|A street fight, via Wikipedia.|
Determining (3), of course, depends in part on the values we assign to (1) and (2). Being killed before reproduction obviously reduced fitness to zero, and being killed after reproduction eliminated all the kin altruism the individual would otherwise have engaged in. The impact on fitness of being injured depended on the severity of the injury, but it seems clear it would have been negative and serious. What we need to deduce the magnitude of (3) over human evolutionary history, then, is sound empirical estimates of (1) and (2). Unfortunately, however, these estimates are extremely difficult to make because the available evidence is sparse and often ambiguous. Broadly speaking, there are two lines of evidence available to us: studies of contemporary hunter-gatherers and the paleoanthropological and archeological record. There are several controversies around both lines of evidence, but for this post I'll focus on one type of evidence from the archeological record: depictions of violence in rock art.
A beautiful example of such a depiction is a San pictograph "Veg 'n Vlug" (Afrikaans: "Fight or Flight") that is near Clanwilliam in the Cederberg of South Africa. (Note: I've used the Auto-Level feature in Paint.NET to bring out some of the details):
John Parkington describes (large pdf; pp. 62 - 65) the scene thus:
The fight element is created by painting around a small recess in the rock surface to give the impression of a small cave from which a group of humans peer, one of them shooting arrows. A second group of humans, arranged as a procession and depicted apparently moving along a pair of red lines, face the cave occupants and also shoot arrows. From the ‘cave’ several people, most of them male, flee along more pairs of red parallel lines. One human figure, clearly lying prone is connected by these same lines to a strange seated figure holding the end of the lines, neither of them directly connected with the cave itself. From the neck of the strange seated figure a single red line leads to another small figure with upraised arms.Contrary to the hypothesis - favored by neo-Rousseauians like Brian Ferguson - that human evolutionary history was entirely (or largely) peaceful, then, we have at least an existence proof of such violence. Or do we? Ferguson has argued that pictographs seemingly depicting violence should not be interpreted literally, but rather metaphorically. In other words, "Veg 'n Vlug" doesn't depict an actual event, the artists meant something else entirely, or is perhaps an attempt at sympathetic magic. (To be clear, as far as I know Ferguson has never written about this specific pictograph. I'm illustrating the kind of argument he's made about other rock art depictions of violence). And there are certainly aspects of "Veg 'n Vlug" that isn't literal. Parkington continues from the above quotation:
This bald, but reasonably literal description gives no hint of the intriguing and enigmatic details that impart a deeper, but still obscure meaning to this apparently unified composition. Take the double red lines for example. They cannot, as might appear at first glance, be footprints or a path, because they connect the feet of those in the procession to the bow of one of the cave occupants and emerge from the bowstring to enter the mouth (or face) of the bow and arrow-wielding figure. The strange figure reeling in the lines from the feet of the prone, perhaps dead, figure cannot be manipulating footprints or a path in any literal way. It is likely that the double, parallel red lines are painted to illustrate some connectedness between people that is intangible but central to the meaning of the composition. The attachments to feet, hands, equipment and mouth probably indicate the nature of the connection but are not explicit enough to provide a definitive narrative.So what does this mean? Well, clearly, the pictograph cannot be strictly literal. Perhaps the artist(s) intended to convey some, now obscure, metaphorical meaning. Perhaps aspects of the drawing represent something abstract. Contra Ferguson et. al., though, I don't think it is reasonable to conclude that a metaphorical interpretation obviates a literal interpretation.
Take my avatar and favorite painting, A Philosopher Lecturing on the Orrery by Joseph Wright:
The painting has two, complementary, meanings. Whether Wright had in mind a specific instance of a scientist demonstrating an orrery (a clockwork-driven model of the universe), it's clearly the kind of thing that went on at the time. That is, there certainly were orreries, scientists, and scientists demonstrating orreries and the painting represents an instance of the latter. The painting conveys much more than just 'such-and-such' happened, though. Many metaphorical interpretations are possible, naturally, but Wright seems to have intended it as a celebration of science, of the Enlightenment. The point could be argued, but suppose we agree A Philosopher represents the Enlightenment. Does that mean we have to abandon a literal reading? Insist that the painting tells us nothing about orreries and scientists? Obviously not. Literal and metaphorical representations can, and often do, co-exist.
What this illustrates, I'm suggesting, is that however we interpret the non-literal aspects of "Veg 'n Vlug", we need not abandon a literal reading. In other words, even if there are abstract or metaphorical meanings we can assign to the pictograph, it still depicts two groups engaging in violence. It's necessary to go a step or two further, in fact. Not only can metaphorical and literal readings co-exist, we should apply Occam's Razor and favor a kind of interpretive parsimony: the simplest interpretation - the one that requires the fewest new assumptions - is likely the correct one. And in nearly all cases, the literal interpretation is the simplest.
Whatever metaphorical or abstract readings we assign to any pictograph do not necessarily obviate literal interpretations. And interpretive parsimony - favoring the simplest possible interpretation - cautions against metaphorical readings in the first place, and demands especially strong evidence before we elevate metaphor over straightforward representation. In short, unless we have strong reasons to think otherwise, pictographs like "Veg en Vlug" represent evidence of ancient violence.
 The word 'philosopher' at the time had multiple meanings, one of which was what we would now call a scientist.