You wouldn’t know it by current world events, but humans actually evolved to be peaceful, cooperative and social animals.
‘Man the Hunter’ theory is debunked in new book, February 18, 2006, By Neil Schoenherr
So begins a discussion regarding humans as a prey species rather than predators.  It isn't true, and it doesn't even make any sense.  After all, what do any of those traits have to do with being a predator or prey?

Does anyone believe that wolves or lions aren't social?  or cooperative?  or peaceful amongst themselves?

More importantly to use the term "evolved" is an extreme abuse of the biological concept of evolution since clearly humans have "evolved" to be just as they are.  No more, no less.  This statement suggests a direction to evolution, as if somehow there was an "intent" that had been circumvented.  In short, it is simply wrong.
The idea of “Man the Hunter” is the generally accepted paradigm of human evolution, says Sussman, who recently served as editor of American Anthropologist. “It developed from a basic Judeo-Christian ideology of man being inherently evil, aggressive and a natural killer. In fact, when you really examine the fossil and living non-human primate evidence, that is just not the case.”
I'm not even sure what to make of this statement, except that it is decidedly not scientific.

Inherently evil?  Really?  What does "natural killer" even mean?

The fact of the matter is that predation is not so simply characterized as a separate issue from being prey.  All predators are also prey, whether it be from scavengers, or from the overt killing, especially of the young.  Wolves are subject to predation by bears.  Lions are subject to predation by hyenas and vice versa.  Cheetahs are preyed upon by lions, and so on (1).

Yet, in no instance would anyone suggest that these creatures are not also predators.

The simple dynamics of life indicate that the easiest, least risky method of obtaining food is the one that will likely be pursued.  As a result, we can comfortably predict that the sick and weak will be primary candidates of predation [regardless of the species].  Similarly, we can be quite confident that almost any creature's young will be a candidate if it is not adequately protected.

One problem occurs in the arbitrary designation of predator and prey animals.  This isn't particularly helpful, but instead we need to consider whether animals are capable of killing/eating other animals or not.  If they are not, then there is nothing further to consider.  If an animal is capable of killing or scavenging another animal, then the choice of food is going to be determined by availability and risk.

Because of the energy [calories] and competitiveness of predation, there are far fewer predators in any given territory.  Therefore, it follows that the most common prey will be those animals that dominate a particular territory and this will likely be a herbivore or fructivore.  However, the connotation of prey is often used to imply weakness despite the fact that most such adults represent a serious risk of injury and even death to predators.  Despite appearances, a giraffe can decapitate a lion with a kick.

Since most herbivores and fructivores lack the type of adaptations necessary for extensive fighting with predators, their survival strategy is typically to run rather than confront (2).  Most predators cannot sustain the energy required for extended chases, so this is a viable strategy to avoid predation.

On the other hand, cooperation and social organization is often a necessary trait for predators, and may exist in a variety of creatures (3).  Again, we find that if there is an energy benefit that can be derived by cooperation, then we will tend to see that manifest in a group.  For predators, if there is no benefit, then we would expect to not see social groups and cooperative behaviors.  For example, wolves benefit from being social because they can collectively take down larger prey, so the energy investment in a hunt produces sufficient food for the group and distributes the risk.  In large predators like Grizzly bears or tigers, there is little benefit in cooperation, since a single kill wouldn't be sufficient for a larger group.  As a result, there is no advantage in cooperative hunts.  However, one can also see that when food is plentiful, then even solitary predators [like grizzly bears] do not engage in confrontation but can be sufficiently social around a large food supply [i.e. salmon stream]. 

In short, the simplistic notions of aggressiveness are simply anthropomorphism.  An angry water buffalo is no different than an angry grizzly bear when it comes to confrontations.  A hippopotamus is no push-over when it comes to aggression, and neither are elephants.

The point is that all creatures have adapted to acquire their energy requirements in various ways, while simultaneously having to be responsive to situations of where they may be subject to predation or injury.

To suggest that humans are somehow different is preposterous on the face of it.  When comparing primates, one could hardly assess them as being non-violent, peaceful and lacking in aggression.  

So, were humans hunted?  Unlikely, although they were undoubtedly preyed upon when opportunities presented themselves.  In turn, humans were also likely hunters.  Initially it may have been smaller prey or scavenging, but with tool-making, their cooperative, social structures provided a means to take down much larger prey.

The problem with arguing that humans were initially a prey species is that it requires a transition [to predation] that makes no biological sense.  The whole concept of evolution is that specific traits and skills are refined over time so that those best suited tend to experience an increase in fitness.  By what scenario can anyone suggest that a prey species "evolves" to specialize in its niche, only to make the transition to a completely different niche for which it possesses no traits?

Certainly one can examine any predator's ancestry and eventually arrive at some species that may have been regularly preyed on.  However, there is also little doubt that it would be regarded as a completely separate species, possessing none of the traits that the current predatory creature has.
Australopithecus afarensis didn’t have tools, didn’t have big teeth and was three feet tall. He was using his brain, his agility and his social skills to get away from these predators. “He wasn’t hunting them,” says Sussman. “He was avoiding them at all costs.”
So, why is this even relevant since the comparison is even being made with a species that belongs to a different genus as humans.  There is little doubt that if one goes back far enough we would find a rodent-like ancestor and an egg-laying ancestor, etc. (4) However, we generally wouldn't expect to see headlines claiming that "Humans lay eggs".

Just looking at the Maasai tribesmen engaged in a lion hunt to demonstrate that humans [even individually] are quite adept at confronting large predators, regardless of the dangers involved.  To suggest otherwise is to propose a theory that suggests that one day we may truly run into "killer bunnies".

The simple truth is that humans became better predators because they were predators to begin with.  The fact that there were larger predators doesn't change that.  The fact that humans could also serve as prey doesn't change that.

