Population lecture - Center for Bioinformatics

Resolving Global Overpopulation
Chris Bystroff
Biology / Computer Science
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Overpopulation:
1. Discussing overpopulation is like putting a turd in the punchbowl
!
Why we tend to avoid the issue.
2. Are we smarter than a yeast?
!
Equations for population growth and decline.
3. Sustainability versus compassion.
!
Lifeboat ethics.
4. The road ahead.
!
Technologies and choices.
1. Discussing overpopulation is like putting a turd in
the punchbowl
Why we tend to avoid the issue.
3
Human population, the last 700 years
7
6
billions
5
4
3
2
1
1300
1400
1500
1600
1700
1800
1900
2000
overcrowding
extinctions
Wilson, Edward O. The diversity of Life, The Belknap Press of
Harvard university press, Cambridge, Mass.1992.
loss of biodiversity
degradation of arable land
invasive species
What will come of this?
Disease
10
War!
11
Famine!
12
Typical reaction at this point
13
How would you react?
Choose 1
1. Continue eating and ignore him/her.
2. Look at watch. Make excuse. Get out
of there as fast as possible.
3. Engage in an animated conversation
about the end of life as we know it.
4. Reassure them that population is not a
problem.
14
Cognitive dissonance
Cognitive Dissonance -- an uncomfortable feeling caused
by holding conflicting ideas simultaneously.
reactions to varying degrees of dissonance
Level of
Dissonance
example:Music example: Science
Human
reaction
low
twinkle twinkle
little star
basic
arithmetic
Boring. Pay no
attention.
medium
J.S. Bach
physics or
biology
Stimulating.
Pay attention.
high
Anton
Schönberg
overpopulation
Irritating.
Flee!!!
16
reproductive instincts
se
s
leads to
ea
cr
guilt trip
Your brain on overpopulation
inhibits
ith
co
nfl
personal time
investment
other time
investments
s
ict
sw
demands
tes
s
wa
ie
reproductive
austerity
irresolvable
conflicts
with
pe
perceived
as
ed
rci
ev
ibit
s
implies
as
inh
ved
political issue
de
personal
isolation
pl
cei
outside of the
mainstream
im
per
as
Discussing population
How will overpopulation
be resolved?
Choose one.
(A) War.
(B) Disease.
(C) Famine.
✓(D) Other.
18
Are we smarter than a yeast?
Equations for population growth and decline.
19
Human population, the last 2000 years
7
6
billions
5
4
3
2
1
0
...
1300
1400
1500
1600
1700
1800
1900
2000
Exponential growth
dN
= ! 0 N ! "0 N = #0 N
dt
#$%#!"
&$%!&"
!"!#$%&"'(
-$%!&"
,$%!&"
+$%!&"
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)$%!&"
($%!&"
'$%!&"
#$%!&"
!"
!"
*!!"
#!!!"
#*!!"
'!!!"
'*!!"
(!!!"
&)*(
Population growth is proportional to population. This is a normal
growth curve for no predation, no food/space limitations.
21
Malthus
"It is an obvious truth, which has been
taken notice of by many writers, that
population must always be kept down
to the level of the means of
subsistence; but no writer that the
Author recollects has inquired
particularly into the means by which
this level is effected..."
-- Thomas Malthus, 1798
An Essay on the Principle of
Population
22
Death rate > birth rate lead to
exponential population decline
dN
= ! 0 N ! "0 N = #0 N
dt
α0 < 0
N
time
23
boom/bust of isolated species
Yeast in 10% sugar solution
Large mammal with no predators
24
Michael Mills, Dept of Psychology, LMU
ECOME - a simulated evolving consumption web
2
CO
2
CO
life
Bystroff C, DeLuca S, & McDaniel CN (2005) ECOME: A simple model for an evolving consumption web. IEEE Computational Systems
Bioinformatics Conference - Workshops 8-11 Aug. 2005 pp 260 - 261
• Species are measured in units of “biomass”
• Species can be autotrophs (green) or heterotrophs
(red)
• Plants catalyze CO2 --> CH
Plants grow proportional to biomass.
• The sun's maximum total input to the
food web is fixed.
All plants stop growing when the sum
total biomass ≥ sun limit
• Primary consumers (herbivores) get
biomass from plants
Secondary consumers (carnivores) get
biomass from other animals.
etc.
• All species also catalyze CH --> CO2.
i.e. All species lose biomass to respiration
and natural death, at a constant rate.
• Predator species collapse when prey is
scarce.
plant mass that is left
new mass needed to survive =
current mass * k.
