You know Darwin sailed, famously, on The Beagle. But did you know he also sailed on another boat? Check it out.
More Bird Body Part Blogging: Spurs and blades on the wings of jacanas, lapwings, sheathbills and archaeotrogonids (clubs, spurs, spikes and claws part II)
A colleague and grad student of mine, Rob, just sent me the following question, slightly edited here:
A student in my intro class asked me a good question the other day to which I had no answer. When did smiling cease to be a threat gesture? I have a couple of ideas. One is that with reduced canines, smiling became a way to say “look, I have small canines, I am not a threat to you.” The other is that smiling is based more on a “fear-grin” than a threat. Under this idea, smiling might have been a way of showing deference to others. If everyone shows deference, it would be egalitarian, until the one guy comes along who never smiles. Maybe that’s why bosses often don’t smile. … let me know when you have some free time to have lunch. Tuesdays and
Wed’s probably work best for me.
Good question, and good ideas as to a possible answer. I have a couple of other ideas to contribute….
(a repost)
Dare I say “It’s too bad that smiles don’t fossilize…” But really, if we started digging up smiles, that might make palaeoanthropology too weird to contemplate and fewer people would go into the field.
Since primates seem to use facial gestures like smiles and yawns to communicate emotional state and to negotiate social status, a comparative approach is reasonable. However, human emotions have been incorporated into a set of social relations that are very derived so this is difficult.
In The Face: A Natural History
Smiling is innate in infants, and has obvious social implications in humans, but the role and nature of the smile … as far as what the mouth is doing while smiling … seem to have culturally bound variation.
Have you seen the movie Platoon? For a few years, some time before that movie came out, I had the pleasure of working with a number of Viet Nam vets (doing archaeology and historical research). I heard a number of stories from them over the years, and Platoon, interestingly, seemed to me to be a catalog of horrors experienced by most of the ground troops who spent a fair amount of time in that conflict. One of the events that happens in the movie involves a raid on a village suspected of harboring “Viet Cong” or stashing weapons. The Marines corner a young man and insist that he tell them where the bad guys and/or weapons are hidden. The young man is totally freaked out, but appears to be smiling at the Marines. This enrages one of the Marines, who eventually kills him.
What the Marine missed is that in the culture of that region, there is a facial expression that Westerners will often interpret as as smile, but it is in fact a grimace. The corners of the mouth are turned up and the teeth are showing, but there is nothing happy going on at all. We do see this in Western settings as well, just not as often. My daughter was perplexed a few months back when one of her friends seemed to be smiling while talking about the death of her father a day or two earlier. The girl’s emotions were clearly showing, but a negative expression appeared as a smile (at least that is what I think was happening).
The mouth-smile of primates is, in fact, usually a grimace and not a happy thing (as you point out). I think primates do different things to show that they are happy, and smiling may not be on the list.
A hard core evolutionary psychologists might suggest that s smile shows a state of health by showing a complete set of teeth, indicating normal development during childhood and that you have spent a life not making other people mad at you enough to knock out a few teeth.
I’m not sure I like the canine/no canine idea too much because that is a display that operates across broad phylogenetic differences. Consider analogues to this argument with other physical traits. Every time a whale pirouettes in the water it is demonstrating that it does not have those ancient land-mammal legs any more. I don’t think the other whales would be impressed. (I admit that might be an extreme example).
But here is what I think is the most important point: An evolutionary theory about smiling has to take into account the whole face (and perhaps more) and not just the lips and teeth. Look at this picture:
You can tell that this person is smiling and you can’t see her mouth. The eyes give it away. Meanwhile, you can tell that this person is not smiling:
By the way, the upper photo is a professional model. She is not necessarily happy, but she is really smiling. She is truly smiling because she is looking at something she truly loves (the camera). The ability to do this is what separates the professionals from the rest of us who always look like we are faking it when the person taking the picture with one of those horrid PHS digital cameras takes nine minutes to press the button while we stand there waiting.
Expressions can be important. They can even tell you what a member of another species is thinking, as has been demonstrated over and over again by the insightful LOL cat movement:
As for lunch, Wednesdays are good for me.
