Lecture 22 Unintended consequences - Health Flashcards
HEALTH & AGRICULTURE:
OSTEOLOGICAL EVIDENCE
Dental health: Increasing carbohydrates = increased caries (cavities)
Malnutrition & growth faltering: Dental defects;
reduced childhood growth rates, decrease in adult stature.
Demography: increasing birth rate, increase
population sizes
Infectious diseases: increase in chronic infectious like syphilis, TB, leprosy
Water quality/sanitation: increased parasites
NUTRITIONAL DEFICIENCIES
Reduced dietary breadth can result in malnutrition: diet in which one or more nutrients are either not enough or are too much such that the diet causes health problems.
Iron deficiency anemia – maize
* Increased carbohydrate; decreased protein
* Increased parasites load
NIACIN DEFICIENCY: PELLAGRA
Maize became staple in Europe in the 16-17C
Epidemics of niacin (vit B3) deficiency
4 Ds - dermatitis, diarrhea, dementia…. death
Pellagra absent in Mesoamerica
* Maize processed with addition of lime (calcium carbonate)
Increases bioavailability of niacin and tryptophan
Gene-culture coevolution:
genetic and cultural evolution act
in a continuous loop. Cultures create novel environments that
lead to new pressures from natural or social selection on genes.
AGRICULTURE & HUMAN EVOLUTION
1. Human self-domestication
Domestication syndrome in humans?
2. Genetic mutations associated with agricultural diets
Lactase Persistence; Carbohydrate metabolism
3. Genetic mutations associated with disease resistance
Tuberculosis & Urbanization
HUMAN SELF-DOMESTICATION?
Modern humans display suite of
domestication syndrome traits compared to Paleolithic ancestors (AMH and Neanderthals)
Decrease in cranial size, brain size,
mandible and tooth size, stature.
Associated with agriculture?
* Selection for decreased wariness and aggression with increased population sizes?
Linked to dietary changes?
LACTASE PERSISTENCE
** Lactase Persistence (LP):** the
continued activity of the enzyme
‘lactase’ in adulthood
Lactase helps digests the sugars
in milk (‘lactose’)
* ‘Lactose intolerance’ leads to
diarrhoea and flatulence
Most mammals stop producing
lactase after weaning – humans
are the exception
ADAPTATIONS TO AGRICULTURAL DIETS
Lactase persistence and cow milk production
* LP allele positive correlated with diversity of cattle milk protein diversity
Increased production of salivary amylase (Amy1) in populations with agricultural histories.
Also seen in domestic dogs
INFECTIOUS DISEASES
Low population densities in Paleolithic
* 25-50 person H-G groups, 0.1-0.2/mile2
Increasing density in Neolithic:
* Sedentism; city states 3000 BC – endemic diseases
* New disease vectors: domestic animals; mosquitos (malaria)
Infectious disease resistance genes
* Selection for allele associated with natural resistance to intracellular pathogens like TB and leprosy (SLC11A1 1729 + 55del4) in populations with long history of
urbanization
AGRICULTURE & ZOONOSES
**Zoonoses: **pathogen which can be transmitted to humans from animals (bacteria, viruses, parasites)
TB, measles & whooping cough can be transferred between humans and
domestic animals
aDNA reveals plague and typhoid fever have their roots in the Neolithic
RINDERPEST (CATTLE PLAGUE)
Viral infection (Morbillivirus) affecting cattle, buffalo, and wild ungulates.
Originated in Asia, spreading to Egypt in 3000BC
Rest of Africa with European colonization
Massive outbreaks in Europe, 18C
80-90% mortality of African cattle in 1890s
Loss of plow animals, herds, hunting →Mass starvation
Grassland thickets → tsetse fly breeding grounds
Eradicated through inoculation in 2001
But now, canine distemper (also a Morbillivirus)
PHYTONOSES: DISEASES
TRANSMITTED FROM PLANTS
Bacterial communities from
different habitats,
- from cattle intestinal track
system via manure - surface water via irrigation,
- and from soil and plants, all
coming together at plant growth in
arable production systems.
GLOBALIZATION
AND THE SPREAD
OF DISEASE
cOLUMBIAN EXCHANGE &
ZOONOSES
Widespread transfer of
plants, animals,
technology, diseases,
and ideas between the
New World (Americas)
and the Old World
(Africa, Asia, Europe) in
the 15th and 16th
centuries
EPIDEMIC PATHOGENS
Introduction of smallpox, measles,
chickenpox, influenza, typhus, typhoid
diphtheria, cholera, scarlet fever,
whooping cough, malaria…
Devastating effect on ‘virgin’ populations of the New World
80–95% mortality within 100–150 yrs
Waves of disease spread in advance of Spanish colonists
DETECTING OLD WORLD
PATHOGENS
Historical and archaeological evidence for an epidemic that decimated Mexican populations in
1545-1550 (Huey Cocoliztli - Great Pestilence’ in Nahautl)
Symptoms: red spots on the skin, bleeding from various body orifices, vomiting
Ancient DNA analysis of skeletons from a cemetery at Teposcolula-Yucundaa, Oaxaca in southern
Mexico
Pathogen identified as Salmonella enterica ParatyphiC (paratyphoid fever
MEDIEVAL
AGRICULTURE
Common fields, little private ownership, tenant farming
Open field cultivation – same crops grown repeatedly
Crop rotation: 1 in 3 field
fallow (“plough sick”)
Few livestock: no winter
fodder, little manure for soil fertility
THE (2ND) AGRICULTURAL REVOLUTION
15th to 19th C (especially 1760-1840)
Change in land-tenure system
Increased crop yield
Improvement in livestock
Human population growth, increasing urbanization
Labour for Industrial revolution
ADVANCES IN BRITISH
AGRICULTURE
- Enclosure of common fields: Private ownership, large scale farming
- 4-course crop rotation: (turnips, barley, clover, wheat); animal fodder; soil fertility, reduced weeds
- New crops: Maize, potatoes for fodder
- New technologies: Jethro Tull horse-drawn seed-drill; greater mechanization
- Improved livestock: Larger cattle, pigs, sheep; distinctive local breeds; manure
