As most of you know already, I
have a very strong interest in evolutionary psychology and I believe that
taking the evolutionary approach helps a lot in explaining and understanding
human behavior.
One of the theories I believe to
be highly significant and useful in evolutionary psychology is “Life history theory”. This theory explains many apparent paradoxes that we
encounter in our social life and gives very nice insights into understanding
human behavior. Let me present this theory as briefly and comprehensively
as possible.
As I mentioned in earlier posts, any organism, including humans, has two
evolutionary “Macro-Goals” namely survival and successful reproduction. What
is usually known in popular culture as the “principle” of evolution is
“Survival of the Fittest” (sometimes mistaken for survival of the strongest).
Indeed, survival is crucial and all creatures have some sort of survival
driven instincts such as “self-preservation”. If we look a little deeper in the evolutionary process, however, we
will see that survival is in itself irrelevant. If we agree that evolution
is a slow process of selecting genes from one generation to another, mere
survival is by far not enough. If an organism survives for a long time but does
not send its genes into the next generation through reproduction, eventually
its genetic material will be removed from evolution.
To summarize this, mere survival is not enough for the success
of an organism in the evolutionary process. An organism has to reproduce in
order to be part of the long and slow evolutionary process.
At first glance, survival and reproduction are goals that go “hand in
hand”. However, this is not exactly so since during its life an organism
has limited resources. Putting things a bit differently, to a large extent survival and reproduction are competing for the
limited resources available to an organism.
Life History Theory (introduced
by McArthur & Wilson, 1967 and developed in 1975) is derived from general evolutionary
theory and describes the allocation of an individual’s material and
metabolically resources between short term and long term survival and
reproduction. The tradeoff an organism has
to deal with is whether to invest in Somatic Effort - growth and maintenance of
the body and in the case of humans the mind (knowledge, skills) and
Reproductive Effort – attracting a mate, deferring same sex rivals, reproduction
and investment in offspring. Moreover, Reproductive Effort consists of two types
of investments: Mating Effort – resources needed for attracting, retaining
sexual partners and deferring same sex rivals and Parental Effort – resources
needed for the increase of the offspring’s chances of survival and successful
reproduction.
Again taking the evolutionary
perspective, the difference between
reproductive and somatic effort is, in fact, a difference between “reproduction
now” and “reproduction later”, since somatic effort, even if it leads to
higher survival rate or longer life span, has no evolutionary benefit in
itself.
Keeping in mind that there is a
tradeoff between reproduction and somatic effort (survival), organisms vary on
how much of their limited resources are allocated to one or another. Organisms that allocate a lot of effort to
reproduction at the expense of somatic effort are considered to follow a “Fast”
Life History Strategy. Organisms that allocate a lot of effort to somatic
investment at the expense of reproduction are considered to follow a “Slow”
Life History Strategy.
To better understand this,
consider the following example. Cats tend to have a large number of offspring
(between 3 and 6 depending on the age of the mother) twice a year and each
generation of cubs receives about 2 months of parental investment from the
female and virtually no investment from the male. Cats develop sexually rapidly
(a female can have cubs at the age of 10 – 12 months), have relatively short
lives, exhibit high infant mortality, are generally of small size, and show
very little group cohesion. Cats are a very good example of “Fast” Life History
Strategy.
At the other end of the spectrum
are, for example, elephants which have a small number of offspring (one or
two), have a large gestation period of two years, exhibit slow sexual development,
have a low level of infant mortality, live longer, are, in general, of large
size and show high group cohesion. Elephants are a very good example of “Slow”
Life History Strategy.
Humans as specie have a “slow” life history strategy. This is due
to the large amount of time and resources needed for a person to reach
reproductive age.
However, there is a lot of variation within our species, some people tend to
have more children, to have the first child at a younger age and offer less
parental investment, while others tend to have fewer children, have the first
child at an older age and offer higher parental investment. A very salient
example of this within specie variation is the comparison between India and
Europe.
A legitimate question regarding
this variance is “what causes it?” The fundaments of Life history theory
suggest that life history strategy is an
evolutionary adaptation to the environment; thus both the between and within
species variation can be explained by differences in environments that
different individuals have developed and currently live in.