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| Efe people Ituri Forest Anthrophoto is an excellent source for anthropology stock photos |
There have been many studies of what impresses us about members of the opposite sex, but to my knowledge these studies are largely centered on Western societies, and never of foragers. There has been consideration of this issue, but no large scale surveys. One of the reasons for this is that you can’t do large scale surveys in so-called “small scale” societies, because there are just not enough people.
But I can provide a few insights on what might be impressive to the ladies (things about men) in forager societies. Keep in mind, however, that this is strictly speculation, though informed speculation.
I had previously talked about sharing, and here I’d like to expand on one aspect of sharing, the so called “distribution and redistribution system,” and it’s meaning in relation to courting.
There is a pattern that has been observed in virtually all forager groups, whereby men divide up the spoils of the hunt in a certain, largely ritualized, way, then pass these packages of meat over to the women, who then redistribute the meat in a manner commensurate with the needs of members of the group. I’d like to describe how this works specifically with the Efe Pygmies as an exemplar for foragers in general. Many aspects of what I’m describing here are nearly universal among foragers. Moreover, I’m going to specifically talk about “group hunting” when several men are involved in one cooperative hunting episode. However, the principles involved here actually apply to other forms of hunting as well, to varying degrees.
The most common Efe group hunt is called “mota.” In this method of hunting, a number of men spread out in the forest to surround an area, with one man (the “beater”) going to the center of this area with one or more dogs. The dogs are released by the beater, sent out into this area and called back again and again. Game that is roused by the dogs are then subject to being shot at with arrows by the archers who had previously spread out. If an animal is hit, help from other hunters or from the dogs may be solicited, and the animal run to ground and dispatched.
The animals are usually carried back to near the camp (these animals are small and can be carried whole by one person) where two people (not the hunter himself) butcher the animal. The animal is cut into standard pieces: The head, each front limb and body quarter, each hind limb and body quarter, and an area of the middle of the animal including the last few ribs (this is considered to be the “special” part, possibly because it contains the backstrap/loin meat).
Sometimes the head is left with one of the forelimbs. Sometimes the back two quarters are kept together.
Each of these parts is then given to a different man depending on a set of rules that specify a link between a man’s role in obtaining this meat and a particular body part. The rules vary from place to place and presumably time to time in Pygmydom, but it may be, for instance, that the man who called and organized the hunt, usually the beater, gets the front left limb, the guy who trained/owned the dog that ran down the animal a back quarter, etc. The only really consistent thing across the different rule sets is that there is usually a key hunter (the person who first shot the animal, for instance) who gets this middle back piece.
One striking aspect of this is that efforts are made and culturally determined to ensure that a lot of people were involved in the kill of any animal, even by a lone hunter. Here are some of the rules that ensure this:
1) No man carries his own arrows. The metal tipped arrows the Pygmies use for hunting ground animals are each made by someone else. Therefore, if you shoot an animal, another man besides yourself was “involved.”
2) The dog is owned by a particular person.
3) A ritual fire is burned before the hunt by a particular person.
4) The beater is a particular person. These three — dog owner, fire burner, and beater, may be the same person, two people, or three people.
5) The animal is supposed to be butchered by individuals other than the prime hunter.
6) The animal is supposed to be butchered OUTSIDE OF CAMP (even it it runs into camp and dies there … it would be dragged outside of the camp for butchery) by TWO people. (Not one, even though that would be possible.)
7) Oh, then there is the guy who shot the animal!
All of this ensures that even if you hunt alone, multiple people will be involved.
Now, we are guessing that the ladies are concerned with the hunting, and the meat, and thus with the quality of hunters, in some way. So the first approximation is that the women measure the hunting ability of the men and take this into account during courtship. Previous studies have not supported this idea.
One idea that may work is that the ladies pay attention to the man’s package. What I mean by this, is they notice what package of meat he comes in to the camp with, which would give the woman an idea of his role in the hunt, and thus information to assess his hunting ability.
However, there is a catch to this: I have observed that the men hardly ever walk into camp with the pieces of meat that actually represents what they actually did for the hunt. If this is a signal, the men are being dishonest.
