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Current Aging Science, 2014, 7, 17-24 17
Human Evolution, Life History Theory, and the End of Biological
Reproduction
Cadell Last*
The Global Brain Institute (GBI), Brussels, Belgium
Abstract: Throughout primate history there have been three major life history transitions towards increasingly delayed
sexual maturation and biological reproduction, as well as towards extended life expectancy. Monkeys reproduce later and
live longer than do prosimians, apes reproduce later and live longer than do monkeys, and humans reproduce later and live
longer than do apes. These life history transitions are connected to increased encephalization. During the last life history
transition from apes to humans, increased encephalization co-evolved with increased dependence on cultural knowledge
for energy acquisition. This led to a dramatic pressure for more energy investment in growth over current biological re-
production. Since the industrial revolution socioeconomic development has led to even more energy being devoted to
growth over current biological reproduction. I propose that this is the beginning of an ongoing fourth major primate life
history transition towards completely delayed biological reproduction and an extension of the evolved human life expec-
tancy. I argue that the only fundamental difference between this primate life history transition and previous life history
transitions is that this transition is being driven solely by cultural evolution, which may suggest some deeper evolutionary
transition away from biological evolution is already in the process of occurring.
Keywords: Aging, biology, culture, evolution, future, human evolution, life history theory, primates.
INTRODUCTION
In this issue, we are attempting to provide a multi-
disciplinary perspective on the elimination of aging (from
here referred to as "radical life extension"). The first thing
that must be considered when discussing radical life exten-
sion (RLE) are the practical consequences such an achieve-
ment would have on human growth and reproduction. Popu-
lar and political opposition to RLE primarily stems from the
belief that such a development would lead to catastrophic
overpopulation issues.
In this paper I would like to specifically address how
human growth and reproduction should be affected by the
achievement of RLE. Such an understanding would help us
properly prepare for the resulting demographic transforma-
tion, as well as restructure popular and political dialogue
around real problems, as opposed to imagined problems.
In order to accomplish this I am proposing a straightfor-
ward methodology dependent on A) the evolution of human
growth and reproduction, B) a situation of this evolution
within the explanatory framework of Life History Theory
(LHT), and C) an extrapolation of modern developed world
sexual behaviour into the near-term future (~2040-2050).
With such an approach we should be able to understand the
evolved life history of humanity and how major technologi-
cal breakthroughs related to RLE should affect our growth
and reproduction patterns.
Hopefully such an analysis will give demographers,
historians, anthropologists, biologists and futurists the
*Address correspondence to this author at the Global Brain Institute (GBI),
Brussels, Belgium; Tel: 647-464-8831; E-mail: cadell.last@gmail.com
framework they need to better understand the future of the
human population.
HUMAN GROWTH AND REPRODUCTION
Every organism has an evolved life history pattern. A life
history pattern is the way time and energy are allocated be-
tween growth, maintenance, and reproduction [1]. Through-
out the evolutionary history of primates there have been
three major life history transitions towards later sexual matu-
ration and longer lifespan. These transitions occurred be-
tween [2]:
• Prosimians --> Monkeys
• Monkeys --> Apes
• Apes --> Humans
The life history characteristics of our closest relatives, the
hominoids (e.g. chimpanzees, bonobos, gorillas) is particu-
larly exaggerated towards later sexual maturity and longer
life expectancy relative to the rest of the primate order [2].
That general pattern resulted in extreme degrees of parental
care over long developmental periods [3]. However, humans
have an even more extreme pattern. We dedicate more time
and energy towards growth than any other primate species
[4]. The life history consequences are dramatic, as more in-
vestment in growth pushes reproduction back further, and
significantly lengthens our evolved maximum lifespan.
Whereas orangutans, gorillas, and chimpanzees sexually
mature between 8-10 and have an evolved lifespan between
40-50 [5], most humans reach full sexual maturity between
18-20 [6] and have an evolved average life expectancy ~80
(Table 1) [2].
