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Prevention of Refractive Defects of Vision by Means of Evolutionary Medicine
Libertini G. (M.D., Independent Researcher)
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Evolutionary Medicine is not an Alternative Medicine (like
homeopathy, iridology, ayurvedic medicine, naturopathy,
traditional Chinese medicine, energy medicine, etc.)
but
a Medicine that is more thoroughly scientific
in that it involves the concepts of Evolutionism.
What is Evolutionary Medicine?
Evolutionary or Darwinian Medicine [1-6] comes into being in
1991 [1], but there are some known forerunners [7] (e.g. [8]) and
others not generally cited as forerunners [9,10].
A medicine that ignored
the principles of chemistry,
for example, would be
partially scientific.
[1] Williams GC, Nesse RM (1991) The dawn of Darwinian medicine. Quart. Rev.
Biol. 66, 1-22.
[2] Nesse RM, Williams GC (1994) Why we get sick. New York (USA), Times
Books.
[3] Stearns SC (ed) (1999) Evolution in health and disease (1st ed.). Oxford (UK),
Oxford University Press.
[4] Trevathan WR, Smith EO, McKenna JJ (eds) (1999) Evolutionary Medicine.
New York (USA), Oxford University Press.
[5] Trevathan WR, Smith EO, McKenna JJ (eds) (2008) Evolutionary Medicine:
new perspectives. New York (USA), Oxford University Press.
[6] Stearns SC, Koella JC (eds) (2008) Evolution in health and disease (2nd ed.).
Oxford (UK), Oxford University Press.
[7] Trevathan WR, Smith EO, McKenna JJ (2008) Introduction and overview of
Evolutionary Medicine. In: Trevathan WR, Smith EO, McKenna JJ (eds)
Evolutionary Medicine: new perspectives. New York (USA), Oxford University
Press.
[8] Eaton SB, Shostak M, Konner M (1988) The paleolithic prescription: a program
of diet & exercise and a design for living. New York (USA), Harper & Row.
[9] Price WA (1939) Nutrition and Physical Degeneration. New York – London,
Paul B. Hoeber.
[10] Libertini G (1983) Ragionamenti Evoluzionistici. Naples (Italy), Società
Editrice Napoletana; English Edition (2011): Evolutionary Arguments, Crownsville
(USA), Azinet Press.
Similarly, a medicine that ignores
the principles of evolution
is partially scientific.
Is this difference only a theoretical / verbal nicety?
or
Does this difference have strong and significant implications for
the structure of medical studies and for health organization?
Refractive defects (myopia, astigmatism and hyperopia) are a
group of related diseases with frequency:
- very common [1-3]
- varying greatly from population to population (e.g.: “The
prevalence of myopia in Asia is as high as 70-90%, in Europe
and America 30-40%, and in Africa 10-20 %” [1])
…
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Data from Step 1 and Step 2 indicate that refractive defects are
surely a group of diseases caused by environmental factors, i.e.
by presumable mismatch phenomena.
[1] Cordain, L, Eaton, SB, Miller, JB, Lindeberg, S, Jensen, C (2002)
An evolutionary analysis of the aetiology and pathogenesis of juvenileonset myopia. Acta Ophthalmol. Scand. 80, 125–35.
The study of primitive peoples shows that these defects are very
rare or nonexistent among them.
As regards Australian Aborigenes: “The marvelous vision of
these primitive people is illustrated by the fact that they can see
many stars that our race cannot see. In this connection it is
authoritatively recorded regarding the Maori of New Zealand
that they can see the satellites of Jupiter which are only visible
to the white man's eye with the aid of telescopes. These people
prove that they can see the satellites by telling the man at the
telescope when the eclipse of one of the stars occurs. It is said of
these primitive Aborigines of Australia that they can see
animals moving at a distance of a mile which ordinary white
people can not see at all.” [1]
As regards Yakuts (a Siberian people): “Many travelers
observed what some of them call ‘telescopic’ eyesight among
these peoples. A Yakut distinguished with the naked eye stars in
the Pleiades not usually seen without a telescope. The Yakuts
say there are many stars in this group, but only seven large
ones” [2]
…
[1] Rose KA , Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw S-M
(2008) Myopia, lifestyle, and schooling in students of Chinese ethnicity
in Singapore and Sydney. Arch. Ophthalmol. 126, 527-30.