One idea that may work to get past this problem is that the men are being dishonest but the women can’t figure this out. If the men came into camp and verbally claimed a certain role in the hunt, the women (and others) could easily detect the lie. But by simply carrying this package of meat into camp and not saying anything, and handing this meat over to a particular woman (someone they are trying to impress) they are not as easily caught in the lie.
However, I don’t believe this for a second. I think the women would still be able to tell who is being honest, or at the very least, the women would understand that the whole exercise is a charade, and simply not use this as information in choosing a mate.
So this brings us to one more idea that may help understand this, and I think the explanation for what is going on.
Suppose a young man is a typical hunter, and is courting a prospective mate who is hanging around in camp (visiting her sister, perhaps). As a typical hunter, there really is not much he can do to increase his role in the hunt, other than simply showing up and doing his job. Most of the hunters are excellent shots, and although older guys do better than younger guys, how you do over a series of a few hunts is also very largely a matter of luck.
But suppose this young guy comes into camp each day for two or three days in a row with a real nice package, something that would indicate an important role in the hunt. But he did not earn this package by what he did during the hunt. Instead, his male relatives and friends give him the package, knowing that he’s interested in the woman likely to be in camp on their return.
This indicates nothing about his hunting ability to the woman. But it does indicate something much more important: It indicates that he is not a complete jerk. It indicates that he has friends, that they will give him a break, and that he is part of a coalition of cooperative foragers. That is what makes a good mate.
Indeed, if women made choices among men based hunting ability, then they would be making poor choices. First, hunting ability might be important, but many other things are important as well. Second, as noted above, most forager men are pretty good at hunting. How well someone does is more a matter of luck than ability. So, hunting is not a trait that varies meaningfully or that can be assessed accurately.
Having said that, among the Efe, there is a form of hunting that is done by only some men, and that produces on its own about the same amount of meat as all the other hunting efforts combined, on an annual basis. This is the killing of an elephant. It is hard to do, far more dangerous than other forms of hunting, and highly productive. I suspect a lot of women would not be interested in such a mate. The guy must be crazy, after all. But some are. It is very rare to find Efe men with more than one wife (it is allowed but very uncommon). An Efe man does not usually have more than one wife, but when he does, it is often because he is an elephant hunter.
An Evolutionary View of Humans 1: Introduction
An Evolutionary View of Humans 2: Sleep
An Evolutionary View of Humans 3: Remembering Names
An Evolutionary View of Humans 4: Sharing
An Evolutionary View of Humans 5: The Opposite Sex
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| Efe people Ituri Forest Anthrophoto is an excellent source for anthropology stock photos |
One of the biggest differences between our nearest living relatives (The common chimpanzee, Pan troglodytes) and humans is our unique sense of the importance of a social contract. We have a concept of ownership, possession, exclusivity of access, etc. when it comes to material goods such as tools or resources, and of course, sexual relationships. It has been argued that this is a feature that can be found in primates. In a classic series of experiments done by Kummer with baboons, he showed that one male baboon perceived an ongoing sexual liaison between another male and a particular female. As long as the paired male was in sight, the focal baboon would not make sexual advances towards the paired female even though she was in a state of sexual receptivity. This was the case even when the focal male and the paired female were enclosed in a cage together, with the paired female enclosed in a different cage a safe distance away. Similar observations have been made in other primates including chimpanzees in captivity and in the wild.
However the presence of a vague ability to perceive danger — that you will likely be severely attacked by a large male under certain circumstances — is expected in social primates. What Kummer’s experiment may really demonstrate is that baboons don’t “get” cages.
The evolution of a sophisticated mechanism or set of mechanisms in hominids (humans and their upright ancestors) that elaborates on this capacity is what we would expect from an evolutionary perspective. We are upright using our hind limbs mainly for locomotion, and thus different from other apes, but at the same time the nature of our uprightedness (that we can also use overhead bars and straps on a bus or subway for stability, for instance) is a feature of our positional behavior that relates directly to the fact that apes tend to suspend below branches rather than walk atop them (as to Old World monkeys).