1874-6128/14 $58.00+.00
© 2014 Bentham Science Publishers
18 Current Aging Science, 2014, Vol. 7, No. 1 Cadell Last
Our extreme drift towards later sexual maturation and
longer lifespan led to two interesting emergent parenting
traits unique among even our fellow hominoids: reproductive
support by post-reproductive individuals and extensive male
support of reproduction via provisioning of both females and
offspring [4, 7]. Throughout human evolution it did not take
a village to raise a child, but it literally required a band of
close kin. Due to this organization, a few other novel traits
emerged:
• Reproductive support by post-reproductive in-
dividuals (specifically post-reproductive fe-
males) likely led to the development of meno-
pause [8, 9]. Menopause allows older females
to shift time and energy away from their own
reproduction and towards their close kin's re-
production [9].
• Maintenance of extensive male support of repro-
duction via provisioning of both female and off-
spring likely led to concealed ovulation and con-
tinuous, nonreproductive sexual activity [10, 11].
Both traits help maintain extended male-female
relationships [3].
These "uniquely unique" features of human life history
relate back to one central adaptation: the human brain, and
more specifically the neocortex [12]. For a primate of our
body and brain size, the human neocortex is 35-60% larger
than expected [13]. And it is this physical adaptation that is
responsible for all of our behavioural uniqueness, like a the-
ory of mind [14], language [15], music, art, and high intelli-
gence [11].
Since the human life history pattern has grown diver-
gent from our fellow hominoids we must address when it
evolved. Growing consensus suggests that our life history
pattern started to co-evolve gradually with the emergence
of the genus Homo approximately 2 million years ago.
Techniques for understanding the evolutionary emergence
of modern human life history is related to understanding
the relationship between life expectancy and brain size in
mammalian species [5, 16], as well as the relationship
between lifespan and age-at-first reproduction [17, 18].
The paleoanthropological record provides us with both the
cranial and the bone and dental evidence needed to piece
together the evolution of human encephalization quotient
(EQ) as well as average sexual maturation. As a result, we
can estim ate the evolution of long human lifespan and the
evolution of modern human life history more generally
[6].
From the contemporary fossil hominin record we see
evidence for three or four major transitions in the emergence
of modern human life history related to encephelization and
sexual maturation (Table 2) [9, 11].
Although this evidence suggests that longer lifespan
emerged in punctuated equilibrium bursts [11], the bone
and dental evidence suggests that the main push towards
later sexual maturation came with the emergence of post-
Homo erectus hominids [19, 20]. We know that the aus-
tralopithecines had a life history pattern sim ilar to extan t
great apes (i.e. "live fast and die young") [19]. Early
Homo as well as Homo erectus/ergaster forms were un-
like either extant hominoids or modern humans [21]. Both
dental evidence and cranial size evidence suggests tha t
they were exhibiting the early stages of what would even-
tually become the modern human life history, as they
were aging slower, reproducing later, and living longer
than their australopithecine predecessors [21, 22]. There
are currently some difficulties understanding exactly
when the modern life history pattern evolved post-Homo
erectus but it is present in the Upper Paleolithic [6].
However, understanding when our life history evolved is
not the same as understanding how our life history evolved.
And for that we will need to explore Life History Theory
(LHT).
Table 1. Great Ape and human life histories
Species
Sexual Maturity
Life expectancy
Orangutans (Pongo)
9-10
40
Gorillas (Gorilla)
8-9
40-45
Chimpanzees (Pan)
8-9
45
Human (Homo)
18-20
75-85
Table 2. Major transitions in human life history
Species
Time (mya)
Cranial Capacity (cc)
Estimated: Sexual Maturity / Life Expectancy
Australopithecines
6-4
450
10
50
Homo habilis
2
600
12-13
60
Homo erectus/ergaster
1.7-0.5
800
15-16
70
Archaic humans
0.3-0.1
1,300
18
80
Human Evolution, Life History Theory Current Aging Science, 2014, Vol. 7, No. 1 19
LIFE HISTORY THEORY AND HUMAN EVOLU-
TION
The history of life can be conceptualized as the history of
variant chemical structures harvesting energy to create ever
more complex replicates of similar forms [23]. Life History
Theory (LHT) attempts to explain the "trade-offs" that occur
as a result of this process [24]. The three pertinent facets of
life history to consider include how organisms spend energy
on growth (i.e. traditionally investment in somatic cells),
maintenance (i.e. avoidance of mortality), and reproduction
[1, 12, 19]. By dedicating energy towards growth and main-
tenance, an organism can enhance future reproduction [2].
