Lecture 2: Human Population Growth

Question 1

what is the approx world population?

Answer 1

just under 8 billion people
- expected to reach 8 by 2023 (according to UN) or 2026 according to US census

Question 2

what are the top 3 largest countries by population?

Answer 2

1. china
2. india
3. usa

Question 3

Population=

Answer 3

individuals of the same species that co-occur in the same time and space

Question 4

are humans considered one single population? why or why not?

Answer 4

Yes because we can travel/ disperse so easily

Question 5

Populations grow/ shrink based on which 5 things?

Answer 5

1. current size of the population
2. birth rates
3. death rates
   *birth/ death rates= intrinsic rate of increase
4. immigration and emigration (not usually accounted for in models b/c they cancel each other out)
5. carrying capacity (k)

Question 6

define carrying capacity

Answer 6

the # of individuals of a particular species the local enviro can support

*when size of pop > k: pop growth will stop

Question 7

what is the k value for humans?

Answer 7

We don’t know!
- we are stretching k to the limit: our k is higher b/c of the technology we have developed
- as of right now, our k seems exponential, but we know it’s not- when will we reach it?

Question 8

population density=

Answer 8

the # of individuals per unit area

Question 9

population distribution/ dispersion=
give an example

Answer 9

the spatial arrangement of individuals within the population
- eg will cluster around water sources

Question 10

what are the 3 types of population distribution?
give examples of each

Answer 10

1. random
   eg. dandelion and other plants that have wind-dispersed seeds that germinate wherever they happen to fall in favorable environments
2. regular/ even
   - individuals are territorial- have a hierarchy
   - spread out in a regular pattern
   - eg penguins
3. Clumped
   - mutual attraction between individuals, resources distributed in patches
   - eg herd of elephants

Question 11

Age distribution is affected by (4 factors)

Answer 11

-. periods of successful reproduction
- periods of low/ high juvenile & adult survival
- older individuals being replaced by younger?
- whether pop is declining

Question 12

describe a stable population in terms of age structure

Answer 12

• more younger individuals than old (dominated by young)
• means that older individuals will be replaced by younger= stable
• graph is skewed to the left (more young)

Question 13

describe an unstable population in terms of age structure

Answer 13

• absence of young individuals
• older not able to be replaced by young
• pop dominated by middle aged/ older individuals

Question 14

___ ratio is a shaping factor of populations

Answer 14

sex ratio
- important b/c of mating

Question 15

explain the curve in logistic population growth

Answer 15

• pop starts at a small size, and initially grows rapidly
• growth then starts to slow
• growth eventually stops, stabilizing at k

Question 16

The less developed countries will account for __% of pop growth in the future

Answer 16

95%

Question 17

where is the human pop growth rate highest (top 4 continents)

Answer 17

1. asia
2. africa
3. europe
4. north america

Question 18

what was Thomas Malthus’ principle of population?

Answer 18

• if pop rates grow geometrically (double), but food abundance increases arithmetically, then humans will run out of food
• this will result in war, disease, and general chaos

Question 19

____ ____= human poop will grow too much and we will run out of food, causing chaos

Answer 19

malthusian catastrophe

Question 20

are we in a Malthusian catastrophe yet?

Answer 20

globally, no
- maybe subnationally
- eg. Rwandan genocide- caused by lack of resources

Question 21

catastrophism=

Answer 21

uncontrolled pop growth could lead to a pop crash due to :
- pandemic
- famine
- decline of k (if we deplete non-renewable resources etc)
- nuclear holocaust
- natural catasrophe (eg meteorite)

Question 22

neo-malthusianism=

Answer 22

start of the environmental movement of the 1970s
- assisting the poor (Malthus would disagree with this)
- inc efficiency (tractors)= more food
- birth control

Question 23

What did the Malthusians do wrong?
give 3 examples

Answer 23

considered humans as any other animal pop- didn’t consider culture, tech, etc
1. ireland famine- nobody did anything to help
2. experiments- sterilized ireland immigrants against their will, only the fittest allowed to reproduce
3. china- one-child policy

Question 24

child mortality rate has ___ (inc/dec) over time

Answer 24

decreased

Question 25

ecological footprint=

Answer 25

a tool used to express the enviro impact of an indiv or pop
- ie demand of the pop
- includes anything required to maintain your lifestyle (land occupied, water required to grow food, etc)

Question 26

biocapacity=

Answer 26

ability of the enviro to provide the resources we need to live
- ie supply from the enviro
- includes capacity to produce things we use AND absorb waste material geneterated by humans

Question 27

biocapacity > ecological footprint=

ecological footprint > biocapacity=

Answer 27

sustainable

unsustainable

Question 28

we’ve been living beyond the means of our planet since ___

Answer 28

1970

Question 29

the ___ ____ map measures the cumulative impact of direct pressures on nature from human activities, based on 8 inputs

Answer 29

human footprint map

1. built envrio extent
2. crop land
3. pasture land
4. human pop density
5. night-time lights
6. railways
7. roads
8. navigable waterways

Question 30

What are our 3 options to deal with uncontrolled pop growth?
Which should we actually use?

Answer 30

1. decrease births (humanely, with consent)
2. increase deaths (no)
3. have smaller footprints (best option)

Question 31

what are 3 ways we can produce better?

Answer 31

• dec inputs & waste in manufacturing/ production
• manage resources sustainably
• inc renewable energy production (more solar farms)