In other words, I don’t think that a trait observed in one species is not unique and not the result of adaptive evolution just because a mild form of the trait is observed in other closely related form. Such a situation — total uniqueness — is simply not expected most of the time.
Tropical and subtropical human forager groups all exhibit what we call a “sharing ethic.” Typically, this is manifest as social rules whereby if one person asks another for a particular thing, it is simply given. Both stinginess and gloating (over possession of something) are culturally proscribed. A person is judged by others on the basis of many things, but near the top of the list is a strong sharing ethic. It is even likely that people show off by trying to be the better sharer, and in some cases, the better not-shower-offer.
From a biological perspective it is thought that sharing is necessary in foraging societies because the nature of foraging is such that no one individual can maintain a sufficiently consistent food supply over medium to long term on the basis of their own efforts. Only by division of labor (often by sex) and sharing, whereby one person with a surplus distributes that surplus one day, and in return benefits from the largess of others on other days, can an individual avoid periods of starvation that would sometimes last days or weeks (and thus possibly be fatal).
This argument, however, is weak on its own, because most (all?) tropical and subtropical foragers do have access most of the time to resources that are consistent over long periods. In most of these groups, females are able to obtain in a given day sufficient food for their immediate needs and the needs of their offspring. Males, on the other hand, tend to forage for resources that result in occasional abundance dispersed among days of an inadequate supply. Were humans to stop sharing in these groups, this could work out as long as everybody (males included) foraged in the female style.
However, the resources that males tend to obtain from the wild (mainly meat from hunting), despite their irregularity, may serve a critically important role – or more than one role. For example, basic cellular function, especially as related to growth and the immune system, require the synthesis of many proteins that are built from amino acids. Some of these amino acids are synthesized in one’s own cells, others are not and must be ingested … typically in the form of proteins in a variety of plant foods as well as animal foods. The amino acids are not interchangeable. Almost all proteins are made from a list of 20 amino acids that occur in varying degrees of abundance in various plant foods. If you eat only plant foods, there will always be one amino acid that is the rarest of those needed, so you must ingest a larger than optimal quantity of foods. But if you eat meat, you are ingesting a perfectly balanced set of amino acids. In other words, a very efficient way of growing and in certain ways maintaining your body is to eat other animal bodies.
So, it may turn out that the highly variable sources of “balanced” proteins … mainly meat from hunting … are a critical resource for this (and other) reasons. So while day to day energy needs cannot be met among these forager groups from hunting (that comes mainly from the plant foods), the needs of growth and immune system function and general cellular processes can be met with this variable food supply. But only if it is shared.
The problem this presents is actually psychological (or maybe I should just say neurological … brain based). Apes don’t share much. When chimpanzees forage — and they typically forage for relatively rare, high quality foods — they benefit by foraging alone because this reduces competition with other chimpanzees. They do not bring the food they find to any other place than where they found it in order to consume it.
In contrast, human foragers do two critically important things. First, they bring much of the food they forage to a central place — the forager “camp” as we call it. Since all the foragers in a given group (by definition) live in the same camp, they are therefore bringing this food into direct competition with other foragers. If they were chimps, the dominant chimps would just take the food from the lower ranked chimps, or small coalitions of cooperating individuals (usually males) would take any of the food they wanted from any of the other chimps.
The second thing foragers do is to process much of this food. This processing is often essential to make these food items edible. In other words, human foragers are finding items (plant parts) that are not edible by humans, and thus constitute a kind of VERY low quality food (zero or near zero caloric value) and by processing — including cooking with fire — turn this stuff into medium or high quality food.
The only way to do this second thing (turning the inedible into the edible) is to do the first thing, to have a central place foraging style. And the only way to do this is to have a social ethic that manages the concepts of possession, ownership, sharing, and so on.
How does this ethic emerge in an individual? A little introspection and reference to experience can help answer that question. Sharing, being fair (the opposite of “cheating”), a capacity to learn and live by certain social ethics and so on, emerge over several years in children with the continuous, time consuming, and energetically costly efforts of adults.
