“The consensus is much as Wood concluded, ‘it is at present unclear with which of the two extant species of Pan the modern H. sapiens should be compared.’” Wrangham, R. & Pilbeam, D (35)

A number of people have argued that the bonobo is better suited for designation as the early human prototype. If that is the case, why is it that chimpanzees are documented tool-users, but not bonobos? That alone nearly bumps the bonobo from contention. Of course, the either/or reasoning is mistaken. Either the chimpanzee is our behavioral precursor, or the bonobo.

Frans de Waal writes,

“We have the fortune of having not one but two inner apes, which together allow us to construct an image of ourselves that is considerably more complex than what we have heard coming out of biology for the past twenty-five years.”(36)

In the least, the early ancestry of our kind is still in unclear. Will Ardi (Ardipithecus ramidus) and other yet uncovered ancient primate remains come to our rescue? For now, the issue remains a puzzle with few pieces from which to construct a bigger picture. As this passage from essay “African Apes As Time Machines” illustrated:

“‘About 5 million years ago forest-ranging, knuckle-walking apes–much like the living chimpanzees–evolved…into the earliest humans…(A. L. Zihlman, 1978)’. This view has successfully challenged alternatives such as the prebrachiatrionist model (descent from a generalized terrestrial quadrupedal ape), the gibbon model (descent from a terrestrial gibbon), and the Miocene fossil model (descent from a thick-enameled magadont). Increasingly strong support has come from our growing confidence in the molecular evidence that human and chimpanzee lineages diverged after the split with gorillas; the recognition that Pan is little changed phenotypically from the African ape ancestor; and the discovery that the earliest known australopithecine fossils (probably within 1-2 million years of their likely split from the chimpanzee lineage) have more chimpanzee-like features than do later species. For such reasons, “the common ancestor of humans and chimpanzees was probably chimpanzee-like, a knuckle-walker with small thin-enameled cheek teeth.” (37)

Again, Frans de Waal approaches the question of the human ancestral prototype, as seen through current cousin species, with an informed reasonableness -

“Instead of inquiring which species, the bonobo or the chimpanzee, most resembles us humans, we can more fruitfully ask which elements of our social life are shared with one or the other and which elements are uniquely ours.”
(38)

From within that quote we can extract this essential point: we are bags of genes (so to speak). We have inherited not one monolithic genetic package from the past, but individual genes and gene-strings, no doubt. From many diverse sources. We are not the fruit of a single tree of life, but of a bush. Sure, our lineage can seem neat and clean when we follow a line of paternity (usually) backwards. But really. Each of us has two parents, four grandparents, 16 great-grandparents, etc. A clean line of descent is surely a handy illusion.

We share genes with many cousin species. In the end, a piecemeal approach to speculations of the origin of human nature might be wiser. Thanks to the cut and splice nature of chromosomal reproduction, we arrive at this insight: Each individual, each species, that ever lifted itself off the table of creation could be named “Frankenstein.”

—–

(35) Wrangham, R. & Pilbeam, D., “African Apes As Time Machines,” in Galdikas, B. M. F., Briggs, N. E., Sheeran, L.K., Shapiro, G. L. & Goodall, J. (Eds.), All Apes Great and Small, Volume I: African Apes, Kluwer Academic / Plenum, New York, 2001, p. 6
(36) de Waal, F. Our Inner Ape: A Leading Primatologist Explains Why We Are Who We Are, New York, Riverhead Books, 2005, p. 237
(37) Wrangham, R. & Pilbeam, D., 2001, p. 5
(38) de Waal, F. Peacemaking Among Primates, Harvard University Press, Cambridge, MA, 1989
p.227

Technorati Links: evolution, psychology

Culture is so deeply ingrained in us it feels natural. Call it second nature.

What is culture? Here’s one way of looking at it:

“Culture” in this sense refers to a population-specific set of behaviors acquired through social learning, such as imitation.

That from the ScienceDaily post, New Evidence Of Culture In Wild Chimpanzees.

Yes, chimpanzee populations have their own, distinct cultures. Okay, maybe those cultures a very rudimentary — relative to ours — and they lack the startling array of accoutrements and fashion accessories our own culture colors and clutters our lives with.

While chimpanzees use neither a fork nor a set of chopsticks to eat, there are differences in what individual chimps from different populations will do when honey is on the menu.