Growth and maintenance have traditionally been conceptual-
ized as "somatic effort" (i.e. somatic cell diversification and
replacement, see [24]). On the other hand, organisms can
also dedicate energy towards reproduction. By dedicating
energy towards reproduction, organisms must invariably
reduce the amount of energy dedicated towards growth and
maintenance, as well as reduce the chances of reproducing in
the future [23].
Throughout this entire process, finite energy budgets
fundamentally cause the aforementioned trade-offs. If energy
were unlimited, organisms could in principle start reproduc-
ing soon after birth (i.e. no trade-off between growth and
reproduction) and preserve themselves indefinitely (i.e. per-
fect maintenance) [23]. But throughout the entirety of bio-
logical evolution, energy has never been free and abundant,
it has always been costly and scarce. Therefore, all organ-
isms must spend it strategically, in a way that best maxi-
mizes fitness [1].
In sum, finite energy budgets can be used for the contin-
ued growth and maintenance of the organism (which in-
creases chances of future reproduction), or finite energy
budgets can be dedicated towards replication (which de-
creases the chances of future reproduction). As a result of
this trade-off, an entire organisms existence is about finding
a strategic balance between current and future reproduction.
For our purposes, this theory can help us explain the di-
vergent reproduction and mortality patterns in humans [25].
So what evidence do we have to work with? Remember,
there are four divergent human life history characteristics (as
summarized above) [4]:
• Extended developmental period (i.e. childhood)
• Long life span
• Reproductive support from post-reproductive indi-
viduals
• Extensive reproductive support from males
We also know that these exaggerated and unique life his-
tory features evolved with larger brain size, specifically large
neocortex size, which is also a unique feature among hu-
mans. The dominant LHT explaining this emergence is that
our extreme intelligence, as produced through our enlarged
neocortex, co-evolved in response to gradual dietary shifts to
high calorie food sources [4]. Throughout the punctuated
equilibrium-like bursts in brain size, we find evidence of
substantial transitions to exploitation of increasingly diverse
and meat-abundant diets [9, 26, 27]. Importantly, the exploi-
tation of these diverse and meat-abundant diets were
achieved via the construction of increasingly complex tech-
nology [28].
What does this all mean for our exaggerated shift in life
history towards longer developmental periods and longer life
spans? First and foremost, it meant that our ability to effi-
ciently extract more energy from our environment was de-
pendent on inherently cultural and technological processes.
These processes are in turn facilitated by the acquisition of
increasingly high levels of knowledge, skills, and social co-
ordination, which require longer developmental periods dedi-
cated to learning [4]. Due to the high levels of learning
needed in order to maximize adult survival, our ancestors
invested more energy in growth to maximize future repro-
duction [29]. An adult-sized, fully mature five-year old hu-
man could simply not compete with an adult-sized, fully
mature twenty-year old human [12]. Therefore, childhood
became an intellectual and social stage of development re-
quiring increasingly large amounts of time and energy at the
expense of current reproduction [12]. We have our funda-
mental life history trade-off.
MODERN WORLD
Throughout modern human (i.e. Homo sapiens sapiens)
pre-historic and historic evolution our life history patterns
have not diverged from the evolved pattern. In both hunter-
gatherer and agricultural systems, we allocated time and en-
ergy towards growth and reproduction at roughly the same
intervals. This may at first seem strange considering massive
socio-sexual changes resulted from the emergence of defen-
sible and heritable wealth in agricultural systems [12]. Ex-
amples include [30, 31, 32]:
• Higher emphasis on symbolically mediated long-term
pair bonds (i.e. marriages)
• Patrilineal inheritance
• Exaggerated emphasis on division of labour
The reason these changes during the agricultural revolu-
tion did not significantly alter our life history pattern was
because energy remained costly and scarce for the large ma-
jority of humans, which in turn resulted in similarly high
fertility and mortality rates. If anything, fertility and mortal-
ity rates on average increased slightly in agricultural systems
in comparison to hunter-gatherer systems [33]. Therefore, all
human life before the modern world was characterized by
15-20 years of "pre-reproductive" life, a post-reproductive
life-span that could last 30-40 years, and an organization
including extensive reproductive support from adult males
and post-reproductive females. This evolved life history
strategy proved best for maximizing fitness.
