Evolution and disease

Question 1

What is evolutionary knowledge allowing us to understand about human disease?

Answer 1

The evolution of pathogens, the genetic basis to disease susceptibility and the understanding of disease by comparing our genome to other species.

Question 2

What are 6 evolutionary explanations for why humans are vulnerable to disease?

Answer 2

Pathogens evolve faster than their hosts, natural selection lags behind environmental change, trade-offs make it nearly impossible for natural selection to solve certain biological problems, evolutionary history puts constraints on changes natural selection can bring about, some traits increase reproductive fitness a the cost of causing disease, and what may appear to be disease may be adaptation.

Question 3

Why, despite our sophisticated immune system and drugs, do infectious diseases cause so many deaths each year?

Answer 3

Pathogens adapt to overcome our immune system and drugs.

Question 4

What is virulence?

Answer 4

The harm a pathogen does, which is usually a result of the use of resources by the pathogen.

Question 5

What is transmission?

Answer 5

The ease with which a pathogen infects other individuals.

Question 6

What features allow pathogens to have the potential for rapid evolution?

Answer 6

They have ahigh mutation rate and DNA transfer between bacteria, along with a high reproduction rate.

Question 7

How can public health practices influence pathogen virulence?

Answer 7

Make transmission harder or lead to lower or high virulence.

Question 8

Why does antibiotic resistance evolve rapidly?

Answer 8

Bacteria can acquire mutations through vertical and horizontal transfer. Antibiotics provide a strong selective pressure.

Question 9

How can the sickle cell allele be useful?

Answer 9

It provides protection against malaria, but causes sickle cell anaemia if inherited from both parents.

Question 10

What are genetic disorders?

Answer 10

Disorders where the genotype of an individual has a strong effect over whether an individual will be affected.

Question 11

How can the chances of genetic disorders be increased?

Answer 11

When a population is founded by a small number of individuals, or when related individuals have offspring (inbreeding).

Question 12

How can understanding the role of genetic variation in disease be useful?

Answer 12

Lead to better treatments and can help predict drug reactions.

Question 13

What are proto-oncogenes?

Answer 13

Normal genes that can cause cancer when they acquire certain mutations.

Question 14

What are oncogenes?

Answer 14

Mutated versions of proto-oncogenes.

Question 15

How does cancer occur?

Answer 15

When cells divide uncontrollably.

Question 16

What diseases related to lifestyle are now causing death?

Answer 16

Diseases related to lack of exercise, alcohol consumption, bad diet etc.

Question 17

What is the hygiene hypothesis?

Answer 17

The idea that the reduction in exposure to pathogens and bacteria can explain the increase in autoimmune diseases such as asthma. It is the idea that our world is too sterilised, causing our immune system to over react.

Question 18

What are the hypotheses for susceptibility for type II diabetes?

Answer 18

The thrifty genotype, thrifty phenotype and thrifty epigenotype.

Question 19

What is the thrifty genotype?

Answer 19

The idea that genotypes advantageous in the past are now detrimental due to access to calorie-rich foods.

Question 20

What is the thrifty phenotype hypothesis?

Answer 20

The idea that a nutrient-poor fetal environment can alter lifetime physiology.

Question 21

What is the thrifty epigenotype hypothesis?

Answer 21

The idea that epigenetic mechanisms couple fetal nutrition with particular physiology.