• ...along with the prey species.
endangered
species
• Fed fraction grows
fed fraction
• Unfed fraction dies.
unfed fraction
• ...becomes CO2.
unfed fraction dies
...collapse follows on the next cycle.
• Hollings functions modify predator/prey
relationship. Predators can starve while
prey still exists, but is scarce.
Too small.
Predator
can't find it.
• Speciation.
http://www.bioinfo.rpi.edu/bystrc/ecome/local.mpeg
39
Populations are inherently unstable
ECOME log(biomass) vs time.
40
Boom/bust oscillations are
natural
41
http://io.uwinnipeg.ca/~simmons/16cm05/1116/16popbio.htm
Conclusions from ECOME experiment
• Plant populations grow to a limit and
stabilize.
• Animal populations boom and bust.
• Animal species collapse if
– They are eaten
– They eat too much
• Ecosystems collapse if
– They are too small
– They don’t evolve, or evolve too slowly
42
Can humans survive by evolving faster?
Cultural evolution is faster than evolution
Cultural evolution is Lamarckian
+
+
Disuse
Use
45
Prediction for humans?
pop
time
46
Collapses in past human societies
A short list
Mashkan-shapir
2300 BCE
Rome
400
Maya
800
Angkor
1220
Anasazi
1300
Ghana/Mali/Songhai
1300-1500
Europe
1348
Greenland Norse
1450
Easter Island
1860
Rwanda
1994
47
Logistic growth
dN
= (! 0 ! !1 N ) N
dt
Carrying capacity K=α0/α1
#$%#!"
&$%!&"
!"!#$%&"'(
-$%!&"
,$%!&"
+$%!&"
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)$%!&"
($%!&"
'$%!&"
#$%!&"
!"
!"
*!!"
#!!!"
#*!!"
'!!!"
'*!!"
(!!!"
&)*(
Death rate increases and/or birth rate decreases with
population until the birth rate matches the death rate, at
which point the population plateaus.
48
Logistic growth models are used, carrying capacity unknown.
49
population (consumption)
Overshooting the carrying capacity
degrades the carrying capacity
carrying ca
theoretical upper limit
to carrying capacity
pacity
overshoot
degraded
carrying
capacity
Carrying capacity is the
amount of food (and other
resources) available to
support human life
sustainably. If resources
(such as wild fish) are
overused, they do not
recover as quckly,
degrading the carrying
capacity.
time
50
Peak Oil
http://www.peakoil.net/
Food production, heat, transportation all depend largely on oil,
a non-renewable resource. Are we spending our savings?
51
Non-renewable water
NASA ASTER image of an approx. 557 mi² area of fields (1443 km²)
in Kansas which are watered from the Ogallala aquifer with center
pivot irrigation systems.
The Ogallala aquifer is being
depleted due to irrigation.
...while food depends directly on water and oil.
53
I = Environmental impact
I = P*A*T
Impact = Population * Affluence * Technology
C = Carrying capacity, which is a function of (food
supply, water supply, climate)
C has a theoretic maximum.
C is a function of the time.
C is degraded by I.
C (t ) = C! (1" I (t ))
Creating a negative feedback loop.
dP
dI
dC
dP
!
!"
!"
dt
dt
dt
dt
54
Demographic pyramid.Baby booms and
busts, oscillating trends.
55
Scenarios for logistic growth
Constant carrying
capacity
pop
pop
cycles of degraded/
recovering carrying
capacity
time
56
Von Foerster equation: Doomsday growth
1
dN
= !0 N k N
dt
(
)
growth rate is a monotonically increasing function of N
Integrating yields
#$%#!"
&$%!&"
" t0 ! t1 %
N t = N1 $
'
# to ! t &
!"!#$%&"'(
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,$%!&"
+$%!&"
*$%!&"
k
)$%!&"
($%!&"
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!"
!"
*!!"
#!!!"
#*!!"
&)*(
'!!!"
t0
'*!!"
t0 is
doomsday.
People behave increasingly as one unit. Life gets easier. Less competition
for resources within the species. Birth rate increases and/or death rate
decreases with population.
H. von Foerster, PM Mora, LW Amiot (1960) “Doomsday: Friday 13 Novermber, A.D. 2026” Science132:1291-95.
57
Log-log plot of historical
human population versus
time (lower x-axis) and doomstime (upper x-axis). The fit is
hyperbolic.
H. von Foerster, PM Mora, LW Amiot
(1960) “Doomsday: Friday 13 November,
A.D. 2026” Science132:1291-95.
58
Adding oscillating behavior makes the fit even better.
59
Doomsday scenario
pop
time
enough said?