What are the social mechanisms that are at work in this aspect of childrearing?
Are there ways in which adults, who are at a stage in their lives when they are looking for possible mates, evaluate each other with respect to these behavioral qualities? Are there aspects of the human dating/mating/marriage rituals and patterns that demonstrate this?
Are there ways in which adults demonstrate these qualities, and if so, how do others ascertain if these demonstrations are false vs. honest indicators of a sharing ethic?
How does this play out in social relationships other than mating/marriage?
Are there conditions in which sharing is the inappropriate behavior? If so, how do individuals or subsets of society balance a sharing ethic and what might be called a selfish ethic?
Do the manifestation of these behaviors vary across age and gender, or social class?
Humans are different from chimps in these critical aspects of behavior, and these differences are manifest in both ecological and reproductive aspects of human culture and society. Modern foragers demonstrate the human condition, and the way in which these problems have been solved through adaptive behaviors. What kinds of problems emerge in other kinds of human societies that have emerged only recently in human prehistory, such as agricultural societies where the value of land on which food is grown, or the efforts put into crop tending, create a new kind of resource — immobile, big, and vulnerable? What kinds of problems emerge in pastoral (i.e., cattle-keeping societies) in which the key resource is potentially VERY mobile, but still big and vulnerable? What are the resources that Western Industrial societies rely on and how is that managed? In other words, what would a list of evolutionary discordances — differences between the normal foraging way of life and other ways of life — look like?
An Evolutionary View of Humans 1: Introduction
An Evolutionary View of Humans 2: Sleep
An Evolutionary View of Humans 3: Remembering Names
An Evolutionary View of Humans 4: Sharing
An Evolutionary View of Humans 5: The Opposite Sex
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| Efe people Ituri Forest Anthrophoto is an excellent source for anthropology stock photos |
How good are you at remembering names? If you are really good … if you can hear someone’s name once and always remember it … you have a calling as a politician. If you would otherwise suck as a politician, but are good at explaining things, maybe a job as a teacher (but that requires other skills as well). In any event, you are a rare bird.
Humans have typically lived in small groups. This is especially true of foragers. Not only are these groups fairly small, but they are also fairly stable. The movement that does occur between groups is typically restricted to a larger “meta-group” consisting of a few different small groups. In other words, if you are a forager sitting around with the people you live with … the people in your “residence group” as we call it … the person sitting across from you is most likely someone whom you’ve known all your life (or visa versa, depending on your relative age).
Just as importantly, the total number of people you will know during your entire life well may stay in the hundreds. That’s total. Compare that to your own “Western” experience. Count the people in each neighborhood you’ve ever lived in (whom you knew), the people in all the different grades of school you’ve been in, and the people at all the different workplaces you’ve worked in. That is probably a large number. If it is a small number, then you don’t’ get out enough. You should get out more. At least go see a movie or something…
The point of this is that remembering names is something we have not evolved to do well for at least two reasons: 1) Everybody you run into is someone you already know (most of the time) and 2) Everybody you know is someone you’ve known for a long time, so you get a long time to remember their names.
There may be another aspect of this as well, but I simply do not know how broadly this applies across forager societies. In at least some societies, it is typical to use personal names only rarely. The day to day conversation among people in many camps and villages of which I am aware makes reference to people by kinship or other generic terms, not names. During my research in the Ituri, I participated in a long term project (as a trained helper) in which we collected demographic and physical data from a large sample of people. This was something all participants in the project agreed to do in order to maintain and grow a large and important data base. As part of this a couple of us would show up in some camp (of Efe) or village (of the horticultural Lese people in the same area) and run down the list, checking off who was still in the village, getting a body weight, a few other bits of information, etc.
There were times when I would ask, say, Joe, who that person over there was (to avoid the embarrassment of not knowing) and Joe would say “oh, that’s my sister.” Then I would say “what’s her name, you have two sisters” and Joe would yell across the compound “Hey dad, what’s my older sister’s name…”
Wow.
This would be partly because Joe would normally refer to his sister as “my sister” rather than by her name, and partly because nine years ago, Joe’s sister had a baby boy named, say, Frank, and has been since known as “mother of Frank.”
