This document discusses human evolution and life history theory, suggesting a potential fourth transition is emerging towards biological reproduction being replaced by cultural reproduction. It outlines three previous primate transitions from prosimians to monkeys to apes to humans, characterized by later sexual maturity and longer lifespans. This enabled increased brain size and parental care. The author argues modern trends towards very low fertility rates and high life expectancy represent a new transition fueled by cultural learning outweighing biological needs. This could lead to radical life extension and "idea sex" driving change over biological reproduction by 2050.

1. Human Evolution, Life History Theory,
and the End of Biological Reproduction
Cadell Last (M.Sc.)
Evolutionary Anthropologist
Global Brain Institute (GBI)

2. “Weak fertility and rising life expectancy are
driving a unique and relentless aging
structure never seen before.”
- George Magnus (economist)

3. Overview
• Three major primate life history transitions
– Prosimian->Monkey / Monkey -> Apes / Apes -> Humans
• Life History Theory
– Energy budget: Growth, maintenance & reproduction
• Fourth transition emerging? (1750-2050)
• A transition towards a new evolution?
– Biological reproduction -> Cultural reproduction

4. Transitioning from: “Live Fast, Die Young”
• Primate trend over 60 million years:
– From prosimians to humans
– Later sexual maturity / Longer life expectancy
• The Hominoids
– Chimpanzees/Bonobos
– Gorillas
– Orangutans
• Increased parental care and social learning with
increased brain size

5. Great Ape and Human Life Histories
Species Sexual Maturity Life Expectancy
Orangutans (Pongo) 9-10 50-55
Gorillas (Gorilla) 8-9 45-50
Chimpanzees (Pan) 8-9 45-50
Human (Homo) 18-20 75-85

6. “It takes a village to raise a child”
• Life history transition in humans required:
– Parental support by post-reproductive individuals
– Extensive male parental support
• Which led to:
– Menopause
– Concealed ovulation
– Continued non-reproductive sexual activity

7. Brain Explosion
• Human life history co-evolved with brain
expansion (specifically neocortex)
– Life expectancy/brain size correlated in mammals
• Fossil data on:
– Cranium size
– Skeletal ontogeny
– Dental maturation

8. One Transition; Multiple Waves
Species Time (Mya) Cranial
Capacity (cc)
Est. sexual
maturity
Est. 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

9. Life History Theory (LHT)
• Life History Theory: explains “trade-offs”
between energy (e) expenditure on biological:
– Growth (g), maintenance (m), reproduction (r)
• Finite energy (e) creates evolutionary strategy
between current/future reproduction:
– (e) investment (g)/(m) chances of future (r)
– (e) investment (r) chances of future (r)

10. LHT in Human Evolution
• All unique human LH patterns emerged as by
product of growing neocortex
– i.e., menopause, male-female co-parenting, etc.
• Neocortex increase fuelled w/ cooked meat
– Meat acquired via large-scale hunting w/ technology
• Dependence on cultural & technological
processes for energy required increased
investment in learning: (e = g/m > r)

11. Trading Current (R) for Cultural Knowledge
“Childhood became an intellectual and social stage of
development requiring increasingly large amounts of time
and energy at the expense of current reproduction.”

12. Modern Times
• Agricultural age: little-to-no life history change
– No extra learning required
– No extra energy for 99.9% of people
• Industrial age: demographic transition
– Pressures for extra cultural learning emerge
– Reduction of fertility (2) and mortality (80)
• Demographic transition
– Culturally universal w/ industrialization
– Transition likely to be completed globally by 2050
– Intensifying further in developed countries

15. Fertility Rate Declining
• # Countries Below Replacement Level Fertility
(<2.1):
– According to U.N. (72/195) / CIA World Factbook
(115/224) / World Bank (79/197)
• Many countries at or below 1.5
– e.g., South Korea, Japan, Italy, Spain, Germany
• Cyprus (1.61 / 1.45 / 1.47)
• Macau, Singapore, Hong Kong below 1.0

16. A New Life History Theory Explanation
• Biocultural Life History
– (g)/(m)/(r) is cultural as well as biological
• Investment is cultural learning (g/m) as well as
cultural (r) delaying current biological (r)
• Culture starting to model and outcompete
biology?

17. Cultural Evolution Rises
• Parallels between biological and cultural
evolution
• Cumulative cultural evolution consumes the
human life (g)/(m)/(r)
• All individual and collective economic success
dependent on culture
• Life long cultural reproduction as vocation (r)

18. Fourth Primate Life History Transition?
• Emerging *Early* Trends:
– Permanently delayed biological reproduction
– Increasing life expectancy
• Brain extension: Neocortex to the cloud?
– Outsourcing symbol system to computation
• Tipping point: radical life extension (2050?)
– Cultural reproduction > biological reproduction
– Complexity directed by mind

19. Stated Clearly…
• A future of increasing biology-technology merger
in the human – is a future with significantly
reduced biological (r) in favour of cultural (r)
• “Idea sex” as new primary mechanism for
evolutionary change
• Transitions:
– Prosimian -> Monkey
– Monkey -> Apes
– Apes -> Humans
– Humans -> “Transhumans”

20. The Human System: A Caveat
• Demographic transition started with Industrial
Revolution, but…
– Won’t be completed until industrial transition is complete
• LH is always dependent on energy budgets
– Future of LH dependent on abundant energy
– Fusion (solar/nuclear fusion)
• An abundant energy future enables everyone to
participate in cultural reproduction as vocation

21. “Were individuals able to expend unlimited energy at
no cost, in principle they could evolve to grow and
develop so rapidly they could begin reproducing
immediately after birth, massively producing
offspring, and preserve themselves such that they
never age. In biological reality, however, individuals
must live within finite energy “budgets”.”
- Kaplan & Gangestad (2004)
But what about “in cultural reality”?

22. Thank you for your time!
Now for the idea sex…
I mean discussion!