Prehistoric conflict hastened human brain's capacity for collaboration, study says


Warfare not only hastened human technological progress and vast social and political changes, but may have greatly contributed to the evolutionary emergence of humans' high intelligence and ability to work together toward common goals, according to a new study from the National Institute for Mathematical and Biological Synthesis (NIMBioS).

How humans evolved high intelligence, required for complex collaborative activities, despite the various costs of having a big brain has long puzzled evolutionary biologists. While the human brain represents only about two percent of the body's weight, it uses about 20 percent of the energy consumed. Other costs of having a large brain include a need for extended parental care due to a long growth period, difficulties giving birth to larger-headed babies, and some mental illnesses associated with brain complexity. So how did the human brain evolve to become so large and complex?

Another long-running question is how did humans evolve strong innate preferences for cooperative behavior, as cooperative behavior is vulnerable to exploitation by cheaters and "free-riders." A free-rider doesn't contribute or cooperate and thereby undermines the effectiveness of the group's collaborative effort, something scientists call "the collective action problem." Thus, collaborative behavior is expected to be rare, and indeed, in animals it is typically limited to close relatives. Humans, however, are a unique species where collaboration is widespread and not limited to relatives.

In the new study published in the Journal of the Royal Society Interface, lead author Sergey Gavrilets, a professor of ecology and evolutionary biology and mathematics at the University of Tennessee, Knoxville, and NIMBioS associate director for scientific activities, developed a mathematical model that offers answers to both evolutionary puzzles.

The model shows that intelligence and can co-evolve to solve the problem of in groups and to overcome the costs of having a large brain.

The research points to the types of collective actions that are most effective at hastening collaboration. According to the model, collaborative ability evolves easiest if there is direct conflict or warfare between groups, what Gavrilets calls "us vs. them" activities. In contrast, collective activities, such as defending against predators or hunting for food, which Gavrilets calls "us vs. nature" activities, are much less likely to result in a significant increase in collaborative abilities.

The study also predicts that if high collaborative ability cannot evolve, perhaps for example because the costs of having a big brain are too high, the species will harbor a small proportion of individuals with a genetic predisposition to perform individually-costly but group-beneficial acts.

In addition, the model challenges influential theories on when large-game hunting and within-group coalitions first appeared in humans. Some scientists say that within-group coalitions and collaborative hunting came first and then subsequently created conditions for the evolution of collaboration in between-group conflicts. Yet, Gavrilets' model shows the opposite: that collaboration in between-group fighting preceded both within-group coalitions and collaborative hunting.

"Our ability to effectively collaborate with others is largely responsible for what our species came to be. The big question is how this ability first evolved when there are large metabolic and physiological costs related to size and when collaboration can be easily undermined by free riders. The model offers an answer which emphasizes the role of between-group conflicts in shaping unique human features," Gavrilets said.

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More information: Gavrilets S. 2014. Collective action and the collaborative brain. Journal of the Royal Society Interface. Published online 26 November 2014.
Citation: Prehistoric conflict hastened human brain's capacity for collaboration, study says (2014, November 26) retrieved 22 September 2019 from
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Nov 26, 2014
"Has long puzzled evolutionary biologists"

-But not all academics has it? This is the paper I have been posting here for years.

"There can be no doubt that a tribe including many members who, from possessing in a high degree the spirit of patriotism, fidelity, obedience, courage, and sympathy, were always ready to give aid to each other and to sacrifice themselves for the common good, would be victorious over most other tribes; and this would be natural selection" (Darwin, 1871)

-Darwin was aware of group selection, tribalism, and it's effect on human development. Trribalism is a very unpopular concept in the academic world because it indicates that many behaviors which are considered disruptive to modern society are in fact normal.

Normal does not mean acceptable. But it is easier to condition behavior by punishing people instead of educating them.

Nov 26, 2014
Humans developed a large brain because such a thing prevents the species from becoming overly-specific. Overspecialization promulgates extinction. The generality of the brain as a multiple purpose organ enabled adaptation to many varied ecological niches where humans could cling to existence even while their environment underwent radical and tumultuous ecological and climatic change

The computer is an artificial embodiment of the brain plasticity. It persists despite radical reengineering of it's hardware substrate and lack of a unique purpose. Indeed it's generality is the reason it does not disappear like the plastic record player or the wood-burning stove

Nov 26, 2014
as cooperative behavior is vulnerable to exploitation by cheaters and "free-riders."

In families, tribes, small towns, everyone knows who the cheaters are.
Under large, socialist/statist govts, cheaters can hide. Many among those in power.

Nov 26, 2014
as cooperative behavior is vulnerable to exploitation by cheaters and "free-riders."

In families, tribes, small towns, everyone knows who the cheaters are.
Under large, socialist/statist govts, cheaters can hide. Many among those in power.
The cheaters ryggy is referring to, perceive themselves to be members of other tribes. Cheating from their perspective is normal and natural. They reward this predatory behavior amongst themselves.