60
,7
1
1
20
n
llio
i
b
,6
9
9
19
n
llio
i
b
,5
8
8
19
Log-log plot of historical
human population versus
time.
n
li lio
b
,4
6
7
19
n
li lio
b
,3
0
6
19
Are we at “regime shift1”
1Johansen
n
li lio
b
Population data
since 1960
H. von Foerster, PM Mora, LW Amiot
(1960) “Doomsday: Friday 13 November,
A.D. 2026” Science132:1291-95.
& Somette (2001) Finite-time singularity in the dynamics of world
population, economic and financial indeces. Physica A, 294(3):465-502.
61
What is happening?
(a) People are getting smarter, seeing the
writing on the wall, and having fewer children.
(b) Nature is fighting back and the carrying capacity is
making itself felt.
62
Trend in Total fertility rate = children per woman
von Foerster estimated we would have to cut fertility by a factor of two from 1960 levels.
63
Drought helped cause Syria’s war. Will
climate change bring more like it?
•
By Brad Plumer Washington Post September 10, 2013 at 9:34 am
“We looked at the period between 2006 and 2011 that preceded
the outbreak of the revolt that started in Daraa. During that
time, up to 60 percent of Syria's land experienced one of the
worst long-term droughts in modern history. This drought
— combined with the mismanagement of natural resources by
[Syrian President Bashar] Assad, who subsidized waterintensive crops like wheat and cotton farming and promoted
bad irrigation techniques — led to significant devastation.
According to updated numbers, the drought displaced 1.5
million people within Syria.”
Reds and oranges highlight
lands around the
Mediterranean that
experienced significantly
drier winters during
1971-2010 than the
comparison period of
1902-2010.
Werrell, C., Femia, F., & Slaughter, A.
M. (2013). The Arab spring and climate
change. A climate and security
correlations series. Center for American
Progress et The Center for Climate and
Security.
64
Civil unrest correlates with food prices.
FIG. 1: Time dependence of FAO Food Price Index from January 2004 to May 2011. Red dashed
vertical lines correspond to beginning dates of \food riots" and protests associated with the major
recent unrest in North Africa and the Middle East. The overall death toll is reported in parentheses
[26{55]. Blue vertical line indicates the date, December 13, 2010, on which we submitted a report to
the U.S. government, warning of the link between food prices, social unrest and political instability
[56]. Inset shows FAO Food Price Index from 1990 to 2011.
The Food Crises and Political Instability in North Africa and the Middle East Marco Lagi, Karla Z. Bertrand and Yaneer Bar-Yam
New England Complex Systems Institute
65
Q: Are we smarter than a yeast?
A: As individuals, Yes.
As a species, maybe not. You decide.
“A person is smart. People are dumb,
panicky, dangerous animals and you
know it.”
--Tommy Lee Jones character “K” in “Men in Black”
66
3. Sustainability versus compassion.
Lifeboat ethics.
67
Conflicting ethics
bad
good
death
unsustainable
life
sustainable
68
bad is good, good is bad
we are here
life
e
a bl
n
i
sta
u
s
un
ble
a
n
ai
ust
s
ble
a
n
tai
s
u
uns
death
69
Lifeboat Ethics
Carrying capacity = number of people the boat (The Earth)
can hold safely.
72
73
4. The road ahead.
Possible futures
74
7,190, 000, 000 ppl
a growing chorus
a growing chorus
"global warming, the stunning rise of middle
classes all over the world, and rapid population
growth have converged in a way that could make our
planet dangerously unstable."
Thomas Friedman, NY Times columnist,
author of “Hot, Flat and Crowded”
77
Statue of Norman Borlaug installed at US Capitol, April 1, 2014
“Most people still fail to
comprehend the
magnitude and menace
of the 'Population
Monster'"
--Norman Borlaug,
father of the “Green
Revolution”
© 2009 Population Reference Bureau. All rights reserved. www.prb.org
© 2009 Population Reference Bureau. All rights reserved. www.prb.org
decrease the birth rate!
80
Unintended pregnancy in the US, 1994
In 1994,
49% of pregnancies were unintended
54% of these ended in abortion
48% of women have had ≥1 unplanned pregnancy
28% of women have had ≥1 unplanned birth
Highest unintended pregnancy rate among women 18-24,
unmarried, low-income, minority.
Stanley K. Henshaw. Unintended Pregnancy in the United States. Family Planning Perspectives
30(1), January/February 1998
81
Fertility correlates with poverty
From the UN, Economic and Social Council Commission on Population and Development
3 April 2009
82
Fertility Rate vs GDP
replacement rate
83
CIA World Fact Book
Education and healthcare
= lower fertility
84
Total number of grant opportunities listed on Grants.gov which
include the word “overpopulation” anywhere in the full
announcement.