Enter the Industrial age. Most historians agree that the
Industrial Revolution started in England approximately 200-
250 years ago and diffused quickly throughout Western
Europe, the United States of America, and Britain's settler
colonies (e.g. Canada, Australia, New Zealand, etc.) in the
19th century [34, 35]. This revolution released new energy
into our system from fossil fuels and ushered in the era of
very rapid technological progress [36]. This new Industrial
system led to massive demographic changes as industrializ-
ing regions of Europe and North America experienced a
20 Current Aging Science, 2014, Vol. 7, No. 1 Cadell Last
sharp decline in both mortality and fertility [12]. For the first
time in modern human history, some human populations had
experienced a change in their life history pattern.
Overall the demographic transition is characterized by
two main trends. The first trend is a reduction of fertility to
replacement or below-replacement levels (~2.1). The second
trend is a reduction of mortality that allows most individuals
in society to reach an advanced post-reproductive age (~80).
Both trends are universally associated with socioeconomic
development (i.e. "modernization") and a transition from a
pre-industrial to an industrialized economy [33]. Reduced
fertility primarily results from the further extension of
"childhood". However, it is probably more accurate to state
that reduced fertility results from continually delayed bio-
logical reproduction post-sexual maturation. The continued
trend towards delayed biological reproduction was again
accompanied by a further intensification of parental invest-
ment, and parents choosing to invest time and energy in the
"quality" of offspring as opposed to the "quantity" of off-
spring [33].
This transition to a new life history pattern is not the re-
sult of one specific culture or "Westernization". The demo-
graphic transition is directly the result of socioeconomic de-
velopment and industrialization. In the beginning of the 21st
century, the first regions of the world to industrialize have
already completed the demographic transition (e.g. Europe,
Northern America, Japan, Australia, New Zealand, etc.) [37].
Many newly developed countries in East Asia have also
completed (or are nearing completion) of their demographic
transition [38]. Furthermore, much of Asia, Latin America,
and most recently, Africa, have experienced the beginnings
and maturation of the demographic transition [37]. Many
experts expect the full realization of the demographic transi-
tion to manifest globally by the year 2050, as long as current
socioeconomic industrialization trends continue [37]. As far
as the developed world is concerned, the two trends associ-
ated with the demographic transition are expected to con-
tinue accelerating (i.e. reduction of fertility and mortality) as
improvements in socioeconomic conditions only serve to
intensify these processes [39].
Evolutionary theorists have had a difficult time recon-
ciling the demographic transition within an adaptive life
history model [33]. Why does increased socioeconomic
development result in a failure to increase reproductive
success? A failure to identify an adaptive cause is a major
problem since its universality suggests that these trends can
only be explained in deeper evolutionary terms. Proposed
explanations have included maladaptation to contraceptive
technologies [40], fragmentation of kin networks [41],
emerging roles of social prestige in labour market [42], and
rising investment costs in producing socially and economi-
cally competitive offspring [33]. The best life history
framework is definitely provided by the idea that industri-
alization makes it increasingly energetically costly to invest
valuable time and energy in current reproduction. However,
this framework cannot address the relatively new phe-
nomenon of adults en masse opting not to reproduce. Ar-
guably, delaying biological reproduction completely and
effectively removing oneself from reproductive gene
pool is a novel behavioural phenomenon for an individual
organism with reproductive capability. This makes modern
societies life history trajectory increasingly bizarre and
difficult to explain when conceptualized within a traditional
life history framework.