As mentioned earlier being a predator does not render one exempt from predation. However a more serious problem occurs when one extrapolates interpretations from the bones of ancestors.  There is simply no way to establish the manner of death, so a child or adult that had starved, or was fatally injured, or died of thirst, could well have been scavenged by other predators, as well as birds and now be considered as "evidence" regarding the prevalence of such encounters.

In short, such descriptions are guilty of assigning a directionality to evolution such that prey animals eventually become predators, which is little more than many of our "feel-good" philosophies about not being a victim.  

In fact humans have long held the capacity to kill, just as most primates have and that they were not the peaceful, passive creatures that Sussman would have you believe.  In fact, what should come as no surprise, is that they were and continue to be just like every creature that has ever lived, being both predator or prey depending on the circumstances.

Unfortunately, we can never be absolutely sure how our ancestors lived nor all the conditions that they may have been exposed to.  Certainly considering modern primates may offer some clues, but they are not definitive, since it is clear that modern primates did not experience the same evolutionary trajectory that humans did.  One other thing is certain.  If we are making a claim regarding human behavior, then it can't be radically different than anything ever observed in other animals.
Sussman and Hart provide evidence that many of our modern human traits, including those of cooperation and socialization, developed as a result of being a prey species and the early human’s ability to out-smart the predators. These traits did not result from trying to hunt for prey or kill our competitors, says Sussman.
The problem with this assessment is that we never learned to out-smart the predators.  When opportunity presents we still fall victim just as readily as ever (5).  So, even though we see a tremendous increase in our ability to hunt, track, and plan, we have learned virtually nothing about predator avoidance.  

In fact, I would argue that our brain and the development of language evolved precisely because we were hunters.  Our ability to make tools, abstract scenarios, plan future events, and interpret data from the environment would have been instrumental in our ability to hunt large prey.
The study offers evidence that these primates evolved to be good fathers, an important attribute for protecting young from predators.

It's possible a similar system of mate fidelity aided the group cohesion needed to minimize predation in early humans, he said.
This is simply wrong, since all social predators have similar traits, as witnessed by observing a wolf pack, for example.  From here we now descend into the evolutionary psychology descriptions that plague all such studies.
Then why do we walk around so anxious, so full of fear? ... The answer is our legacy of ancient fears, the result of having spent millions of years running from predators. Our fear response is more influenced by the ancient species we struggled to escape than any modern challenges.
So, now we know how the leopard got its spots, oh, sorry I mean how humans acquired anxiety.  Yet, this is merely a fanciful tale.  It is quite revealing to assess the anxiety level of these animals in the linked video.

Unfortunately, the average predator's offspring has a 50% change of dying due to starvation, and every hunt risks injury if not death.  The ability to track and locate appropriate game also clearly requires some effort, and given the possibility of also being preyed upon, one can't suggest that humans are unique in experiencing fear or anxiety (6).

In conclusion, we can surmise that humans [genus Homo] were predators or scanvengers, that were also likely prey of opportunity.  Using this relationship as an explanation of human social behavior, language, and brain size is quite a stretch.  Since predator/prey relationships have existed as long as there has been life on this planet and there are no other creatures that exhibit such human traits, then whatever the impetus was for us acquiring these abilities, it extended beyond a simplistic predator/prey explanation.

(1) ------------------------
A great horned owl had killed the hare, but predator became prey as a lynx killed the owl and pirated the hare for itself.
(2)  This particular video link demonstrates the risks predators must take, and shows how even a gazelle can gain the upper hand on a cheetah.

(3) While cooperation occurs in "prey animals" it is often less well defined, primarily because there's not much to cooperate about.  In general, most such cooperative behavior would be defensive [i.e. such as mobbing], whereas with predators there is generally a higher degree of social organization that involves hunting, defense, and sharing of resources. Of course, there is no general criteria that can be applied to all species.

(4) --------------------------
At least one of the devoured primates, an early ape called Proconsul, is thought to have been an ancestor to both modern humans and chimpanzees.
Proconsul is an extinct genus of primates from 23-25 million years ago.  So how far back do we want to go to consider irrelevant traits [which we don't know anyway]?  What is relevant is that we don't actually know the direct ancestor of the genus Homo, so all such considerations are purely speculative.  In other words, there is a million year gap between Australopithecus afarensis and Homo habilis.

(5) Most indications are that humans are not prey of choice, but rather prey of opportunity.
Attacks have increased dramatically during this time: they peak at harvest time each year and are most frequent in areas with few prey apart from bush pigs (Potamochoerus larvatus), the most common nocturnal crop pest.
(6) When the subject of animal consciousness, or emotions comes up, invariably one gets the traditional lecture about anthropomorphism, despite overwhelming evidence that animals experience many of the same mental states that we do.  When an animal possesses ears, we don't question whether they can hear.  When we see an animal's nose or eyes, we don't question whether they can smell or see.  Yet, somehow when we determine that the amgydala is the source of many of our emotional states, we question whether the amygdala in an animal's brain can fulfill a similar function.

This is reverse anthropomorphism, where one can postulate that the same identical structures somehow don't work or produce different results from what all the evidence indicates.

The only difference between humans and animals in this regard is that we  have the ability to vocalize our feelings, and to engage in emotions based on events that don't exist anywhere except in our brain.  We can be frightened of things that don't exist.  We can imagine fearful situations that have no basis in fact.  In short, we can victimize ourselves by complete fantasies.

In that respect, I would concur that animals lack such an ability.  Whether it be due to experience or anticipation of the future, animals can certainly utilize their memory and extrapolate that information into the future as experience.  However, there is nothing that indicates that animals can simply fantasize.

Interesting primate behavior:

Interesting predator/prey behavior:

Additional reading: