Tolstoy, as promised...
Here's a great and relevant talk given by Steven Pinker at TED. It's well worth the 20 minutes to listen to:
http://www.ted.com/talks/lang/eng/steven_pinker_on_the_myth_of_violence.html
From a New Scientist article citing info from a paper who's full text is not available for free (I provide the link to the abstract anyway):
"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."
http://www.newscientist.com/article/dn17255-ancient-warfare-fighting-for-the-greater-good.html
http://www.sciencemag.org/cgi/content/abstract/324/5932/1293
Regarding modern day hunter gatherer mortality, I've got this blog quoting an article which also unfortunately does not make its full text available for free. Again, the abstract is also provided.
"Violence is the major cause of death among the precontact Ache (55% of all deaths) and very important among the Hiwi (30% of all deaths), but notably less important in the two African societies and the Agta (3–7% of all deaths). Indeed, the crude homicide/warfare death rates per year lived are more than ten times higher among the Hiwi and Ache than among the Hadza or !Kung (1/100 and 1/200 per year for precontact Hiwi and Ache, respectively, vs. 1/2500 and 1/3000 for the Hadza and !Kung, respectively). Blurton Jones et al. (2002) suggested that this may be due to the more pervasive effects of colonial governments in Africa and the reduction of intertribal warfare."
"If high mortality, warfare, homicide, and accidental trauma are typical of our Paleolithic ancestors, the Hiwi mortality patterns may be more representative of the past than those derived from other modern hunter-gatherers. If so, several observations about the Hiwi are important. First, conspecific violence was a prominent part of the demographic profile, accounting for many deaths in all age and sex categories. Most of the adult killings were due to either competition over women, reprisals by jealous husbands (on both their wives and their wives' lovers), or reprisals for past killings. The criollo-caused killings were motivated by territorial conquest. Moreover, infanticide (especially on females) constituted the highest mortality rate component of all Hiwi conspecific violence. Second, no predation deaths were reported despite attacks by anacondas, Orinoco caimans, and piranhas, and the presence of jaguars in the area. Accidents associated with the active-forager lifestyle were common, but disease was a more important killer, accounting for nearly half of all deaths. This suggests an adaptive landscape in which success in social relations, competitive violence, and disease resistance are paramount. This may partially explain why many of the genes that appear to have been under strong selection in the past 50,000 years affect either disease resistance or cognitive function (Wang et al., 2006), presumably related to success in an atmosphere of frequent violent social competition (Hill et al. 2007:451)."
http://johnhawks.net/weblog/reviews/life_history/aging_evolution/hill_2007_hiwi_mortality.html
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJS-4MHNRJ5-2&_user=10&_coverDate=04%2F30%2F2007&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1289621447&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_
userID=10&md5=1a945d3884b45be8625c7830004a7113