Lesson 2 Flashcards
(53 cards)
In human biology, this is the whole number of inhabitants occupying an area (such as a country or the world) and continually being modified by increases (births and immigrations) and losses (deaths and emigrations.
Population
The size of a human population is limited by the:
(1) supply of food
(2)the effect of diseases
(3)other environmental factors.
Human populations are further affected by _______, especially in medicine and public health that have reduced mortality and extended the life span.
(1)social customs governing reproduction
(2) the technological developments
Demographers distinguish between _____, the underlying biological potential for reproduction, and fertility, the actual level of achieved reproduction.
Fecundity
The difference between biological potential and realized fertility is determined by several intervening factors, including the following:
(1) most women do not begin reproducing immediately upon the onset of puberty, whick itself does not occur at a fixed age;
(2) some women with the potential to rèproduce never do so;
(3) some women become widowed and do not remarry;
(4) various elements of social behavior restrain fertility;
(5) and many human couples choose consciously to restrict their fertility by means of sexual abstinence, contraception, abortion, or sterilization.
It is the increase in the number of individuals in a population.
Population growth
Global human population growth amounts to around—
83 million annually, or 1.1% per year.
The global population has grown from—
I billion in 1800 to 7.6 billion in 2017.
It is expected to kcep growing, and estimates have put the total population at—(3)
(1) 8.6 billion by mid-2030
(2) 9.8 billion by mid-2050
(3) and 11.2 billion by 2100.
Many nations with rapid population growth have—
Low standards of living
Many nations with low rates of population growth have—
High standards of living.
Population began growing rapidly in the Western world carly in the—
Industrial revolution of the late 18th century.
The reasons for the “Modern Rise of Population” were particularly investigated by this British health scientist.
Thomas McKeown (1912-1988).
McKeown challenged four theories about the population growth: (4)
(1) McKeown stated that the growth in Western population, particularly surging in the 19th century, was not so much caused by an increase in fertility, but largely by a decline of mortality particularly of childhood mortality followed by infant mortality
(2) The decline of mortality could largely be attributed to rising standards of living, whereby McKeown put most emphasis on improved nutritional status
(3) His most controversial idea, at least his most disputed idea, was that he questioned the effectiveness of public health measures, including sanitary reforms, vaccination and quarantine
(4)The sometime fierce disputes that his publication provoked around the “McKeown thesis”, have overshadowed his more important and largely unchallenged argument that curative medicine measures played little role in mortality decline, not only prior to the mid-20th century but also until well into the 20th century
It is described by the unrestricted growth of populations resulting in the maximum growth of that population.
Biotic potential
It is the highest possible vital index of a species; therefore, when the species has its highest birthrate and lowest mortality rate.
Biotic potential
The biotic potential is the _____ of the ability of a species to face selection in any environment.
Quantitative Expression
The main equilibrium of a particular population is described by the equation:
Number of Individuals = Biotic Potential/Resistance of the Environment (Biotic and
Abiotic)
Chapman also relates to a “vital index”, regarding a ratio to find the rate of surviving members of a species, whereas;
Vital Index = (number of births/number of deaths) *100
According to the ecologist _______ , the biotic potential could be divided into a reproductive and survival potential.
R.N Chapman (1928)
The survival potential could in turn be divided into—-
Nutritive and protective potentials.
It is the upper limit to biotic potential in the absence of mortality.
Reproductive potential (potential natality)
It is the reciprocal of mortality.
Survival potential
Because reproductive potential does not account for the number of gametes surviving,_____ is a necessary component of biotic potential.
Survival potential
In the absence of mortality—
biotic potential = reproductive potential.