[2] Cordain, L, Eaton, SB, Miller, JB, Lindeberg, S, Jensen, C (2002)
An evolutionary analysis of the aetiology and pathogenesis of juvenileonset myopia. Acta Ophthalmol. Scand. 80, 125–35.
[3] Garner LF, Owens H, Kinnear RF, Frith MJ. (1999) Prevalence of
myopia in Sherpa and Tibetan children in Nepal. Optom. Vis. Sci. 76,
282-5.
[4] Edwards MH, Lam CS (2004). The epidemiology of myopia in
Hong Kong. Ann. Acad. Med. Singapore. 33, 34-8.
[5] Morgan, RW, Munro, M (1973) Refractive problems in northern
natives. Can. J. Ophthalmol. 8,: 226–8.
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“a number of lines of evidence strongly reject the notion that
[a] recent (in evolutionary terms) relaxation of natural
selection pressures could be responsible for the high incidence
of myopia in modern, technological societies.” [1]
Step 2 - Comparison between the frequency of a disease in
modern populations and the frequency of the same
disease in populations in primitive conditions
(From [2]:) Figure 1.
Moderate myopia (1.00–
5.00 D) by age in Indians
and Eskimos of the
Yukon and NorthWest
territories. Adapted from
Morgan & Munro (1973)
([5])
[1] Fredrick DR (2002) Myopia. BMJ. 324, 1195-9.
[2] Dirani M et al. (2010) Prevalence of refractive error in
Singaporean Chinese children: the strabismus, amblyopia, and
refractive error in young Singaporean Children (STARS) study.
Invest. Ophthalmol. Vis. Sci. 51, 1348-55.
[3] Chow YC, Dhillon B, Chew PT, Chew SJ (1990) Refractive errors
in Singapore medical students. Singapore Med. J. 31, 472–3.
…
As regards two hunter-gatherer populations:
“Using a retinoscope and cycloplegia, Holm (1937) refracted
2364 members (aged 20–65 years) of several hunter-gatherer
tribes in Gabon (formerly French Equatorial Africa) in 1936.
Of the 3624 eyes examined, only 14 were classified as myopic
(nine eyes from − 0.50 to 1.00 D; five eyes from − 3.00 to − 9.00
D), thereby yielding a myopia incidence rate of 0.4%. Similar
low rates for myopia were reported by Skeller (1954), who
refracted the eyes of 775 Angmagssalik Eskimos as part of a
comprehensive anthropological study carried out in 1954.
Retinoscopy in conjunction with cycloplegia demonstrated that
of the 1123 eyes examined, only 13 (1.2%) were classified as
myopic (nine eyes =− 1.00 D; four eyes =− 1.25 D).” [1]
[1] Eaton SB, Shostak M, Konner
M
(1988)
The
paleolithic
prescription: a program of diet &
exercise and a design for living.
New York (USA), Harper & Row.
[2] Libertini G (2009) Prospects of
a Longer Life Span beyond the
Beneficial Effects of a Healthy
Lifestyle, in: Bentely JV, Keller
MA (eds) Handbook on Longevity:
Genetics, Diet & Disease, New
York (USA), Nova Science
Publishers Inc.
…
- varying greatly within the same population with changing
conditions [1-3]
- varying greatly within a population over a short time [2,4,5]
(see Figure)
Step 1 - Epidemiological study
of modern populations
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Here, I develop a practical
application of a simple concept,
the “mismatch” [1,2], to the
genesis of refractive defects of
vision.
If a species is adapted to a certain range of conditions (including
diet, environmental conditions, interrelations with other living
beings, etc.), called for brevity “ecological niche”, any change in
the ecological niche potentially is a source of disfunctions
(diseases), because there is no adaptation to the new conditions.