INTO THE FUTURE
I propose that our changing life history pattern is best
explained as the fourth evolutionary exaggeration of the
characteristic primate life history pattern towards later sexual
maturity and longer life expectancy. This is fundamentally
being driven by the same processes as previous primate life
history transitions, namely selection for individuals with
ever-greater levels of knowledge, skills, and social coordina-
tion, which require ever-longer developmental periods dedi-
cated to learning. However, the major difference between
this transition and previous transitions is that this transition’s
dominant evolutionary pathway is cultural, as opposed to
biological. As a result, the reduction of biological fertility is
adaptive for the continued acceleration of cultural reproduc-
tion. The on-going selection for cultural reproduction comes
at the direct expense of biological reproduction. If true, this
could suggest that cultural evolution is in the early stages of
modelling and replacing the biological evolutionary process.
Such a development would mark a new evolutionary period
in the history of life as all of previous life history was driven
by variant chemical structures harvesting energy to create
more complex replicates of similar forms (as opposed to
variant cultural structures).
Evolutionary scientists have long recognized that the
cultural evolutionary process shares many non-arbitrary par-
allels with biological evolutionary processes [43], and that
these cultural evolutionary processes are uniquely manifest
in the human species [44, 45]. Experiments show that cumu-
lative cultural evolution is not only unique but can also result
in adaptive complexity in behaviour and can also produce
convergence in behaviour [46, 47]. Before the emergence of
humans biological evolution was the only way this type of
adaptive complexity could emerge. With cultural evolution
as a new mechanism for complexity construction the entire
evolutionary process is more potent and can operate much
more quickly [47]. Furthermore, cumulative cultural evolu-
tion consumes all of human individual and collective exis-
tence. The human life is one spent first learning the knowl-
edge, inventions, and achievements of previous generations,
and then secondly, building upon them (i.e. ratcheting "up"
the complexity) [45]. In the modern world, all individual and
collective economic success is dependent on our cultural and
technological complexity, the mechanism for which is our
ability to understand and make use of imparted knowledge
and artifacts [46]. From this perspective it does not seem
unreasonable to suggest that one evolutionary process (i.e.
culture) is growing more dominant than another (i.e, biol-
ogy). To envision these as evolutionary pathways, I would
propose that one evolutionary pathway is "biochemical" and
one is "technocultural".
Considerable evidence supports the assertion that cul-
tural replication is now in the early stages of superseding
biological replication as the dominant form of complexity
construction. In the modern world we find ourselves in an
ever-more challenging cultural environment that is acceler-
Human Evolution, Life History Theory Current Aging Science, 2014, Vol. 7, No. 1 21
ating pressures for the acquisition of ever-more cultural
information. Of course, the pressure to learn ever-more
cultural information has been a feature of our species since
our emergence. This process has operated via the mecha-
nism of the cultural ratchet (see: [45]), but I argue that the
selection for this process is now superseding biological
processes. The pressures to learn ever-more advanced cul-
tural information are most notably manifesting in the pres-
sure for ever-more people requiring ever-more advanced
forms of education. We should expect this trend to con-
tinue, and in fact accelerate quite quickly throughout the
21st century along with the continued diffusion and expo-
nential improvement in information and communication
technologies (ICT). Specifically the emergence of ever-
more advanced robotics and artificial intelligence systems
should replace the need for humans to do low-skill, low-
education jobs. The removal of low-skill, low-education
jobs should increase individual opportunity to explore cul-
tural reproduction-as-vocation (e.g., music, art, science,
engineering, etc.). Artificial intelligence systems becoming
embedded in operating systems and apps should also in-
crease our ability to do ever more complex jobs that require
ever-more advanced degrees. Finally, wearable computing,
and in a decade or two brain-interface devices, should exert
a strong pressure on people to acquire more and more cul-
tural information to remain socially and economically
competitive (for detailed information on a potential evolu-
tionary pathway see: [48]).
Evidence that cultural replication is now superseding
biological replication can also be found in two other phe-
nomena emerging in their early stages: increasing lif e
expectancy and increasing number of people in developed
countries opting not to biologically reproduce at all. In
our evolutionary past, increasing life expectancy co-
evolved with increasing brain size [12]. In the modern
world our absolute brain size is not expanding but the
amount of information our brain is required to accumulate
in order to compete is certainly increasing (again, see:
[48]). Furthermore, as many computer scientists, philoso-
phers, and futurists have pointed out, we are actually ex-
tending the information our neocortex collects into ever-
more sophisticated computers. This type of "mind
outsourcing" is an idea that works well with the extended
mind hypothesis, which asserts that our species has al-
ways extended m ind into external mediums since the
emergence of verbal language (see: [49]). However, the
digital substrate is something new. Many suspect that our
exponential outsourcing of mind-to-computation will re-
sult in our eventually connecting our minds to the "cloud"
and enhancing the processing power of our neocortex via
this mechanism (se e: [50, 51]).
