just for Njosh
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section3_fatherhood.docx1/21/17
1/21/17
1/21/17
What Makes Humans Special
?
Which traits or characteristics are uniquely human
?
Why did they evolve and how do they help us to
understand human
families and fathering?
Humans compared to other primates: What makes primates special?
Relative to other mammalian orders, the primate order is
slow growing
slow reproducing
long lived
large brained
Humans at extreme of primate continuum
Package of traits makes humans unique
6 Distinctive
Human Characteristics
1. Life span
2. Juvenile dependence
3. Multigenerational resource flows
4. Concealed ovulation/monogamous bond
5. Male provisioning
6. Brain size and cognitive competencies
There are others (e.g., bipedal, language) but these are less relevant to biosocial development in families
Distinctive Human Characteristics
1. Lifespan:
Longest living terrestrial mammal
Oldest human– French woman 122 yrs
Age at maturity
(
time from weaning to first birth
)
Average adult lifespan
Lifespan
Long Lifespan
Implications
:
•
Long
-
lived animals
have corresponding
long life stages. In
long
-
lived humans,
there is a long pre
-
adult phase where
offspring are still
dependent on parents.
•
Long post
-
adult phase
enables long
-
term
relationships between
parents and grown
offspring (and grand
-
children)
Distinctive
Human Characteristics
2
. Juvenile dependence
:
Extended period of care
Results in families with multiple
dependent children of different
ages
Long Juvenile
Short infancy
a
nd IBI
Long juvenile
(
subadult
)
Implications
:
•
Long dependency
(
pre
-
adult)
Mortality
Rates of child survivorship
Hunter
-
gatherer societies:
Age
-
specific mortality profile:
First 5 years: Very High
Juvenile years: Low
After age 15: Very low
60
s and 70s: Increases again
Human children are a good long
-
term bet
Low
mortality
(
after they survive infancy) favors
offspring
quality
over quantity.
---
About
60
% survive to reproductive
age
---
Distinctive Human Characteristics
.
3. Multigenerational resource flows:
· Post-reproductive individuals support reproduction of other kin
· Resource flow old-> young
Long
Post
-
Reproduction
Only a very few
number of species
have a very long post
-
reproductive life.
Hi proportion of
post
-
repro remain
alive
Humans
Pilot whales
Low proportion of post
repro remain alive in other
primates
-
only a few years
.
Multigenerational resource flows:
Post
-
reproductive individuals support reproduction of
other kin
Resource flow old
-
>
young (positive net contribution
)
Distinctive
Human Characteristics
4
. Concealed Ovulation/monogamous bond
Concealed ovulation
Distinctive Human Characteristics
.
5. Male provisioning:
· Male support of reproduction through provisioning females and offspring
· Unusually short infancy
period (lactation) leads to short interval between birth and multiple dependent offspring
Male Provisioning
Short infancy
a
nd IBI
Long juvenile
(
subadult
)
Males provide
critical support &
food
to mothers
and offspring.
This likely enabled
mothers to shorten
IBI and make it
possible to feed
multiple offspring
at once
The role of men in food-getting
Unlike most other mammals,
men
in
foraging societies (
hunter
-
gatherers)
provide the majority of the energy
necessary to support reproduction
After subtracting own consumption
Women supply average of 3% of
calories to offspring
Men provide remaining 97%
Men are hunting specialists.
Why not women? Largely
incompatible with pregnancy,
lactation, and carrying dependent
offspring
Food Contribution by Men
Figure 12.06
Food Contribution by Men
3
well
-
studied modern foraging groups
Aché
, the
Hadza
,
Hiwi
Figure 12.08
Food Contribution by Men
9
modern foraging groups
F
i
g
u
r
e
1
2
.
0
7
b
Food Contribution by
Women
F
i
g
u
r
e
1
2
.
0
7
a
Food Contribution by Men
Foraging and sexual division of labor
· BOTH contribute calories
· Complementarity between male and female roles:
· Males- hunting and fighting
· Females- gathering and nurturing
The human foraging strategy (particularly hunting) promotes:
1. Cooperation between men and women
2. Male parental investment (food, care...)
Distinctive Human Characteristics
6. Brain size and cognitive competencies
Human
Chimpanzee
Macaque
humans
•
Generally primates have larger than expected brains
•
Human brain is even larger than all the primates
The importance of
Learning-Intensive
Foraging Strategies
· Unique human characteristics coevolved with extreme human commitment to learning-intensive foraging strategies
· Dietary shift: to high quality, nutrient-dense, difficult to get
· Humans vs. Chimpanzees: men 5x more productive (calories)
Learning-Intensive
Foraging Strategies
· Abilities needed to exploit high-quality resources (knowledge, skill, coordination, strength)
· Attainment of these abilities requires time and significant commitment to development.
· Extended learning phase and support
· Productivity during childhood vs. adulthood
Net food production:
· Negative until age 14
· Peaks between 35-45
Socio-Cognitive Competencies
For cooperation and competition
· Within-group (mating, status, cooperative hunting, cooperative child rearing)
· Between-group (cooperation for warfare)
6
Distinctive
Human Characteristics
1.
Life span
2.
Juvenile dependence
3.
Multigenerational resource flows
4.
Concealed ovulation/monogamous bond
5.
Male provisioning
6.
Brain size and cognitive competencies
There are others (e.g., bipedal, language)
but these are less relevant to biosocial
development
Distinctive Human Characteristics
Why did this package of traits
evolve
—
how did it promote
survival and reproduction (fitness)
in our ancestors?
What were the responsible factors
or circumstances?
Is there a theory to tie this together?
Punch Line
Families have evolved because they provide socio-ecological adaptive benefits (i.e., survival and reproduction).
Our biology and culture has evolved to support the formation and maintenance of social bonds in families and kin-based groups.
Discussion
Week 2b
· In lecture we discussed a suite of 6 traits that makes humans distinct among mammals
· Name 1 of these 6 traits AND how it is relevant to males as fathers in families.
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