The two broad types of Life
History strategies are evolutionary adaptations to the environment in which a
species has evolved. Species that have a “fast” life history strategy evolved
under unstable and unpredictable conditions. These conditions lead to a
strategy focusing on having more offspring (offspring quantity). For example in
an environment which has numerous threats which lead to a high mortality rate
within a population the normal adaptation would be to adopt a faster life
history strategy because somatic investment will not have evolutionary pay-offs
since an organism would die before getting to reproduce.
Species that have a “slow” life
history strategy evolved under stable and predictable conditions, which lead to
a strategy focusing on the survival of offspring (offspring quality).
In humans, variation in the type of life history strategies adopted can
be attributed to both environmental factors such as high infantile mortality,
short life expectancy due to poor living conditions etc. and to genetic
inherited traits.
As I mentioned earlier, the difference between “fast” and “slow”
life history strategy resides in the allocation of resources between
reproductive effort and somatic effort (survival). There are also differences in how reproductive effort is
distributed between its two (sub)components which are mating effort (acquiring
mating partners) and parental effort (investing in the children).
In the case of a “slow” life history strategy, there is a
larger parental effort and a smaller mating effort. On the other hand, in a “fast” life history there is an emphasis
on mating effort and a relative neglect on parental effort.
Life history strategy is a
complex trait and, as far as I know, there is no unique scale or took to
measure it to its full complexity. There are, however, three proxies that work quite well.
First there is parental investment received by a person. This
parental investment consists of maternal and paternal investment to which it
can be added “nepotistic” investment which is the investment received by a
person from family members other than the parents. People who have received a
low level of parental investment (during childhood) tend to adopt a “fast” life
history strategy, whereas people who have received a large level of parental
investment tend to adopt a “slow” life history strategy.
Second there is childhood socio-economic status. In essence it
measures to what extent a person grew up in a relatively rich or poor family.
People who have grown up in relatively poor conditions tend to adopt a “fast”
life history strategy, whereas people who grown up in relatively rich
conditions tend to adopt a “slow” life history strategy.
Third, there is Socio-Sexual Orientation. This measures the extent
to which a person has long or short term mating goals. In other words if a
person is more inclined to have short term romantic relationships or long term
ones. Socio-Sexual orientation should not be mistaken for “sex drive”. It does
not take into account the number of sexual intercourse instances; rather it
looks at the number of sexual partners a person has. People with a more
restricted socio-sexual orientation (fewer partners and more serious
relationships) tend to adopt a “slow” life history strategy, whereas people
with a more unrestricted socio-sexual orientation tend to adopt a “fast” life
history strategy.
When it comes to Socio-Sexual
Orientation there is a significant gender difference, namely that on average
men are more unrestricted than women. However, this is not to say that men are
unrestricted and women are restricted because there is very large within gender
variation. Putting it a bit differently, there are women who are more
unrestricted than the average of men and there are men more restricted than the
average of women.
Which one of these proxies is
better to measure one’s type of life history strategy I can’t say. What I can
say is that all of them capture a
significant part of the complex trait Life History Strategy, but none captures
the entire trait. Also, from my own experience with research in this area
there are some correlations between the proxies, but none of them is very high,
meaning that each of them captures some related but distinct aspects of life
history strategy.
To summarize, life history strategy captures the tradeoff between
allocating resources for somatic investment and reproductive effort. People
with a “fast” life history strategy allocate more resources to reproductive
effort than to somatic investment. People with a “slow” life history strategy
allocate more resources to somatic investment than to reproductive effort.
When it comes to reproductive effort, people with a “fast” life history
strategy allocate more resources to mating effort (getting mating partners) and
less to parental investment. People with a “slow” life history strategy
allocate more resources to parental investment and less to mating effort (getting
mating partners).
As I mentioned in the beginning of
this post, I believe that Life History
Theory has many significant implications in practice and it helps explain some
apparent paradoxes in social life. Let me explain a bit more.
As you may know, I am Romanian
and Romania is not a very rich country. Despite (or in fact because of) this
the number of status brand automobiles (such as BMW, Mercedes, Bentley etc.)
per capita is significantly larger than in more richer countries in the West of
Europe such as The Netherlands (where I life now), France, Germany etc.
Another interesting fact about my
home-country is that in 2009 when the country was hit by a severe recession
(-7% of GDP) the sales for Ferrari cars actually increased compared to 2008
when the economy was doing well.