Kibale Forest chimpanzees use sticks to get at the honey, whereas Budongo Forest chimpanzees rely on leaf sponges — absorbent wedges that they make out of chewed leaves.

That’s culture all right. I imagine that were you to take a honey-eating chimpanzee’s stick away and place a leaf sponge in its hand instead, the chimp would respond, “Huh?” Just as I image that were you to visit a very foreign culture and attend a ritual of some sort and, at the door, discover that “oh no, we don’t wear clothes during the ceremony — you’ll have to take yours off,” your response would likewise be “Huh?” What, no clothes in public? Why that’s not . . . natural?

Technorati Links: anthropology, chimpanzee, culture

The title: Wild Chimps Have Near Human Understanding of Fire

You may wonder how it was determined that wild chimpanzees have near human understanding of fire. Were the chimps given #2 pencils and a fire fighter proficiency test? Joking aside, here is how chimpanzee understanding was gauged:

Data on the chimps’ behavior with seasonal fires was collected by Pruetz during two specific encounters in March and April 2006.

Field observations on two occasions? Poor quality and quantity of data, I’m afraid. From that information we get the claim, as a subtitle reiterates it –

Chimps have calm understanding of wildfires

A report of the events includes this:

The researchers interpret the chimpanzees’ behavior to the wildfires as being predictive, rather than responsive, in that they showed no signals of stress or fear — other than avoiding the fire as it approached them.[bold added]

That one bold word says a lot. It also highlights why a finding/claim such as above should be met with a healthy dose of skepticism.

While the interpretation of field observations reported in this piece might be spot-on, it might also be significantly off-the-mark. For the interpretation of observed behavior can be something like the interpretation of inkblots and other fully or relatively vague stimuli/events.

Technorati Links: chimpanzee, primatology, skepticism

By definition human beings are the most civilized species. The online dictionary, thefreedictionary.com, provides this on civilized:

Having a highly developed society and culture.

“Highly” is certainly the operative word here. Chimps do live in implicitly organized, social groups that pass on behavioral habits (customs) to their offspring. So the difference is one of degree. At least beyond the gadgets, goods and tools provided by high technology that the vast majority of us own and use but in no way deserve credit for developing.

Still, chimps can be quite brutish, indeed. Is the bonobo a “more civilized” cousin better suited to be first-in-line for comparison to our kind? Consider sexual behavior. (Sexual behavior and civility? Yes. Hang with me.) Female bonobos are in a sexual attractive state for 3/4 of their cycle (chimps – 1/2); they have more forward-facing openings to their vagina and, not surprisingly, engage in frequent face-to-face sexual intercourse. (11)

How does this pertain to being more civil, more community-friendly? It is believed that frequent, face-to-face sexual activity can help establish and maintain a pair bond. And pair bonds (monogamous behavior) leads to family-friendly, less strife-filled communities.

In a sense, political conservatives have it right. Strong pair bonds can play a role in a more tranquil society. Of course, their insistence on procreation-only sex is ludicrous. In humans and in bonobos, they idea is frequent sex for the sake of social relations.

But here’s the thing. Bonobos don’t form long-lasting male-female pair bonds. In a sense, they extend their sexuality further into their social group. At times they seem to use it as the equivalent of the human handshake. And, brace yourself, female-to-female clitoral rubbing is fairly common.

So while both the bonobo and human appear to use sexuality as a sort of social glue (lubricant?), with humans the sphere of seeming recreational sexual activity is at least overtly constrained to the pair bond (or pre-pair bond).

Relevantly, primatologist Frans de Waal includes discussion of bonobo sexuality in his book, Peacemaking Among Primates. If humans engage in “make-up” sex, bonobos are masters at it.

The “free love” aspect of bonobo behavior does have this additional consequence (and a very socially significant consequence it is): when females are freely polyamorous, it removes male sexual possessiveness from dominance disputes.(12) And, judging by bonobo male behavior, subtracting the resource of wombs (as the only way to bring progeny to fruition) from the equation of hierarchical motivations substantial deflates its importance. Without sex as a motive for males to squabble about, battle, posture, etc., what other reasons are there? Food maybe, better nesting sites, I guess. It seems that males just don’t get all that riled up about climbing a ladder of dominance if all it leads to is a better night’s rest.

