Sexual selection, carnivory & life history evolution in ...

Sexual selection, carnivory & life history evolution in the human radiation

W.D. Hamilton

and subsequently

Kristen HawkesAnthropology

University of [email protected]

150th anniversary of Descent of Man & Selection in Relation to Sex

DySoC & HuBCEGHuman Social systems & Evolution

Hominidae

subfamily

tribe

family

plus things learned since

From Descent:Vol I, Chap V pp 162-3

“When two tribes of primeval man, living in the same country, came into competition, if the one tribe included ...a greater number of courageous, sympathetic, & faithful members,...this tribe would without doubt succeed best and conquer the other.

...but in the course of time it would, judging from all past history, be in its turn overcome by some other and still more highly endowed tribe. Thus the social and moral qualities would tend slowly to advance and be diffused throughout the world.”

... He who was ready to sacrifice his life...rather than betray his comrades, would often leave no offspring to inherit his noble nature. The bravest men, who were always willing to come to the front in war, and who freely risked their lives for others, would on an average perish in larger number than other men....


Therefore it seems scarcely possible ...that the number of men gifted with such virtues, or that the standard of their excellence, could be increased through natural selection, that is, by the survival of the fittest.”

“But it may be asked, how…did a large number of members first become endowed with these social & moral qualities, and how was the standard of excellence raised?

But there is another and much more powerful stimulus to the development of the social virtues, namely, the praise and the blame of our fellow-men. The love of approbation and the dread of infamy, as well as the bestowal of praise or blame, ... [which] no doubt was originally acquired, like all the other social instincts, through natural selection”


“[Yet]we can trace some of the probable steps.... In the first place ...each man would soon learn from experience that if he aided his fellow-men, he would commonly receive aid in return.

“…individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind … any variation in the least degree injurious would be rigidly destroyed. This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection.

…what I call Sexual Selection…depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring.”

From the Origin:

“In the case of animals and plants with separated sexes, it is of course obvious that two individuals must

always unite for each birth”The Fisher Condition:

“...consider the aggregate of an entire generation…each sex must supply half the ancestry of all future generations of the species” So:

1) diploid offspring sex ratios normally 50:50 (& why sometimes not) 2) mating sex ratios affect reproductive strategies

Modern Synthesis:Natural Selection

plusMendelian Inheritance

From the Origin:

Initially: grandmother hypothesis forpostmenopausal longevity,

later maturity, shorter birth intervalsVS other living hominids:

Now see longevity our bigger brains early weaning our social appetites

sexual selection consequencesmale-mate competition

pair bondingarchaeological record of carnivory

W.D. Hamilton

Hominidae

subfamily

tribe

family

Archaeological support for the hunting hypothesis…?

Scientific American

Lewis Binford

Tools vs JawsTransported vs Near kill

Scavenging from carnivores vs Hunting

“…consumption was at the place of procurement”

“…no evidence supporting the argument that the hominids at Olduvai Gorge were hunting”

“No evidence for basecamps exists” 1981

Hadza foragersnorthern Tanzania

Utah/UCLA Hadza Project

Key collaboratorsJF O’Connell, Utah

NG Blurton Jones, UCLA

Butchering stands

Residential bases

O’Connell et al. 1992 J Arch Sci

where Hadza never camp

3rd kind of site: seasonal hunting blinds

near perennial water points multiple carcass

butchering stands

From ~ 10 m2

~ 450 bone fragments> 11 individual animals

KD Lupo 1993

JF O’Connell, K Hawkes, KD Lupo, NG Blurton Jones 2002 J Hum Evol

Assemblage composition AND ecological context like Hadza seasonal hunting blinds: perennial springs & drainages: dry season aggregations of ungulates & carnivore predators

As others have noted “a sharp increase in [evidence of hominin exploitation of large animal carcasses] after 1·9 Ma ...” O’Connell et al. 2002:857

Datemya

1.21.61.61.761.4

Utah/UCLA Hadza Project Hunting & aggressive scavenging

with powerful bows & arrowsKey collaboratorsJF O’Connell, Utah


O’Connell, Hawkes, Blurton Jones1988 Curr Anthropol

Hawkes1993 Curr Anthropol2016 J Anthrop Archaeol

Hawkes, O’Connell, Blurton Jones1991 Phil Trans Roy Soc2001 Curr Anthropol2001 Evol Hum Beh2014 Hum Nat2018 Am J Phys Anthropol