✴
2
http://www.grants.gov/search 21-Feb-2010
✴Agencies:
1.
2.
Bangladesh USAID-Dhaka
Pakistan USAID-Islamabad
same search in 2012
✴
0
http://www.grants.gov/search 30-Nov-2012
85
Contraception is the greenest technology
Cost per ton of CO2 abatement
Family planning
wind
solar
clean coal
plug-in hybrids
electric vehicles
$7
$24
$51
$57 - 83
$92
$131
86
Contraceptive vaccines
Besides the availability of the present methods of birth control, the population explosion
and unintended pregnancies continue to pose major public health issues worldwide. The
world population has exceeded 6.43x109 (World POPClock projection, 2005) and
increasing by 1x109 every 12 years. Ninety-five percent of this growth is in the
developing nations. In the USA, half of all pregnancies are unintended, which result in
>1x106 elective abortions annually (Henshaw, 1998; Grow and Ahmed, 2000). This calls
for a better method of contraception that is acceptable, effective and available both in the
developed and developing nations. An ideal contraceptive method should be highly
effective and safe, inexpensive, have a prolonged duration of action, be rapidly
reversible and easily accessible, require infrequent administration, and be capable
of private use (Contraception Online, 2004). A contraceptive vaccine (CV) has been
proposed as a valuable alternative that can fulfill most, if not all, of the properties of an
ideal contraceptive. Since the developed and most of the developing nations have an
infrastructure for mass immunization, the development of vaccines for contraception is
an exciting proposition.
Rajesh K.Naz,4, Satish K.Gupta, Jagdish C.Gupta3, Hemant K.Vyas3 and
G.P.Talwar3 Recent advances in contraceptive vaccine development: a minireview. Human Reproduction Vol.20, No.12 pp. 3271–3283, 2005
A contraceptive vaccine
•
•
•
Family planning provides the greatest decrease in environmental
impact per dollar spent. (Cost per ton of CO2 abatement. Optimum Population Trust, Aug 2009.)
Non-barrier, non-hormonal, non-device, long-lasting, quickly
reversible, inexpensive.
Roughly 1/2 of all pregnancies are un-planned. 1/2 of those lead
to un-wanted children.
vaccination
Ca2+
TxDxW motif
catsper
Ca2+
+ carrier (flagellin
or human
papilloma virus)
89
Bystroff Lab
www.bioinfo.rpi.edu/bystrc/
ECOME: Carl McDaniel, Sam DeLuca
Catsper vaccine: Raz Naz, Danielle Basore
Think Globally,
Act Locally.
Limits to food
production
•
•
Arable land -- finite, decreasing yields
•
•
Fisheries -- predicted to collapse by 2050 (R.
Water -- surface, aquifer, fossil water
irrigation
Ellis, “Empty Ocean”)
Climate change -- high temperatures lead to
crop failure. (failed pollination, insect dependence)
Three scenarios that would each reduce
carbon emissions by 29% by 2050
1
Decrease population growth from two
billion to one billion by 2050
2
Double fuel efficiency of 2 billion cars
from 30 mpg to 60 mpg
3
Replace coal with 700-fold increase in
solar power
Upper limit to carrying capacity
•
Maximum total production rate = Total
sunlight hitting the Earth * Maximum
efficiency in conversion to food
•
Total consumption rate = total population *
individual consumption rate
•
Total consumption rate ≤ Total production
rate (obviously!)
Eric Pianka, Denton A. Cooley Centennial
Professor of Zoology, UT Austin.
The Ebola Solution
Ebola zaire with a 90% mortality rate in humans,
is spread only by direct contact between people.
Ebola reston infects only non-human primates
but is airborne transmissable.
It is only a matter of time before the more
pathogenic strain E. zaire gains the ability to be
airborne transmissible, like its homolog E.
reston.
From The Vanishing Book of Life on Earth
Eric Pianka, Denton A. Cooley Centennial
Professor of Zoology, UT Austin.
The Johnny Anti-Appleseed Solution
1. Design a molecule that could that
could bind DNA make people sterile.
2. Design another molecule that would
unmask the first and make the person
fertile, just for a short time.
3. Make people work for the second pill*.
You’d get responsible parenthood. No
more unwanted children, no juvenile
delinquents...
*Married couples only?
“First...bless
everyone with
infertility.” --E.P.
World Population Growth Is Almost Entirely
Concentrated in the World's Poorer Countries.
World Population (in Billions): 1950-2050
Source: United Nations Population Division, World Population Prospects, The 2008 Revision.
© 2009 Population Reference Bureau. All rights reserved. www.prb.org