As a direct result of sexual access to females being largely removed from group dynamics, the bonobo has been called the “egalitarian ape.” Funny, subtract sexual possessiveness and jealousy, etc., from a social group and it’s amazing how well everyone can get along. Of course, easier said than done, especially for some species more than others.

Female human beings, of course, do not display the same degree of polyamorous behavior. Does their potential merely lie latent? What about human males — are they sexually possessive? The answer to this question will help us determine whether or not the bonobo is a closer behavioral cousin to our kind than the chimpanzee.

Beyond the male bonobo being individually less despotic in behavior — attempting to rule by brute force — than the male chimp, “adult male-male bonds are not as pronounced in any known bonobo population as they are among chimpanzees.” (13)

As a number primatologists have hinted, the subtraction of male sexual possessiveness (of female wombs as a resource that can be successfully hoarded and guarded) can explain a lot of the bonobo’s apparent pacifism. Other resources instead become the focus of bonobo political behavior (the investment-in and protection-of social relations for ultimately pragmatic reasons).

A number of writers have pointed to the bonobo as a more “feminist” primate. And, indeed,

“As a result of such maternal interventions, the highest-ranking males in a bonobo community tend to be the sons of the highest-ranking females. Male alliances are little developed, which allows females to exert considerable influence.” (14)

But this has nothing to do with any inherent value or worth of females, or males for that matter. Ultimate male/female status or worth is a narrow-minded human concern. Are males better? Better for what? Are females better? Better for what?

As for a maternalistic social organization (hierarchy), while this is a fascinating difference from what you find in chimpanzee social groups, the structure nonetheless serves a purpose. The important question is: what purpose is that? Behind supposedly more or less virtuous behavior and social relations we will find important, pragmatic consequences. At least historically so.

Consider this test case: bonobos seem to have more “relaxed” inter-group interactions.(15) Is this because the bonobos are a more highly evolved creature? What’s the advantage, in terms of natural selection, for that? Is it possible that the more placid inter-group interactions are primarily the result of such things as less sexual conflict between groups and other things, such as abundance of food, hence a reduced incentive to view others as a threat to valued resources?

So sure, there is a notable “lack of male-female aggression and inter-community violence” in bonobos, relative to chimps. (16) Still, as Christopher Boehm, author of Hierarchy in the Forest: The Evolution of Egalitarian Behavior, has argued, it is possible that the Swiss-Army blade of potential bonobo male hierarchical strivings is not wholly absent, but successfully “counterbalanced by coalitions of females.” (17)

Once again, we should wonder what political purpose these female coalitions serve. For evolution cares not a whit about virtue in a vacuum.

As it turns out, bonobos may not be so fully peace-love-and-equality primates after all. In his book on human evolution, Tree of Origin: What Primate Behavior Can Tell Us About Human Social Evolution, Frans de Wall makes these somewhat contrarian points about the bonobo:

1. Female bonobos do seem to establish hierarchies, though these are more loosely guarded and appear to be based on age and residency.

2. Males do compete for rank, sometimes fiercely at times. Their overall status, however, seems strongly influenced by the status of the individual’s mother.

3. In a turn of the tables, females will hoard and guard prized foods — a valued resource. They will freely fend off males and thus “dominate” them. (18)

My guess is that if you were to place chimpanzees in physical and social environments similar to the bonobo . . . they would become more bonobo-like in behavior. Over time.

What is the nature of human beings in our own time? Good question.

These words of another blues song just caught my attention: “I’m going to kill my old lady, I caught her messing with another man.”

Sexual possessiveness anyone?

Chimpanzee, bonobo: does one primate represent the worst of human behavior, the other the better? Maybe. At least at first glance. We’ll be taking a second glance at the bonobo next.