Undoubtedly this process is a cultural evolutionary proc-
ess leading to increased brain capacity, and not a biological
evolutionary process. If the past is any indication we should
expect our life expectancy to increase along with this type of
brain expansion. The mechanisms to achieve this are already
emergent and practical application of them should be near-
term realities from the continued advance of biomedicine
and genetics [52, 53]. Such advances are likely to include the
practical application of replaceable stem cell organs, the
complete prevention of degenerative diseases, and a funda-
mental understanding of reversible genetic causes of aging.
Currently, stem cell organ replacement is likely to reach a
practical application stage in 10-20 years, and fundamental
reversible causes of aging have already been identified (see:
[54, 55]). Therefore, it is reasonable to suggest that the be-
ginnings of radical life extension have already started. If that
thesis is not convincing, it is undoubtedly true that the cul-
tural war on aging has already started, as many ma-
jor biomedical companies, including a new biomedical
branch of Google (e.g. [56], are investing heavily in research
related to identifying the reversible causes of aging (for more
see: [53]).
Finally, another sign that cultural reproduction is tak-
ing the place of biological reproduction is the simple fact
that many individuals in the developed world are, for the
first time, making the culturally informed decision to not
reproduce biologically. This phenomenon is helping drive
the trend towards a developed world that is already below
replacem ent fertility level (e.g. [39, 57, 58]) (Table 3).
This means that we are currently at a crucial time period,
as it appears we are reaching the "tipping point" where
biological reproduction is becoming "too costly" to justify
in the face of rising pressure for ever-greater cultural re-
production, as well as the increased opportunity for cul-
tural reproduction-as-vocation. Most experts today do not
factor in these pressures that w ill likely lead to ever fur-
ther reduction of biological reproduction. However, lead-
ing reports still suspect that nearly ha lf of the world's
population is currently residing in countries at or below
replacem ent level ferti lity [57]. Many other rapidly devel-
oping regions of the world should approach these fertility
levels within mere decades [57] and the entire world
should have completed the transition to below replace-
ment level fertility by 2050 [37].
Surprisingly, these hypothesized trends (i.e. increased
pressure to acquire ever-more cultural information, increas-
ing life expectancy co-evolution with increased brain ca-
pacity, and increased autonomous individual decisions to
avoid biological reproduction) are not at odds with Life
History Theory (LHT). As stated above, traditional LHT
conceptualized growth and maintenance in solely biological
terms (e.g. somatic cell replacement and maintenance) (e.g.
[24]). As a result traditional LHT presents a "sex versus
soma" framework (e.g. [19]). However, for organisms like
humans, growth and maintenance can also be achieved
through cultural learning via the brain [23]. So within this
LHT framework I am proposing that an emerging fourth
primate life history transition is in the process of reducing
energy dedicated to current biological reproduction indefi-
nitely. This is occurring in favour of allocating en-
ergy towards ever-more advanced culturally mediated
growth and maintenance through learning via our enlarged
(and perhaps soon-to-be-dramatically enlarged) brains. The
mechanisms to realize this transition, as described above,
are already emergent. All selection for this process is un-
doubtedly being driven by cultural evolution as opposed to
biological evolution, which may suggest that a new evolu-
tionary process is soon to predominant the biological evo-
lutionary process. Complexity would be directed by mind.
22 Current Aging Science, 2014, Vol. 7, No. 1 Cadell Last
I predict that the full realization of this life history transi-
tion should occur before 2050, which suggests that this the-
ory could be in some way connected to the hypothesized
metasystem transition commonly referred to as Global Brain
(see: [48, 59-61]). In order to take this 21st century future
seriously we need only assume that the pressures of the
modern developed world hold and accelerate globally. First
and foremost, the pressures for the acquisition of more ad-
vanced cultural information must accelerate as a result of
advanced ICT. This will continue to force an extension of a
widespread postponement of biological reproduction. Sec-
ondly, continued advances in our understanding of aging and
degenerative diseases must accelerate dramatically, allowing
us to radically extend life expectancy and possibly usher us
into a post-aging world. This will remove the evolutionary
imperative to create complexity through biological reproduc-
tion, as delaying current reproduction would always be pre-
ferred in favour of dedication of energy towards culturally-
mediated growth and maintenance.