This behavior and attitude is identical to that of ryggys own tribe which will tend to prey on these 'cheaters', and will resent any restrictions on doing so on the grounds that it is not 'natural'.

Nov 26, 2014
No species can survive without some degree of collaboration. Collaboration is a theme of all living systems starting with bacteria. The trillions of cells in the human body function in altruistic collaboration to the point where they are prepared to die (apoptosis) as soon as their functional ability is compromised. Thus collaboration tends to evolve wherever it can. Even collaboration between species (symbiosis) is quite common and extends back as far as the first Eukaryotes (eg symbiogensis).

Each new level, scale or form of collaboration presents new challenges. It takes time for these to be overcome by natural and sexual selection alone, particularly when individualism is advantageous.

Nov 29, 2014
Chimp males (without very special or large brains) collaborate to attack & kill rival males. Termites & ants have tiny brains, but cooperate for fighting. More likely, human ancestors evolved larger brains when they had plenty access to brain-specific nutrients (e.g. DHA, iodine) when they dispersed intercontinentally along African & Eurasian coasts & rivers as far as Algeria (Aïn-Hanech), Java (Mojokerto), Georgia (Dmanisi) & the Rift (Turkana) 1.8 mill.yrs ago. Most waterside & (semi)aquatic mammals (otters, whales, seals, raccoons...) evolve larger brains than equally large relatives.
- S.Cunnane 2005. Survival of the fattest: the key to human brain evolution. World Scient.Publ.Comp.Singapore.
- S.Munro 2010. Molluscs as Ecological Indicators in Palaeoanthropological Contexts. PhD thesis Austr.Nat.Univ.Canberra.
- M.Verhaegen 2012. The aquatic ape evolves: common misconceptions and unproven assumptions about the so-called Aquatic Ape Hypothesis. Hum.Evol.28:237-266 .

Nov 30, 2014
Intelligence and brains are both genetically complex. That doesn't mean any one environmental factor (cooperation, nutrients) could not be responsible for an inflated trait in a species, but it implies such explanations are rare.

And , the balloney "aquatic ape" idea, which anthropologists have rejected? Oh well, another buffoon goes to my "ignore (from now on") list.

"Few paleoanthropologists have explicitly evaluated AAH in scientific journals, and those that have reviewed the idea have been critical. The AAH is one of many hypotheses attempting to explain human evolution through a single causal mechanism, but the evolutionary fossil record does not support any such proposal. The proposal itself has been criticized by experts as being internally inconsistent, having less explanatory power than its proponents claim, and suffering from the feature that alternative terrestrial hypotheses are much better supported.


Nov 30, 2014

The attractiveness of believing in simplistic single-cause explanations over the much more complex, but better-supported models with multiple causality has been cited as a primary reason for the popularity of the idea with non-experts.[3]"

[ http://en.wikiped...pothesis ]

Nov 30, 2014
@TGO: Darwin had no concept of genes, and didn't recognize that the selfish gene is the genetic vehicle that can be selected on.

Now Gavrilets, which has done interesting work elsewhere IIRC, modeled this as the never seen and non-mechanistic group selection. That can be remodeled as gene selection, or else shown to be non-existent in the cases I know of.

Mostly, I think his prediction is not well supported and have several better competitors.

Nov 30, 2014
@RKS: There are plenty of species that survive without collaboration. As a premier example, the bacteria (or was it an archeon?) that was found in deep South Africa mines inhabiting its own biosphere with no other species around.

Coevolution is compatible with genetics, and so is inclusive fitness and so kin selection even though it is by no means the norm. [ http://en.wikiped...election ]

Re mitochondria, the new phylogeny that derives the pre-mitochondria (while earlier works have been sloppy and looked at the proto- mitochondria, so weakened the outgroup resolution) show that it started out as a parasite like its kin such as Wolbachia. It stole ATP, not produced it - that out-transporter was grabbed by horisontal gene transfer, perhaps from some other infectious agent.

This is then a more likely outcome (and indeed in some cases Wolbachia is now a symbiont, if not yet endogenous), and has implications on the early co-evolution.

Nov 30, 2014
Bacteria are dependent on colonial behavior, are known to be able to sense the presence of others ('quorum sensing') and do not survive well if at all as individuals (depending on variety of bacteria).

Cooperation becomes more important, not less as species become more complex with sexually reproducing species being totally dependent on each other for the species survival.

Mammals are dependent on mothers for survival and do not develop such skills as language without exposure during maturation.

Considering the examples of cooperation contrasted with total independence it is clear that cooperation has been a constant theme of living organisms and is the one thing that clearly differentiates living from non-living chemical reactions over the shortest intervals (reproduction, self repair and sensing of the environment take time and are not continuous, homoeostasis is).

New biological innovations tend to be individualistic only initially but they soon spread and interweave.

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