(There are of course other occasions, well known in anthropological circles, where a person cannot say a certain other person’s name. Maybe your culture prohibits you from naming an inlaw, for instance. I am not talking about this situation here.)
The point is that the Western concept of personal names and how they are used is fairly culturally specific. What seems like a common deficit, the general difficulty we have in remembering names when we first hear them, is actually quite expected.
There reason you can’t remember anyone’s name is because there are too many names to remember and you haven’t had a chance yet. And evolution. Not your fault.
An Evolutionary View of Humans 1: Introduction
An Evolutionary View of Humans 2: Sleep
An Evolutionary View of Humans 3: Remembering Names
An Evolutionary View of Humans 4: Sharing
An Evolutionary View of Humans 5: The Opposite Sex
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| Efe people Ituri Forest Anthrophoto is an excellent source for anthropology stock photos |
There has been much recent discussion on sleep in the blogosphere, and everyone, especially those who sometimes have trouble sleeping, is interested in so called sleep disorders.
My understanding of modern sleep disorder theory is the following (very oversimplified): Each person has a “normal” amount of sleep that they seem to need each night. “Better” sleep is uninterrupted. You will feel lousy if you don’t get your sleep. However, if you miss the “normal” amount of sleep several nights in a row, you only need one “good night’s sleep” to totally readjust and get back to feeling normal again. (You don’t have to make up all the hours you missed … heavens, there IS a free lunch!)
Most tropical or subtropical foragers live in flimsy dwellings (or no dwelling on some nights) clustered tightly together, so, for instance if one person snores everybody hears it (though snoring is rare among foragers in my experience). My point is simply that everyone is physically close.
Even in warm areas, it gets cold at night, so there are fires. Fires have the upside of making you warm, but a couple of downsides as well. First, they need to be tended frequently. Second, adults and especially children can fall or roll into them and get badly burned.
A typical night with the Efe is, I strongly suspect, typical of any night with any tropical or subtropical forager group. At any given moment in time, somebody is asleep and somebody is awake. Those who are awake are often talking. Sometimes they are talking to each other, but often they are just talking. Telling a story that someone may or may not be interested in. I suspect that part of the constant noise making (and what may make Africa different from Australia, by the way, if you know about Australian forager ethnography) is that you don’t want to be too quiet for too long else wandering dangerous animals …. a leopard, a suid, an elephant … may stumble into your camp and cause trouble.
The person or persons who is/are awake shifts throughout then night. It is not systematic … people are not really keeping watch … it just seems to happen. Individuals sleep when they are comfortable, and become uncomfortable as the fire cools, wake up, adjust the fire, and either stay up for a while or fall back to sleep. If one child is keeping his or her family awake, this affects the entire group. And so on.
Naps during the day (as you might expect since everybody gets a poor night’s sleep by Western standards every night) are common.
Here it is in a nutshell. The Efe, and I again suspect this is typical for foragers, spend the entire 24 hour cycle sometimes awake and sometimes asleep. During the night, “asleep” is more common than “awake” and during the day “awake” is more common than “asleep.” To foragers, it’s all napping.
One could criticize this description by pointing out how it conflicts with modern medical views of sleep. But you would be wrong. It is the case that modern medical views of sleep need to be adjusted to take into account the realties of what humans have probably always done for hundreds of thousands of years (since the first control of fire, perhaps).
An Evolutionary View of Humans 1: Introduction
An Evolutionary View of Humans 2: Sleep
An Evolutionary View of Humans 3: Remembering Names
An Evolutionary View of Humans 4: Sharing
An Evolutionary View of Humans 5: The Opposite Sex
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| Efe people Ituri Forest Anthrophoto is an excellent source for anthropology stock photos |
Humans have been indistinguishable as far as the fossil record shows from today’s Homo sapiens for a minimum of about 120,000 years. Bones of Homo sapiens from back this far fit into the range of modern humans. But the archaeological record suggests that our species – just as it is today – goes back farther. The kind of material culture that the 120,000 year old humans (in Africa) had goes back to 250,000 years. But some of the key aspects of that material culture … mainly in the way stone tools are made … go back even farther, perhaps between 350,000 and 500,000 years, in southern Africa.