These facts are more or less the
same for all emerging economies in the East of Europe and Africa, South-East
Asia etc. At least from my experience when crossing the former “iron curtain”
(the border between western democratic countries in Europe and Eastern former
communist countries) there is a clear difference in the type of cars that are
seen on the roads. In the west there are significantly fewer expensive status
cars, whereas in the east their proportion is huge.
Of course, there are more causes
for this difference, but one of them is related to Life History Theory. In more poor and uncertain environments
many people are more on the side of a “fast” life history strategy and it is
only natural for them to invest more in “mating effort” which includes
enhancing one’s status through conspicuous consumption.
I have heard a sad but
interesting story about a very poor family who somehow got to be presented on
TV before a major Christian holyday. In brief, they were so poor that they
couldn’t get a decent meal for that holyday. After the story being presented on
TV, a rich man gave that family about 800 Euros (which is a lot of money) to
have a decent celebration of the holyday. What that family did with the money…
well they bought an iPhone…
Apparently this type of behavior is really stupid and I don’t argue
with that. However, this behavior is natural. Simply people with a “fast” life
history strategy invest a lot of their often few resources in their status.
Unfortunately, buying iPhones or BMWs does not get someone out of poverty.
Another difference between “fast” and “slow” life history strategy is
the attitude towards risk. In general all people are risk averse, but again
there is variance within our specie on how risk averse or risk seeking we are. People with a more “fast” life history
strategy are more willing to take risks especially when they feel a
potential threat to their life or well-being (in other words, environmental threats
such as recessions, wars, natural disasters etc.). On the other hand, people with a more “slow” life history
strategy are more risk averse and avoid taking risks even when there are
environmental threats.
This difference in attitude
towards risk explains why the people with very limited possibilities are the
ones that gamble their last pennies and are likely to get loans with very risky
costs.
Before continuing with the
argument, I have to say that having a “fast”
life history strategy is not wrong neither is having a “slow” life history
strategy. Each of them is an adaptation to the environment. Even if some
consider that having a “fast” life history strategy is wrong, people who are
more “fast” than “slow” in life history strategy are not to be blamed for their
behavior. They do what is natural for them to do.
In my opinion the “fast” life history strategy contributes to what I call
“Self-enforcing poverty”. If people in very poor societies have many
children, then the next generation will be at best as poor as their parents
were.
Even if there is an influx of money in societies dominated by “fast”
life history strategy, this money will be spent on increasing status which can
lead to a runaway conspicuous consumption race. Unfortunately status
products will not make people less poor, nor will they give them more opportunities
for future development.
In fighting poverty, one crucial
aspect is to understand which the sources are of a “fast” or “slow” life
history strategy. To a certain extent, life history strategy is inherited through
genes, thus very little can be done in this area. At the same time, there is a
component inherited through nurture and there things can be improved. Moreover,
in stable predictable environments the differences between “fast” and “slow”
life history strategies are very small, but things change when the environment
is unpredictable and offers cues of life threats such as high infantile
mortality, high incidence of diseases, wars etc.
Environments can be changed… and controlled.
Note: This post is documented
from:
Griskevicius, V., Tybur, J.M.,
Delton, A.W., Robertson, T. E. (2011). The Influence of Mortality and
Socioeconomic Status on Risk and Delayed Rewards: A Life History Theory Approach.
Journal of Personality and Social Psychology, 100(6), 1015–1026.
Figueredo, A. J., Vasquez, G.,
Brumbach, B. H., Sefcek, J. A., Kirsner, B. R., Jacobs, J. W. (2005). The
K-factor: Individual differences in life history strategy. Personality and Individual
Differences, 39(8), 1349–1360.
Figueredo, A. J., Vasquez, G.,
Brumbach, B. H, Schneider, S.M. R. (2010). The heritability of life history
strategy: The k‐factor, covitality, and personality. Biodemography and Social Biology,
51(3-4), 121-143.
Simpson, J.A., & Gangestad, S. W. (1992). Sociosexuality and Romantic Partner Choice. Journal of Personality, 60(1), 31–51.
Simpson, J.A., & Gangestad, S. W. (1992). Sociosexuality and Romantic Partner Choice. Journal of Personality, 60(1), 31–51.
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