Hawkes & Bliege Bird2002 Evol Anthropol

O’Connell et al. 2002 J Hum Evol

Take big carcasses away from

large carnivores

Utah/UCLA Hadza Project Hunting & aggressive scavenging

with powerful bows & arrowsKey collaboratorsJF O’Connell, Utah


Most shares claimed by others

BONANZA FOR ALL

Capture chance03.4%

hunter-day

O’Connell, Hawkes, Blurton Jones1988 Curr Anthropol

Hawkes1993 Curr Anthropol2016 J Anthrop Archaeol

Hawkes, O’Connell, Blurton Jones1991 Phil Trans Roy Soc2001 Curr Anthropol2001 Evol Hum Beh2014 Hum Nat2018 Am J Phys Anthropol

Hawkes & Bliege Bird2002 Evol Anthropol

O’Connell et al. 2002 J Hum Evol

Utah/UCLA Hadza Project

children too smallfor year ‘round stapleso depend on mom

until she has a newborn

Key collaboratorsJF O’Connell, Utah


in CONTRAST to our great ape cousins:

Blurton Jones, Hawkes & O’Connell 1989 in Comparative SocioecologyHawkes, O’Connell & Blurton Jones 1989 in Comparative SocioecologyHawkes, O’Connell & Blurton Jones 1995 Current AnthropologyHawkes, O’Connell & Blurton Jones 1997 Current AnthropologyRobson, van Schaik & Hawkes 2006 in The Evolution of Human Life HistoryBlurton Jones 2016 Demography & Evolutionary Ecology of Hadza Hunter-GatherersHawkes, O’Connell & Blurton Jones 2018 Am J Phys Anthropol

Eating every day?

Then depend on grandmothers



1. Small youngsters can’t 2. Adults reliable DAILY rates3. Higher in batches 4. Older women add to batches5. Subsidize dependents: moms have next

baby sooner

Savanna foods are key

0 1 2 3 4 5 6 7 8 9

Time spent

109876 43 210

Nut

ritio

n (e

nerg

y) g

aine

d gaincurve



0% 5% 10% 15% 20% 25%

0 - 4

5 - 9

10-14

15 - 19

20 - 24

25 - 29

30 - 34

35 - 39

40 - 44

45 - 49

50 - 55

55 - 59

60 - 64

65 - 69

70 - 74

75 - 79

80 - 84

0% 5% 10% 15% 20% 25%

0 - 4

5 - 9

10-14

15 - 19

20 - 24

25 - 29

30 - 34

35 - 39

40 - 44

45 - 49

50 - 55

55 - 59

60 - 64

65 - 69

70 - 74

75 - 79

80 - 84

Age class Age class

5 wild chimpanzee sites: Hill et al. 2001 J Hum Ev

% of female population

Hadza: Blurton Jones 2016 Demography & EvolutionaryEcology of Hadza Hunter-gatherers

% of female population

Chimpanzees Humans

1/M

EL Charnov 1991, 1993, etc.Life history variation in female mammals

Great Apes

Humans

a

Adult lifespans drive the variationApproximately “invariant”

aM

TAXON aM

ORANGUTANS 0.46GORILLAS 0.45

CHIMPANZEES 0.46HUMANS 0.44

Hawkes, O’Connell, Blurton Jones, Alvarez, Charnov 1998 PNAS

Great Apes

Humans


Age at maturity X adult mortality rate

a

1/M


aM


TAXON aM





Charnov & Berrigan 1993 Evol Anthropol


aM


TAXON aM







aM & ab



TAXON aM ab

ORANGUTANS 0.46 0.52GORILLAS 0.45 0.79

CHIMPANZEES 0.46 0.70HUMANS 0.44 2.05


Age at maturity X baby production rate



aM & ab

PS Kim, JE Coxworth, K Hawkes 2012 Proc Roy Soc BPS Kim, JS McQueen, JE Coxworth, K Hawkes 2014 J Theor Biol