(Interesting aside: People often wonder if Neanderthals evolved into modern humans. That questions seems a little dumb when we consider that the earliest modern humans predate the earliest Neanderthals.)
Humans invented agriculture (domestic plants and animals) only about 10,000 years ago or so, and at that time some groups started to live in permanent settlements. But even so, many humans continued to practice hunting and gathering as their only, or at least primary, means of subsistence. A mere 4 or 5 thousand years ago, half of the human species probably lived this way.
In other words, humans evolved as hunter-gatherers and have mostly been hunter-gatherers for for more than Continue reading An Evolutionary View of Humans 1: Introduction
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In approaching evolutionary puzzles it is helpful to have certain thought-tools in mind. These are approaches to life, literally, including issues of survival, mating, and so on. My grad school advisor, Irv DeVore. used to tell his students to imagine what an animal would be thinking on first waking up in the morning (or evening if nocturnal) to get through the day: “How will I find food today? …. how will I avoid being someone else’s food? … Will I find a mate, or will one find me? …” (In writing that just now I can’t help but think DeVore may have been cribbing Jack London just a little.)
Anyway, here are some rules of thumb useful for thinking about both physical and behavioral systems.
Romer’s Rule. Romer’s rule is simply stated as “A frog is simply a fish trying desperately to remain a fish” Continue reading How to think like an evolving organism.
This is the first of a series of posts on the biology of gender. This is a research interest of mine, and generally has a big part in my teaching as well.
Behavioral biology seeks to understand behavior in an evolutionary framework. The widely held central dogma of evolutionary biology is that selection works on allele frequencies. This leads to simple models of behavior that assume behavior is acted on by selection, and that underlying alleles are selected for or against over time. This sort of logic can be seen in biological racist doctrine, sexist racist doctrine, and more politically ambiguous research such as the famous twin studies, and about every other article in journals such as “Evolution and Human Behavior” (not that I have anything against that journal in particular … but … well, you’ll see…)
When thinking about the biology of behavior, a common guiding principle is that the stronger the effect, the “more biological” it is. There is a certain logic to this. If a certain aspect of, say, human behavior is observed over and over again, across cultures, and it is shown to persist even when social, economic, or cultural influences seem to work against it, then it makes sense that it is somehow predetermined. Continue reading The Biology of Sex and Gender: What’s in a name?
I was recently looking at a practice AP biology test question on evolution, and sparing you the details, I found it interesting that two of the four parts dealt with genetic variation and speciation in such a way that it was difficult to tell them apart. As expected, students who answered these questions got confused as well, and tended to give perfectly good answers to Part B, but unfortunately, this was their answer to Part A. By the time they got to Part B they seemed a little confused, perhaps realizing that there was some overlap and conflation of concepts.
Inter and intra-specific variation is probably patterned such that the sum of variation among several species is greater than the partitioned variation within a given species. That’s pretty obvious.
(Just in case it is not: Imagine measuring the mass of several elephants. The variation can be represented by the standard deviation, range, or whatever you like, among your measurements. It is such and such. Now do the same thing with a bunch of mice. Again, you have some measure of variation. Now do it for the mice and elephants combined. Here, the variation will be larger than for either. This is not the same as if you want to compare variation or patterns of variation between mice and elephants. Do do that, you need to scale the variation, say by using the coefficient of variation. In this case, combining the coefficients of variation might show less variation when combined than for either group simply because of sample size effects. But what I’m talking about here is total variation. Mice are tiny, elephants are huge, so their total size variation runs Continue reading Of skinks and monkeys
Why is hunting thought to be a key factor in human evolution? Partly because it was once widely believed that among the primates, only humans ate a fair amount of meat (not counting insects). If human hunting and meat consumption was unique among primates, then the evolution and effects of this behavior could easily be understood as vitally important. Moreover, a lot of fieldwork and thinking about human evolution centered on Europe, where cave paintings of animals were common, with some hunting themes seemingly represented in these paintings.
