Lecture 2: Human Population Growth Flashcards
(31 cards)
what is the approx world population?
just under 8 billion people
- expected to reach 8 by 2023 (according to UN) or 2026 according to US census
what are the top 3 largest countries by population?
- china
- india
- usa
Population=
individuals of the same species that co-occur in the same time and space
are humans considered one single population? why or why not?
Yes because we can travel/ disperse so easily
Populations grow/ shrink based on which 5 things?
- current size of the population
- birth rates
- death rates
*birth/ death rates= intrinsic rate of increase - immigration and emigration (not usually accounted for in models b/c they cancel each other out)
- carrying capacity (k)
define carrying capacity
the # of individuals of a particular species the local enviro can support
*when size of pop > k: pop growth will stop
what is the k value for humans?
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?
population density=
the # of individuals per unit area
population distribution/ dispersion=
give an example
the spatial arrangement of individuals within the population
- eg will cluster around water sources
what are the 3 types of population distribution?
give examples of each
- random
eg. dandelion and other plants that have wind-dispersed seeds that germinate wherever they happen to fall in favorable environments - regular/ even
- individuals are territorial- have a hierarchy
- spread out in a regular pattern
- eg penguins - Clumped
- mutual attraction between individuals, resources distributed in patches
- eg herd of elephants
Age distribution is affected by (4 factors)
-. periods of successful reproduction
- periods of low/ high juvenile & adult survival
- older individuals being replaced by younger?
- whether pop is declining
describe a stable population in terms of age structure
- 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)
describe an unstable population in terms of age structure
- absence of young individuals
- older not able to be replaced by young
- pop dominated by middle aged/ older individuals
___ ratio is a shaping factor of populations
sex ratio
- important b/c of mating
explain the curve in logistic population growth
- pop starts at a small size, and initially grows rapidly
- growth then starts to slow
- growth eventually stops, stabilizing at k
The less developed countries will account for __% of pop growth in the future
95%
where is the human pop growth rate highest (top 4 continents)
- asia
- africa
- europe
- north america
what was Thomas Malthus’ principle of population?
- 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
____ ____= human poop will grow too much and we will run out of food, causing chaos
malthusian catastrophe
are we in a Malthusian catastrophe yet?
globally, no
- maybe subnationally
- eg. Rwandan genocide- caused by lack of resources
catastrophism=
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)
neo-malthusianism=
start of the environmental movement of the 1970s
- assisting the poor (Malthus would disagree with this)
- inc efficiency (tractors)= more food
- birth control
What did the Malthusians do wrong?
give 3 examples
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
child mortality rate has ___ (inc/dec) over time
decreased