PS Kim, JS McQueen & K Hawkes 2019 J Theor Biol

Peter Kim’s 2-sex agent-based model simulates grandmother

effects on great ape-like longevity

JE Coxworth, Kim PS, McQueen JS, Hawkes K 2015 PNAS

Model valuesFertile adults

M/F & % Males

M/F %M

w/outgrams

0.77 44%

withgrams

1.56 61%

Adult Sex RatioFertile adults Male/ Female

Track sex ratios in fertile ages as longevity evolves

Peter Kim’s 2-sex agent-based model simulates grandmother

effects on great ape-like longevity FEMALESMALES

12% 10% 8% 6% 4% 2% 0%

Fertile agesbrackets

Model valuesFertile adults

M/F & % Males

M/F %M

w/outgrams

0.77 44%

withgrams

1.56 61%

Chimpanzees Fertile adultsM/F

Fertile adults %M

5 sites 0.47 32Kanyawara 0.70 41

Avg = 0.59 Avg = 37% Hunter-

gatherersFertile adults

M/FFertile adults

%M!Kung 1.46 59Ache 1.87 62Hiwi 1.62 62

Hadza 1.60 62Avg = 1.64 Avg = 61%

JE Coxworth, Kim PS, McQueen JS, Hawkes K 2015 PNAS


FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


R Schacht & AV Bell 2016 Scientific Reports

The Fisher conditionMale-biased mating sex ratios

favor mate guardingFEMALESMALES

12% 10% 8% 6% 4% 2% 0%


Model valuesSex ratio of Fertile Adults

M/F & % Males

Coxworth, Kim, McQueen, Hawkes 2015 PNAS

M/F %M

w/outgrams

0.77 37%

withgrams

1.56 61%

R Schacht & AV Bell 2016 Scientific Reports

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%



M/F & % Males

M/F %M

w/outgrams

0.77 37%

withgrams

1.56 61%

Guarder’s chance of losing paternities

Sex ratio when guarding takes over


SL Loo, K Hawkes, PS Kim 2017 Phil Trans Roy Soc B

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%



M/F & % Males

M/F %M

w/outgrams

0.77 37%

withgrams

1.56 61%


SL Loo, D Rose, MD Weight, K Hawkes, PS Kim 2020 Bull Math Biol

Benefit supplied to all

a Reputational increment on paternity chances to suppliers

Paternal caringstable

Large game scavenging& hunting stable

Large game scavenging& hunting stable

Paternal caringstable

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


322 observation days: lions & hyenas still on 18 of 19 large carcasses

when Hadza drove them off w/ bows & arrows

[tech around only Upper Pleistocene]O’Connell et al. 2002 JHE

Hill & Hurtado 1996 Aché Life HistoryBlurton Jones 2016 Demography & Evolutionary Ecology

of Hadza Hunter-gatherers

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


Hunting reputations matter

“The price of entering the dog-eat-dog world of the carnivore guild was undoubtedly high, and therefore,

the rewards must have been substantial” p 117

Blaire Van Valkenburgh2001 In Meat-Eating & Human Evolution Stanford, & Bunn Eds.

after ~ 1.9 mya archaeology records dangerous contests with large carnivores

O’Connell & Hawkes (in review) Evolution of human life history: subsistence, mating sex ratios, carnivore competition

East African Plio-Pleistocene Large Carnivore Guild

Van Valkenburg 2001 p 110

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


When greater longevity biased fertile sex ratio toward males Deference of paternity competitors to proprietary mating claims

made intimidating dangerous carnivores worth the risks

The Fisher condition

O’Connell & Hawkes (in review) Evolution of human life history: subsistence, mating sex ratios, carnivore competition


FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


J Collier 1988 Marriage & Inequality in Classless Societies: “...relations between spouses are best understood in the context of relations between men…men must assert claims to womenin competition with other men”

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


The Fisher condition


[that] weapons of offence and the means of defence possessed by the males - their courage and pugnacity -.... are the result of sexual …selection is clear, as unarmed...males would succeed equally well in the battle

for life and in leaving a numerous progeny, if better endowed males were not present.”

From Descent:Part II, Chap VIII pp 256-8

“through natural selection ...those individuals which generated or nourished their offspring best, would leave, cæteris paribus, the greatest number to inherit their superiority... [In other] cases sexual selection must have come into action, ...[not making males] better fitted to survive in the struggle for existence, but from [giving them] an advantage over other males, ...It was the importance of this distinction which led me to designate this form of selection as sexual selection....

FEMALESMALES

12% 10% 8% 6% 4% 2% 0%


Our grandmothering life history:Finlay & Uchiyama 2017 In Evolution of Nervous SystemsHawkes & Finlay 2018 Physiol BehavHawkes 2020 Phil Trans Roy Soc

Hrdy 1999 Mother Nature2009 Mothers & Others

Hawkes 2014 Hum NatHawkes 2020 Phil Trans Roy Soc

2020 Integr Comp Biol

1. longevity brain size

2. early weaning infant sociality: priority to relationships

3. male biased mating sex ratios4. mate guarding 5. then dangerous contests with big carnivores

displaying “courage & pugnacity” earn others’ deference: if so, early archaeology is a record of male mating competition

Finlay & Uchiyama 2017 In Evolution of Nervous SystemsHawkes & Finlay 2018 Physiol BehavHawkes 2020 Phil Trans Roy Soc

Hrdy 1999 Mother Nature2009 Mothers & Others

Hawkes 2014 Hum NatHawkes 2020 Phil Trans Roy Soc

2020 Integr Comp Biol

1. longevity brain size

2. early weaning infant sociality: priority to relationships

3. male biased mating sex ratios4. mate guarding 5. then dangerous contests with big carnivores

displaying “courage & pugnacity” earn others’ deference: if so, early archaeology is a record of male mating competition

Questions, Concerns?

Sexual selection, carnivory & life history evolution in ...

Documents

Transcript of Sexual selection, carnivory & life history evolution in ...