—

(11) de Waal, F. Peacemaking Among Primates, Harvard University Press, Cambridge, MA, 1989
(12) Boehm, C., Hierarchy in the Forest: The Evolution of Egalitarian Behavior, Harvard University
Press, Cambridge, MA, 1999.
(13) King, B., The Dynamic Dance: Nonvocal Communication in African Great Apes, Harvard University Press, Cambridge, MA, 2004, p. 33
(14) de Waal, F. B. M., (ed.), Tree of Origin: What Primate Behavior Can Tell Us About Human Social Evolution, Harvard University Press, Cambridge, MA, 2001, p. 58
(15) Wrangham, R. & Pilbeam, D., “African Apes As Time Machines,” in Galdikas, B. M. F., Briggs, N. E., Sheeran, L.K., Shapiro, G. L. & Goodall, J. (Eds.), All Apes Great and Small, Volume I: African Apes, Kluwer Academic / Plenum, New York, 2001, p.13
(16) King, B., 2004, p. 31
(17) Boehm, C., 1999, p. 30
(18) de Waal, F. B. M., 2001, “Apes from Venus: Bonobos and Human Social Evolution,” page 56.

Technorati Links: evolutionary psychology, primates

I will develop and discuss this aspect of chimpanzee psychology — and possibly our evolutionary heritage as it pertains to superstitious and religious behavior — in a future series of posts in my Almighty Alpha project. The title to that series: “The Buds of Religious Behavior.”

In the near term, we will continue our examination of whether or not the chimpanzee deserves identification as the truest proto-human and thus legitimate focus of evolutionary psychology. The following three bits of information illustrate why I believe Pan troglodytes is the best candidate for providing clues to the evolution of human behavior, including religious stories and rituals.

1. “Unlike monkeys, who in most cases have a rigid social structure, chimpanzees have a very loose social structure.” (4)

Groups and leaders seem to be temporary. Both chimp and human. Can a I get an “amen” from the congregation? Or will there be an attempted coup instead? But wait! I’m just speaking for the Big Guy.

2. Not only is “Chimpanzee social behavior…the most plastic and human like among that of existing nonhuman primates,” but chimpanzees share the what seems to be the bulk of social emotions that humans display. (5)

Case in point: chimpanzee mothers who experience a death of their infant frequently drag around the lifeless body for days on end. While no human mother does this literally, the figurative equivalent can occur for months and even years on end.

3. “Mutual grooming is interdependent. Moreover, unlike other primates, chimpanzees engage in social grooming cliques and clusters, which is far more complex than the usual grooming dyad [of other primates] (Nakamura, 2003).” (6)

This is noteworthy because simple, uni-directional grooming establishes a relatively straightforward relationship of greater and lesser. But mutual and social grooming? This class of behavior seems to be a blunt instrument next the precise meaning of dominance relations. Okay, you value our relationships, and we are “in this together.” But what do we expect from one another and in what circumstances. How is this an advance? The instrument becomes many-purposed. But this necessitates an intelligence and capacity for learning the appropriate ways to use it.

The incredible brain growth and intelligence in human evolution was first attributed to advanced tool use. Seeing that hominid tool kits, and, presumably, tool use, varied little over hundreds of thousands of years, that idea has pretty much been discredited. Lately the reasoning for human brain growth has focused on social intelligence. Homo sapiens tend to live in not only larger social groups than other primates, but in groups with vastly more complicated relationships. Like chimpanzees, but more so.

Still, we have yet to take a good look at another very close primate relative: the bonobo, or “pygmy chimpanzee.” That’s where we next turn.

—

(4) Bourne, H., The Ape People, Putnam, New York, 1971.
(5) Power, M. The Egalitarians: Human and Chimpanzee, Cambridge University Press, Cambridge, 1991, p. 7
(6) McCrew, W. C., The Cultured Chimpanzee: Reflections on Cultural Primatology, Cambridge, Cambridge University Press, 2004, p. 135

Technorati Links: evolutionary psychology, religion

In future posts I will address questions about just how scientific evolutionary psychology is and can be (section titles: “Science and the Educated Guess,” and “Indirect Evidence and Possible Tests”). But putting that very-important issue aside right now, there is an essential question begging to be asked: Why the heavy focus on chimpanzee behavior?

There are a couple reasons for this.

First, chimpanzees are the most and best studied of the non-human primates. Second, DNA analysis has found that of any species, Pan troglodytes is most genetically similar to Homo sapiens.