In the future, further research into the specific causal
mechanisms driving a potential complete end to biological
reproduction is needed. At the moment the exact mecha-
nisms are unknown. However, one possible causal mecha-
nism explaining how culture, technology, and information
can impact the biological change in reproduction has been
discussed by Kyriazis in this issue.
However, although the extrapolation of current trends
and framing these trends within well-tested evolutionary
frameworks is a useful methodological tool for explaining
our likely future, we cannot be 100% certain that this is our
future. Fundamentally, this life history future is dependent
on continued system-level socioeconomic development as
supported by the current industrialized energy regime, as
well as a smooth transition to a new post-industrial energy
regime before 2050. In short, this life history future is fun-
damentally dependent on abundant energy globally. This is
not an outrageous assumption (see: [62, 63]). However, if
current trends are significantly ruptured by large socioeco-
nomic processes related to a collapse of our current energy
regime, and/or a failure to establish a post-industrial energy
regime, we should not expect the life history trajectory out-
lined above.
CONCLUSION
Human life history throughout our species evolution can
be thought of as one long trend towards delayed sexual
maturation and biological reproduction (i.e. from “living fast
and dying young” to “living slow and dying old”).
Due to the evolution (and consequent complete de-
pendence) on our large brains, human life h istory is orga-
nized around the acquisition of cultural information. This
has always required inordinate amounts of time and en-
ergy dedicated to growth. Over the past 200-250 years,
humans in the industrialized world have experienced a
significant rupture to this pattern. This rupture is best ex-
plained as yet another primate extension of pre-
reproductive years and extension of life span. Fundamen-
tally, this transition is only different from previous transi-
tions in that the dominant evolutionary processes driving
this exaggerated life history is cultural. This explanation
adequately addresses what previous demographic transi-
tion life history explanations fail to address, especially in
regard to autonomous adult humans opting to not repro-
duce biologically at all.
In the case that my aforementioned assumptions prove
incorrect, this analysis should prove useful for the impor-
tant reason that you can make a fairly reliable prediction
for biological reproduction given radical life extension
(RLE). If RLE is not achieved before 2050, but instead at
some later date, 100, 150, or 500 years from now, this will
likely coincide with the indefinite postponement of current
biological reproduction in favour of current cultural repro-
duction. Therefore, any popular or political opposition to
the practical application of RLE breakthroughs on the basis
that they would lead to catastrophic overpopulation issues,
are almost definitely unfounded. Also, any scientists cur-
rently involved in research related to RLE should not fear
that their breakthroughs will lead to major population prob-
lems that will need to be solved at some future period of
time.
CONFLICT OF INTEREST
The authors confirm that this article content has no con-
flict of interest.
ACKNOWLEDGEMENTS
I would like to thank Marios Kyriazis, Clement Vidal,
Francis Heylighen, as well as all members of the Global
Brain Institute (GBI), and the Evolution, Complexity, and
Cognition (ECCO) groups, for helpful feedback and discus-
sion. I would also like to thank the anonymous reviewers for
improving the clarity and structure of the article.
PATIENT’S CONSENT
Declared None.
Table 3. Global Fertility Ra te (2014 est.) [64]
Replacement Fertility Rate (2.1)
# of Countries
Examples
Countries > 2.1
108/224
Niger, Philippines, Belize, Yemen
Countries < 2.1
116/224
France, Norway, Australia, Canada
Countries < 1.5
32/224
Germany, Japan, Italy, South Korea
Countries < 1.0
2/224
Macau, Singapore
!
Human Evolution, Life History Theory Current Aging Science, 2014, Vol. 7, No. 1 23
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Received: January 13, 2014 Revised: April 18, 2014 Accepted: May 14, 2014
