[ExI] Predation and human evolution (long)

[lists1 at evil-genius.com]

Not sure why this didn't make it through last time...if it's being 
moderated, please let me know why.

On 9/27/10 11:46 AM, Keith Henson <hkeithhenson at gmail.com> wrote:
> Lions are a good example, they
> evolved the pride social organization as a response to lions killing
> lions.

This may not actually be true.  Lions may well have evolved their social
organization as a result of competition with large packs of spotted
hyenas, which (contrary to stereotypes) are accomplished predators that
kill most of their own prey (far more than lions, who steal much of
their food from hyenas), and who will absolutely dominate lions if they
have a numerical advantage.

In fact, it is thought that spotted hyenas are the reason male lions
exist: what is the evolutionary advantage to huge, hungry males that do
nothing but lie around, make the females hunt for them, and kill cubs
when they take over a pride?
(Warning: brutal reality.)
http://www.youtube.com/watch?v=xZRw0IYdf3g

Answer: because male lions (500# or more) can dominate almost any number
of spotted hyenas (100#-160#), whereas female lions (250#) will
absolutely be dominated if there are enough hyenas.  Here's what happens
when the males aren't around: the hyenas take everything.
(Nothing nasty in this one.)
http://www.youtube.com/watch?v=8zjPWpdyC74

Basically, male lions exist because of spotted hyenas.

> The line that led to humans escaped predation by the big cats a long
> time ago so there has been plenty of time for evolution to act.

Recent research suggest this is not at all the case.  We have spent much
of our history being predated by big cats...and most commonly, hyenas.
In fact, many sites that were previously interpreted as human-on-human
violence are, with new evidence, being shown as victims of predation.

Here's Homo Erectus being eaten regularly by "The Skull-Crushing Hyenas
of Dragon Bone Hill" (this is a great read, btw):
http://scienceblogs.com/laelaps/2009/06/the_skull-crushing_hyenas_of_d.php

 From the article: "It might be expected that such an ancient "crime
scene" would be rare, but new research has revealed that many important
hominin fossils bear tell-tale signs of predation. The group of
Australopithecus afarensis known as the "First Family", for instance,
may represent a massacre at the hands of carnivores, and the "Taung
Child" specimen of Australopithecus africanus was scored by the talons
of a large bird of prey. Even the fossils of the recently-described
early hominin Orrorin bear bite marks; the rest of the skeleton might
have proven elusive because a predator destroyed the rest."

This back-and-forth relationship continued well into the Late
Pleistocene, the time of Homo sapiens.

From: "Comparative ecology and taphonomy of spotted hyenas, humans, and
wolves in Pleistocene Italy"
http://www.u.arizona.edu/~mstiner/pdf/Stiner2004a.pdf

"The phenomenon of alternating shelter occupations by
humans and non-human predators began at least 200-
250 KYA in western Asia and Europe (e.g., BRUGAL
& JAUBERT, 1991 ; GAMBLE, 1986 ; STINER, 1991b,
1994 ; STRAUS, 1982), coinciding with greater cave
use by hominids overall. As noted by GAMBLE (1986),
alternating use of caves by hominids, spotted hyenas,
bears, and wolves was particularly common in the
Mediterranean Basin, with many examples from Italy
(e.g., BONFIGLIO et al., 2000, 2001 ; GIACOBINI, 1990-
91 ; PITTE & TOZZI, 1971 ; STINER, 1991b, 1994 ; WHITE
& TOTH, 1991), France (e.g., BRUGAL & JAUBERT, 1991 ;
VILLA & BARTRAM, 1996), Germany (e.g., GAMBLE,
1999), and western Asia (SPETH & TCHERNOV, 1998 ; and
on recent hyena dens, see HORWITZ, 1998 ; HORWITZ &
SMITH, 1988). In some cases, the spatial associations of
artifacts and carnivore-collected materials resulted from
the slope wash into natural traps (VILLA & SORESSI, 2000),
but other cases clearly resulted from primary disposal on-
site of materials by different predators at different times.
Where hominid components are thin and ephemeral,
carnivore components often are thick and easily
recognized, and vice versa."

Alternating cave use by humans and hyenas, wolves, and bears?  Why would 
humans give up a perfectly good cave unless they were under severe 
threat of predation?  Answer: they were indeed under severe threat.

Note that cave bears were present in Europe until perhaps 20,000 years
ago, and spotted hyenas did not disappear from Europe and Asia until
perhaps 11,000-14,000 years ago.

The argument that humans were historically more subject to predation
pressure than intraspecific competition is bolstered by the fact that
archaeological evidence of warfare is basically absent until the
evidence of agriculture is also apparent -- at which point it becomes
plentiful:

R. Brian Ferguson, "The Birth of War" (Natural History, July/August 2003)
http://andromeda.rutgers.edu/~socant/Birth%20of%20War.pdf

In conclusion: you may be correct about the role of religion in
intraspecific competition, but this role has only come about with the
advent of agriculture (which is only a few thousand years old for most
cultures), and would therefore appear to be more due to memetic
evolution within existing substrate than genetic evolutionary pressure.