But wait. The bonobo, or Pan paniscus, is as closely related to us as are chimps. It seems. While chimps and humans have a between 1 and 2% dissimilar genetic material, chimps and bonobos — a cousin species of the chimp, previously called the “pygmy chimp” — have approximately .3% non-shared genes. Because bonobos are usually lumped in with chimps, it is difficult to determine whether one or the other is a closer genetic kin to us. At least one biologist, Alison Jolly of the University of Sussex, has concluded that the bonobo is “no closer” to the human than is the chimpanzee.(1) Triglodyte or paniscus: Will the truer proto-human please stand up?

It is my present belief that chimpanzee behavior provides greater insight into human behavior. The late Roger Gould saw it this way, too:

“Inasmuch as morphologies can be interpreted correctly as reflections of behavior, therefore this suggests that the common ancestor was likely to have been more chimpanzee-like than bonobo-like in aspects of its behavior that were correlated with cranial development.” (2)

Of course, human beings are ultra-adaptive, if ultra-anything. I have previously argued that human nature could be compared to a Swiss Army knife. What is our true nature? Well, it depends upon the task at hand. Under some conditions we may be more triglodyte-like, in others, paniscus-like.

But wait. Recent research has suggested that the better primate to use as a guide to human nature is . . . the orangutan.

Rather than relying on genetic analysis, researchers John Grehen and Jeffrey Schwartz looked at physical characteristics of primates to draw conclusions about our family tree and the nearness of the branches of other species.

Schwartz and Grehan scrutinized the hundreds of physical characteristics often cited as evidence of evolutionary relationships among humans and other great apes-chimps, gorillas, and orangutans-and selected 63 that could be verified as unique within this group (i.e., they do not appear in other primates). Of these features, the analysis found that humans shared 28 unique physical characteristics with orangutans, compared to only two features with chimpanzees, seven with gorillas, and seven with all three apes (chimpanzees, gorillas, and orangutans). Gorillas and chimpanzees shared 11 unique characteristics. (3)

Physical characters that our kind more closely share with orangutans include thickly enameled teeth.

Should the orangutan now stand out as the go-to species for evolutionary psychologists? Probably not. More research is needed. But the orangutan-hypothesis clearly exposes the sketchy state of our current knowledge.

Back to the chimp-bonobo face-off. The greatest challenge to using chimp behavior as the best source of clues to human primate evolution comes from the bonobo. A number of experts have been arguing for some time that the relatively pacifist, “make love not war,” seemingly egalitarian bonobo is a better psychological match to our kind.

By focusing on the chimp am I thus painting an inaccurate picture? Maybe so, even with the proviso provided by my Swiss Army knife analogy. But maybe not. One thing is for sure: the bonobo question is important enough to further explore.

—

(1) Jolly, A. Lucy’s Legacy, Harvard University Press, Cambridge, MA, 1999.
(2) Gould, R. V. Collision of Wills: How Ambiguity About Social Rank Breeds Conflict, University
of Chicago, Chicago, 2003, p.6
(3) John R. Grehan and Jeffrey H. Schwartz, “Evolution of the second orangutan: phylogeny and biogeography of hominid origins,” Journal of Biogeography, 2009

Technorati Links: evolutionary psychology, primatology

A large majority of the chimpanzees in the study showed a significant bias towards right-handed gestures when communicating, which may reflect a similar dominance of the left hemisphere for communication in chimpanzees as that seen for language functions in humans. [source]

The news was not a surprise to me, for a few years ago I had attended a lecture on the handedness of chimps. The focus of that research, however, was slightly different. It tested hand preference during object manipulation and tool use. One interesting tidbit I learned was that when chimps throw stones (whether fastball or change-up), they tend to hurl them righty.

That research was conducted by American researchers in Georgia. This newer research had a different set of investigators, lending greater credence to it.

The French co-authors, Dr. Adrien Meguerditchian and Prof. Jacques Vauclair, from the Aix-Marseille University (Aix-en-Provence, France), also point out that “this finding provides additional support to the idea that speech evolved initially from a gestural communicative system in our ancestors. Moreover, gestural communication in apes shares some key features with human language, such as intentionality, referential properties and flexibility of learning and use”.

Very interesting.

Last year I ended my post with words equally valid today.

This means that if you ever meet a gorilla or chimpanzee in the forest, when you go to shake hands there won’t be confusion as to which to extend.

Technorati Links: evolution, language

One replicated study I recall discovered that a greater difference in the length of pointer and middle fingers in men and women correlates with higher testosterone levels. And higher testosterone levels are associated with a greater propensity for aggressive behavior.

