ANHB1102 Lecture Notes - Lecture 30: Dental Caries, Wisdom Tooth, Estrogen
25 May 2018
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Evolution and Disease Notes:
Evolution: genetic change in a population over time, resulting from the four forces of evolution
Natural Selection:
-Phenotypic variation exists among individuals
-Variati9on is heritable
-Individuals with heritable traits better suited to the environment will survive better and reproduce
more offspring (higher fitness)
-Alleles in those individuals with higher fitness tend to become more common in the population in
subsequent generations
Evolution by Natural Selection:
-Natural selection work through differential reproduction - traits selected for may be ‘better’ but
not the ‘best
How we adapt to the environment:
-Survive and reproduce
-Food, water, shelter and mates - our success at doing this measured by fitness
-Environment makes this hard to achieve - hostile and changeable
Types of Adaptations:
-Features or rats that help the organism (and ultimately the population) cope better with the
challenges in the environment
1. Genetic
-Species wide
-Population specific
-Acclimatisations/Acclimations
2. Cultural
-Cultural adaptations are possible because we have the appropriate genetic adaptations
Human Evolution and the Modern Human Anatomy:
-Today - strongest force of selection in humans is:
-Gene-cultural interaction
-Many medical procedures allow better survival and affect differential reproductive success
When our Adaptations fail us - why we get sick:
-Many diseases that affect us today are the consequences of our evolutionary past
-But…Natural selection has no plan and can only ‘use’ the genetic material that is avaliable
Endurance Walking and Running:
-We have evolved to walk and run distances
-Our long term health depends on this requirement for exercise
-Supportive shoes? our feet and vertebral columns are equipped with arches, ligaments and
tendons
-Many mismatch diseases result from a modern lifestyle which relies on transport and sitting
down for long periods
Digestive System:
-Our digestive anatomy and physiology - a strongly herbivorous past
-Can utilise a wide range of plant foods - supplemented with opportunistic meat eating
-Capturing and eating animal prey = energetically costly for primates
-However, even the earliest human technology has reduced energy cost - culturally buffered
Hunter-Gather Background:
-The human body is selected to cope with a patchy, unpredictable environment
-We are selected for daily exercise - endurance running
-Our bodies are adapted for relative ‘feast and famine’
-The hunter-gatherer diet is variable - protein, carbohydrate and fat from unprocessed sources
The adoption of agriculture and farming:
-A greater reliance on carbohydrates - poorer sources of food
-Plentiful supplies…but greater risk of famine
-Higher concentrations of people - disease reservoir
-Harder work to bring in poorer quality diet
-Greater political pressures and social stress
-BUT - higher reproductive rates (labor force)
The appearance of ‘new’ diseases:
-Greater population in settled farming communities:
-Provides a reservoir for many infectious diseases
-Bacteria thrives in unsanitary conditions (unable to rid waste)
-Carbohydrate-rich diet involves several new conditions
The Industrial Age:
-Early industrialisation - the problems of overcrowding
-Travel spreads infections from one reservoir to the next
-The list is long…
-Bubonic plague
-Smallpox
-Cholera
-Influenza
The good news and the bad news:
-Our bodies are largely the same as the pas t thousands of years but cultural change has been
rapid in the past 150 years
Teeth - modern dental problems:
-Orthognathic faces and ‘vestigial’ wisdom teeth?
-Modern diets and dental caries and gum diseases
Ancient Diseases - more prevalent now?
e.g Crohn’s Disease and Psoriasis
-DNA deletions in common ancestor of Neanderthals, Denisovans and modern humans
-Both autoimmune diseases
-In a pathogen-rich environment, could this response have been beneficial
-Made moderns humans much more seseptible - antibiotics
-Cancers:
-The great majority of cancers are due to environmental factors - lifestyle, economic and
behavioural
-Only 5-10% are genetic
-Tobacco (25-30%), Diet and Obesity (30-35%), Infections (15-20%), Radiation (up to 10%)
-Stress, lack of physical activity, environmental pollutants
-Our longer lives mean that more of us will develop cancers
Good News
Bad News
Living longer and healthier
Heavier
Soap, sanitation and vaccination, antibiotics
Sleep less
Taller
Cancers - the nun’s disease:
-Breast, ovarian and uterine cancers
-Women without children = more menstrual cycles - higher rates
-More oestrogen (and other reproductive hormones) cause cells of uterus and breast to
proliferate and divide
-Risk of mutant cells with proliferation
-More children and longer breast feeding -lowers exposure to repeated high doses of
oestrogen
Sleep loss in younger people since 1910:
Loss of Sleep:
-Impaired judgement
-Diminished creativity
-Inability to concentrate
-Reduced language and communication skills
-Slowed reaction times
-Decreased ability to learn and remember
-20% increase in physical problems
-Encourages weight gain
Sleep and Modern Life:
-Artificial light presents sleep-promoting neurons in the brain
-Reduces the nightly release of melatonin
-Short blue wavelength light is especially harmful to circadian rhythms
-Blue light surpasses malting more vigorously than other light wavelengths
-Computers and artificial light bulbs
The modern ‘Western diet’:
-Obesity Epidemic:
-Calories in versus calories out
-Processed vs ‘natural’ foods
Humans: fat, sweaty and coat?
-Fat:
-Newborns - 15% humans 3% chips
-10-20% in human males
-24-31% in human females
-Good longer-term source of energy for hunter-gatherers
-Women’s fertility drops with fewer fat reserves
Document Summary
Evolution: genetic change in a population over time, resulting from the four forces of evolution. Individuals with heritable traits better suited to the environment will survive better and reproduce more offspring (higher tness) Alleles in those individuals with higher tness tend to become more common in the population in subsequent generations. Natural selection work through differential reproduction - traits selected for may be better" but not the best. Food, water, shelter and mates - our success at doing this measured by tness. Environment makes this hard to achieve - hostile and changeable. Features or rats that help the organism (and ultimately the population) cope better with the challenges in the environment: genetic. Cultural adaptations are possible because we have the appropriate genetic adaptations. Today - strongest force of selection in humans is: Many medical procedures allow better survival and affect differential reproductive success. When our adaptations fail us - why we get sick:
