the evolving mind

“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

The behaviors we acquire through enculturation feel right, they feel natural. To shake someone’s hand upon meeting him or her feels natural. At least for people in most cultures. Waving goodbye . . . eating with a fork while seated at a table . . . waiting in line . . . wearing pants . . . and on and on the list could go. Interrupt and disrupt these behaviors or travel to a place where they aren’t the norm . . . and your emotions will tell you “something is off.”

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

While I am a huge fan of the anthropology and primatology fields, and I have no qualms with tentative parallels drawn between other species’ behavior and our own (evolutionary psychology), I am first and foremost a skeptic. And so the news of some recent chimpanzee research first piqued my interest, then got me grunting in disapproval.

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

Certainly humans are more civilized than chimpanzees. At times, sure, it doesn’t seem by much. Just prior to typing this I was listening to a blues station that played a song with these lyrics: You can have my husband but don’t mess with my man. Get it? Our kind can certainly be sexual opportunists. Other “brutish” human behaviors readily come to mind: warfare, xenophobia, school yard bullying, soccer riots, paid prostitution for sex, Valentine candies for sex, etc. Maybe it’s just me, but most television programming would make more sense if the actors were covered with fur. Oh yah, now I can see what’s really going on.

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.

Continue Reading »

Technorati Links: evolutionary psychology, primates

While chimpanzees build no churches in which they bow down to an invisible alpha, they do engage in some behaviors that could be considered pre-religious. For example, chimpanzees will make threat displays at an approaching thunderstorm, as if attempting to bluff it away. In this case they have extended a natural propensity beyond the domain of real agents, where a threat might produce results, to the domain of non-agents (storms), where the threat will absolutely not produce results in the form of influencing the behavior of the target entity.

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 some circumstances the application of evolutionary-psychology thinking can be as silly as trying to find the primate precursor to the behavior of a piloting an airplane. Did swinging from trees help prepare humans for steering a Boeing 747 through 3-dimensional skies? Isn’t it obvious that peeling a banana is the antecedent to opening a flight log?

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.

Continue Reading »

Technorati Links: evolutionary psychology, primatology

Almost one year ago to the day I made a post about research into the “handedness” of gorillas: Shake Hands with that Gorilla. That primate species, it seems, has a preference for using its right arm/hand. New research appearing in the Jan 2010 issue of Cortex relates this finding on chimpanzee handedness:

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

My bad. In a recent post, Unconscious Influences and the Faces of Homosexual and Aggressive Behavior, I wrote -

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

In terms of the similarities between humans and other great apes, particularly chimpanzees, you could say that I have been guilty of focusing almost exclusively on the part of the glass that is half-full. (Or is it 98% full? I guess it depends on whether the stuff in the glass is behavior or genes.) But there certainly is that empty part — those ways in which humans and our close primate relatives diverge and differ.

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

Human apes are intelligent. But they aren’t equally intelligent. While some can, say, learn a second and third language with relative ease, others never fully master their first. And while some have no difficulties mentally computing the volume of stale air in a doctor’s office, other’s need a handy, wallet-sized chart to help them determine how much to tip their waitress.

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