now the cause of many chronic diseases.
Cleanliness
Contemporary humans - due to medical treatment, frequent washing of clothing
and the body, and improved sanitation - are mostly free of parasites, particularly
intestinal ones. This causes problems in the proper development of the immune
www.AssignmentPoint.com
system although hygiene can be very important when it comes to maintaining
good health. The hygiene hypothesis says that many modern humans are not
exposed to microorganisms that have evolved in establishing the immune
system as they should be. “Microorganisms and macroorganisms such as
helminths from mud, animals, and feces play a critical role in driving
immunoregulation’. They play a crucial role in building and training immune
functions to fight off and repel some diseases, and protect against excessive
inflammation which has been implicated in several diseases (such as recent
evidence for Alzheimer's Disease).
www.AssignmentPoint.com