Re: Culture may depend on numbers; warfare and altruism

On Jun 14, 11:31 pm, Dave Smith <da...@xxxxxxxxxxxxxxxxxxxxxx> wrote:
On 14 June, 16:46, Gary <LanceG...@xxxxxxxxx> wrote:



On Jun 13, 1:30 am, Dave Smith <da...@xxxxxxxxxxxxxxxxxxxxxx> wrote:

On 12 June, 23:50, Dave Smith <da...@xxxxxxxxxxxxxxxxxxxxxx> wrote:

http://www.santafe.edu/~bowles/

Sorry, the above link doesn't seem to lead directly to the intended
article from New Scientist:

Ancient warfare: Fighting for the greater good
 04 June 2009 by Ewen Callaway

War, what is it good for? A lot, it could turn out.

Lethal warfare drove the evolution of altruistic behaviour among
ancient humans, claims a new study based on archaeological records and
mathematical simulations.

If correct, the new model solves a long-standing puzzle in human
evolution: how did our species transition from creatures interested in
little more than passing down their own genes to societies of
(generally) law-abiding (mostly) monogamists?

No one knows for sure when these changes happened, but climactic
swings that occurred between approximately 10,000 to 150,000 years ago
in the late Pleistocene period may have pushed once-isolated bands of
hunter-gatherers into more frequent contact with one another, says
Samuel Bowles, an evolutionary biologist at the Santa Fe Institute in
New Mexico and the University of Siena, Italy, who led the study. "I
think that's just a recipe for high-level conflict."

Tribes at war
By warfare, Bowles isn't talking about highly organised contests
between nation-states and their armies. Rather, this period of warfare
was probably characterised by ongoing skirmishes between neighbouring
populations.

"We're talking about groups of men who got out in twos or threes or
fives," he says. "They didn't have a chain of command and it's hard to
see how they could force people to fight."

For this reason, altruistic intent on the part of each warrior is key..
Each person would do better to stay home than to put their life on the
line for their neighbours – yet they still went out and risked their
lives, Bowles says.

To assess whether or not people with a random genetic predisposition
to altruism could flourish via armed conflicts, Bowles culled
archaeological and ethnographic data on the lethality of ancient
warfare and plugged them into an evolutionary model of population
change.

Cost of clashes
In ancient graves excavated previously, Bowles found that up to 46 per
cent of the skeletons from 15 different locations around the world
showed signs of a violent death. More recently, war inflicted 30 per
cent of deaths among the Ache, a hunter-gatherer population from
Eastern Paraguay, 17 per cent among the Hiwi, who live in Venezuela
and Colombia, while just 4 per cent among the Anbara in northern
Australia.

On average, warfare caused 14 per cent of the total deaths in ancient
and more recent hunter-gatherers populations.

The cost of losing an armed conflict as a group is high enough to
balance out the individual risks of warfare, especially if a
population is relatively inbred, Bowles' model concludes. Since
evolution acts on genes, it makes more sense to make more sacrifices
for a related neighbour than an unrelated one.

Since Bowles had no way of knowing how inbred Pleistocene populations
were, he compared contemporary hunter-gatherers such as African
pygmies and native Siberians. Individuals in these populations were
closely related enough to justify going to war, he found.

Inbreeding
"There's no doubt that his is a controversial view," says Ruth Mace,
an evolutionary anthropologist at University College London.
Inbreeding between the victors and any surviving losers would dilute,
not concentrate, altruistic genes, she says.

Bowles modelled this possibility in a previous paper and found that
even with a measure of inbreeding, altruists still win out. However,
he agrees that it would slow the evolution of altruism through
warfare. "A much better way to spread the genes is to kill everybody,"
he says.

Mark van Vugt, a psychologist at the University of Kent at Canterbury,
UK, notes that warriors could act in their own self-interest, not for
the good of the group.

"Studies on the Amazonian Ya̧nomamö people show that these warriors do
get a greater share of resources, they get more women, they sire more
offspring," he says. "How do you explain that there are individual
benefits for these warriors? There shouldn't be."

Still, van Vugt thinks Bowle's model is on the right track. Studies
show that people divided into arbitrarily chosen groups – say heads
and tails – behave altruistically to members of their group, but are
more hostile toward non-members.

"Together we provide different pieces of the puzzle. If they fit
together, they are starting to make sense," van Vugt says.

"Bowles modelled this possibility in a previous paper and found that
even with a measure of inbreeding, altruists still win out. However,
he agrees that it would slow the evolution of altruism through
warfare. "A much better way to spread the genes is to kill everybody,"
he says. "

The invading Xhosa and Zulu people killed as many San (Bushmen) males
as they could when they moved into Southern Africa but they included
the San women as wives/concubines (hence the presence of clicks in
these languages today). So this form of altruism may be relatively
specific to males.

Lance- Hide quoted text -

- Show quoted text -

I'm not sure what you mean by your last sentence.  Successful warriors
might receive sexual rewards from women in their own tribe and capture
some new wives for themselves.  So by fighting they might be lowering
their prospects of survival but increasing their prospects of
reproducing.  Does this count as biological altruism?  (Psychological
altruism is a rather different issue.)

Without reading the relevant  papers. books, research studies etc.,
it's difficult to know exactly how terms such as altruism are being
defined and understood, or what assumptions and simplifications are
being  incorporated in models.  Presumably there is a need to take
account of pre-disposing physiological factors such as hormones or
mirror neurones,  but also of many interactions between genetic,
environmental and cultural variables.  Fools rush in where angels fear
to tread.....

Dave Smith

I think the altruism referred to was the cooperation needed to wage
war, put oneself at risk for the group, etc.

Lance
.

Relevant Pages

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