This is defined as "mismatch”.
So, the contrast is not between
current medicine and
alternative medicines
but
between current medicine (which in
most cases ignores Evolutionism)
and Evolutionary Medicine
(which is a more thoroughly
scientific medicine)
Refractive Defects of Vision
in the Context of Evolutionary Medicine
Evolutionary Medicine involves
many concepts and applicative
consequences.
The concept of “mismatch” is simple but with huge implications:
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[1] Price, WA (1939) Nutrition and Physical Degeneration. New York –
London, Paul B. Hoeber.
[2] De Hutorowicz H, Adler BF (1911) Maps of Primitive Peoples. Bull.
Amer. Geogr. Soc. 43, 669-79.
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Step 3 - Hypotheses on the possible changes in the
ecological niche underlying the disease
and on possible pathogenetical mechanisms
Excessive near work, especially using artificial lighting, an
improbable condition in the ecological niche to which we are
adapted, is a common hypothesis regarding the causes of
refractive defects, in particular myopia [1,2].
Against this hypothesis: “In an earlier study of 977 school
children (6–17 years of age) on the remote South Pacific island
of Vanuatu, Garner et al. (1985) found that only 1.3% of
subjects had myopia greater than − 0.25 D, despite engaging in
about 8 hrs of school work per day.” [3]
Another hypothesis ascribes the epidemic of myopia incidence
to dietary alterations, in particular the “increase in high
glycaemicload foods” [3]. But, in two homogeneous populations
with no detectable difference in dietary habits, incidence of
myopia was very different [4].
…
[1] Zylbermann R, Landau D, Berson D (1993): The influence of study
habits on myopia in Jewish teenagers. J. Pediatr. Ophthalmol.
Strabismus 30, 319–22.
[2] McBrien NA, Adams DW (1997): A longitudinal investigation of
adult-onset and adult-progression of myopia in an occupational group.
Refractive and biometric findings. Invest Ophthalmol. 38, 321–33.
[3] Cordain L, Eaton SB, Miller JB, Lindeberg S, Jensen C (2002) An
evolutionary analysis of the aetiology and pathogenesis of juvenileonset myopia. Acta Ophthalmol. Scand. 80, 125–35.
[4] Rose KA , Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw S-M
(2008) Myopia, lifestyle, and schooling in students of Chinese ethnicity
in Singapore and Sydney. Arch. Ophthalmol. 126, 527-30.
…
A study was made of two homogeneous groups of 6-7-years old
children of Chinese ethnicity, living in Singapore and in Sidney,
respectively, with the same frequency of myopia in their
parents: “Children in Sidney read more books per week (P <
.001) and did more near-work activity (P = .002). Children in
Sidney spent more time on outdoor activities (13.75 vs 3.05
hours per week) (P < .001)”. The prevalence of myopia was
3.3% in Sidney and 29.1% in Singapore [1].
This suggests that the critical factor is the outdoor activity, alias
the exposition to natural light, a hypothesis confirmed by other
studies [2,3].
In particular “Higher levels of total time spent outdoors, rather
than sport per se, were associated with less myopia” [2].
In these studies, near-work activities appeared to be an
independent aggravating factor, but not the main cause of
myopia [2,3].
[1] Rose KA, Morgan IG, Smith W, Burlutsky G, Mitchell P, Saw SM
(2008) Myopia, lifestyle, and schooling in students of Chinese ethnicity
in Singapore and Sydney. Arch. Ophthalmol. 126, 527-30.
[2] Rose KA, Morgan IG, Ip J, Kifley A, Huynh S, Smith W, Mitchell
P. (2008) Outdoor activity reduces the prevalence of myopia in
children. Ophthalmol. 115, 1279-85.
[3] Dirani M, Tong L, Gazzard G, Zhang X, Chia A, Young TL, Rose
KA, Mitchell P, Saw SM. (2009) Outdoor activity and myopia in
Singapore teenage children. Br. J. Ophthalmol. 93, 997-1000.