Seems I remembered wrong. The fingers in question are the fourth and the second fingers (pointer and ring). An article I read yesterday set my knowledge straight and advanced it. In Hormone that affects finger length key to social behavior I read of these three clues to the potential influence of hormones on primate behavior:

1. Finger ratios do not change very much after birth and appear to tell us something about how very early androgens affect adult behaviour, particularly behaviour linked to mating and reproduction.

2. The team found that Old World monkeys, such as baboons and rhesus macaques, have a longer fourth finger in comparison to the second finger, which suggests that they have been exposed to high levels of prenatal androgens. These species tend to be highly competitive and promiscuous, which suggests that exposure to a lot of androgens before birth could be linked to the expression of this behaviour.

3. Lower androgen levels could help explain why Great Apes show high levels of male cooperation and tolerance.

From the research into testosterone and hand measurements, I think I would be justified in proposing that, to divine the general traits of a species, “reading” the relative length of their fingers would be more productive than reading their palms.

Interesting stuff. I hope in the future more studies will be conducted on the influence of both “male” and “female” hormones on human behavior.

Technorati Links: psychology, testosterone

Recent research into chimpanzee social behavior has highlighted both a similarity and a difference. In the news release, Chimpanzees Help Each Other On Request But Not Voluntarily I learned,

[A] new study by researchers at the Primate Research Institute (PRI) and the Wildlife Research Center (WRC) of Kyoto University shows that chimpanzees altruistically help conspecifics, even in the absence of direct personal gain or immediate reciprocation, although the chimpanzees were much more likely to help each other upon request than voluntarily.

Those animals and their animal behavior! They are somewhat like us. Quite a bit, actually. Chimpanzees helping other chimpanzees, “even when there was no hope of reciprocation from the partner (as in experiment 2) and even when the two animals were unrelated.”

How is the human/chimp altruism glass half-empty? Chimps usually need some sort of prompting before they come to the aid of another. One individual gestures to another; and the other complies. Humans, meanwhile — with their robustly developed cognitive capacity called “theory of mind” (the ability to infer the mental states of others, including intentions) — very frequently need no such prompting. For example: You are walking down a hallway and a stranger ahead of you drops something. How often do you alert him/her and/or retrieve it, without prompting? For most people, often.

Just yesterday I engaged in behavior that could have been part of a naturalistic experiment in human altruism. I was exiting the post office and noticed a person approaching the adjacent glass entry door. He had an armload of boxes. Without thinking I took a step and reached toward the entry door handle. The man said, “I got it, thanks,” and waved to me with a free hand beneath cradled boxes.

Upon thinking about it now, I had nothing to gain by doing this. Or did I? I didn’t know the man, and judging by his triple-x belt size, yellow teeth, and grease-smudged eyeglass lenses, he is not the type I view as a potential friend. So why the natural reaction? I saw someone needing help, so I helped. Period.

Is this natural inclination evidence of a primate mind that evolved in smaller groups sizes, now living in social environments where peaceably mixing with strangers is a common, “unnatural,” occurrence?

Speculative explanations aside, the divergence between human and chimpanzee behavior remains. You could say that our nature is not just that of a social primate, but of a social primate par excellence.

Technorati Links: evolutionary psychology

Is it any surprise, then, that new research into the cognitive abilities of another primate species, the cotton-top tamarin, has revealed that they, too, have individuals that sit in the front of the class and those that don’t know where the front of the class is. So to speak.

Testing for broad cognitive ability, the researchers identified high, middle, and low performing monkeys, determined by a general intelligence score. General intelligence, or “g,” is a hallmark of human cognition, often described as similar to IQ. The effect of “g” in primates may offer insight into the evolution of human general intelligence.

How did the researchers determine they had actually measured “general intelligence”? Good question. Here’s how:

Monkeys with higher “g” scores tended to outperform monkeys with lower scores across the various subtasks in the cognitive task battery.

In other words, individual monkeys that were fast at solving the banana-shaped Rubik’s Cube problem (I’m making this up) also tended to thwart their cohorts in the backgammon competition. Or something.

I wonder, is there such a thing as a brilliant butterfly? A dull goldfish?

Technorati Links: intelligence, primates