Of course, the uniqueness of human hunting behavior is now understood to be a gross overstatement. There is hunting of mammals and the like by several primates, and in particular, chimpanzee hunting (mainly of monkeys) is fairly common.
We now know that almost all of the important events that have happened in human evolution (since the chimp-human split) happened in Africa, and that the European record, while interesting, is not the primary record for these events. Therefore, one would think that the European bias would be somewhat reduced in current thinking (the fact that it is not is of great interest, but I’ll not go into that here!).
But I think the most important reason for hunting taking center stage in the study of human evolution, to what appears to be an unjustified level, has to do with the nature of “Man” and the nature of “Hunting.”
Have you ever been hunting, or been along with others while they did so? I’ve accompanied both North American game hunters (armed with firearms) and Efe foragers (armed with arrows and spears). Most of my time has been in the latter pursuit, and in a few instances, I joined the hunt not just as an observer but as a participant/observer.
I don’t think hunting is a normal human activity in the same way that hunting is a normal lion activity, or a normal wolf activity. Humans seem to react to hunting in a very powerful way, similar to how humans react to violence in general (and hunting seems to be fairly violent) or to certain kinds of sporting events (as observer or as participant). A lot of yelling and screaming and jumping around can ensue under certain conditions. Yes, most forager groups disdain bragging and avoid giving too much credit to any individual for being a great hunter, but the visceral reaction to, say, a near miss or to those moments when the hunted animal turns on the hunter (usually only briefly and to the animal’s final chagrin), is powerful and can’t be covered up or put into the background by cultural norms of modesty.
Is this the case in humans? There is no way to know this at this time. There certainly are groups of human foragers (in the ethnographic present) who rely so much on meat that hunting is basically a form of subsistence, no matter what other function it may have. Even when plant foods are abundant, meat is still important to almost every group of forager (and non-forager, likely) as a source of “complete proteins.” All traditional human hunting is imbued with ritual and ceremony that exceeds that generally linked with gathering. So in the end, there is evidence that hunting can be and often is an ecologically important activity for human foragers. There is also evidence that hunting is (probably) always an important social activity, mainly among men.
[Ask me later: Why a photograph of the Afrikaans Language Monument in this particular place, at this particular time…]
When a 19th or 20th century guy archaeologist holds a beautifully made, often phallic-shaped obsidian spearhead in his hands, feeling it’s heft and running his fingers along the still sharp, elongated, stone-hard edge, he is bonding with another guy, of a much earlier time period, who could probably have killed his quarry just as effectively with a sharp stick, but opted instead to produce, carry around, display, and use this really cool piece of gear. So it’s a guy thing, and it’s a gear thing. It’s sort of a guys-with-gear thing.
Hunting isn’t likely the driving force in human evolutionary change, but it can certainly be an important human activity that is related to human evolutionary change.
One final brief note on something to be addressed at another time: The assumption that hunting by men is central to human evolution has led many to assume that hunting drove the evolution of tool use, and thus, tool use is a male thing. This contradicts the best evidence we have about technology in primates, which suggests that females, not males, are the tool makers, tool users, and the teachers (or at least facilitaters) who pass this ability on to subsequent generations. So, gear, it turns out, may be more of a girl thing after all.
In considering the evolution of human language, I think it is helpful to contrast these two books, and the ideas presented in them:
Terrence Deacon’s “<The Symbolic Species: The Co-evolution of Language and the Brain
and
Stephen Pinker’s “The Language Instinct: How the Mind Creates Language (P.S.)
Neither book is exceptionally new, and in fact, Pinker has cranked out a number of books since The Language Instinct. However, I think The Language Instinct is the best of Pinker’s volumes for this discussion. In it, he lays out the basic evolutionary psychology argument in a way that is most directly contrasted with the ideas in Deacon’s. Also, The Language Instinct has a great chapter called (if memory serves) “The Language Mavens” which is worth reading whether or not you agree with or even like the rest of Pinker’s book.
Continue reading Evolution of Language: Deacon vs. Pinker