Category Archives: Evolutionary Biology

Gene Therapy Is Starting To Be A Real Thing

Today, the an FDA advisory committee recommended that the FDA approve full clinical trials for a type of gene therapy that addresses a rare genetic condition causing deterioration of the retina. This is found in 8.6×105 of people world wide, so not many. the therapy involves injecting a virus bearing the preferred copy of the gene, the non-broken allele, into the eyeball, where the new gene somehow reduces, stops, and seemingly reverses, the deterioration.

The therapy was previously looked at in a preliminary study with a small sample of people. Here is the abstract from that study: Continue reading Gene Therapy Is Starting To Be A Real Thing

How long is a human generation?

How long is a generation, you ask?

Short Answer: 25 years, but a generation ago it was 20 years.

Long answer: It depends on what you mean by generation.

In US-biased Western culture there is a Biological Generation, the Dynamic Generation, the somewhat different Familial Generation, what is sometimes called a Continue reading How long is a human generation?

Aging in men: An evolutionary perspective

Many years ago, Mel Konner, Marjorie shostak, and Boyd Eaton wrote “The Paleolithic Prescription: A program of diet and exercise and a design for living.” (It is hard to find these days. To find it and related titles on Amazon, look for this book first, and track the PP down via the author name Konner.)

(Added: You can probably get the The Paleolithic Prescription here.)

Richard G. Bribiescas is professor of anthropology and ecology and evolutionary biology at Yale University, where he also serves as deputy provost for faculty development and diversity. He is the author of Men: Evolutionary and Life History. He lives in Hamden, Connecticut.
Richard G. Bribiescas is professor of anthropology and ecology and evolutionary biology at Yale University, where he also serves as deputy provost for faculty development and diversity. He is the author of Men: Evolutionary and Life History. He lives in Hamden, Connecticut.
That was the first “stone age” diet book. But, it was different from all the others, and the only one worth anything. Mel and Marjorie were two of several individuals, including my advisor and theses readers, Irv Devore and John Yellen, who engaged in the famous Kalahari Project, in which the biology and lifeways of the Ju/’hoansi foragers (aka Bushmen or San) were studied intensively for several years.

The researchers noticed that there were differences in lifeways between these exemplary foragers and industrialized people’s of the West that seemed related to health and well being. They were able to link, sometimes definitively, sometimes tentatively, diet and activity levels on one hand and health on the other. Their findings, by the way, were first published in the peer reviewed literature, then turned, by the scientist themselves, into a popular book. (One of the findings eventually led to the understanding that there are different kids of cholesterol, which seem to have very different health related implications.)

My own research with the Efe (Pygmies) of the Ituri Forest, in Zaire, was an indirect offshoot of that early work. I got my PhD at the same institution, Harvard’s Anthropology Department that housed much of the Kalahari project, and the Ituri project was started by the same leader, Irv DeVore, via his students. So, the tradition of examining the lifeways of modern day foragers, in part to understand ideal human conditions, and comparing those conditions to western ways continued.

Meanwhile, one of the graduate students at Harvard, Peter Ellison (yes, he is related to that Ellison) had been interested in some work coming out of Harvard Medical school looking at hormones and behavior, especially as related to reproductive biology of human women. Building on that work, Ellison created an entirely new field of study, called “Reproductive Ecology.” He finished his PhD and was added to the faculty at the Anthropology department in one of those in between positions (as was I and many others over the years) but Peter became one of the very few such individuals to be eventually offered a tenured position with the most “always hire from outside” institutions ever. And Ellison created the Reproductive Ecology Lab within the biological anthropology wing of Harvard’s Department of Anthropology.

screen-shot-2016-10-24-at-11-01-54-amAnd, they studies the heck out of female reproductive ecology. I had the pleasure of working, almost every semester that I was there from late in my PhD cycle through my post-PhD teaching career there, to work with Mary O’Rourke (and others) who were from that lab running an undergraduate tutorial. The tutorial is three or four faculty members each running two or three groups, with about five or six students in each group. These are students majoring in Biological Anthropology, who have already taken a class or two but are on their way into the research labs. The tutorial instructors’ job is to turn these young and interested minds into the minds of proto-Anthropologists by carefully examining a different topic each week, looking at a combination of peer reviewed literature and secondary but excellent literature (back in those days, the former was easier to find).

So, I spent a lot of time hanging around with the Reproductive Ecology people (and, by the way, collecting some of their data in Zaire). Every social event had a lot of Repro Eco folks at it, so it was pretty normal for someone to pull out a box of specially prepared test tubes to get every one to provide saliva samples for some study or another. It was not long into the process of developing this subfield that the reproductive ecology of men, simpler but still important, was also taken up by this group, so everyone had an opportunity to spit into the tubes. For example:

Hypothesis: Testosterone in men varies over short time scales (of minutes, hours) during a poker game depending on which cards they are dealt, assuming the samples are not contaminated by …

… oh, never mind, you get the picture.

Anyway, it was while I was a couple of years into my own graduate career when a young man from California showed up to study anthropology, with a particular interest in Biological Anthropology. It was Richard Bribiescas. Rick and I did not hang around a lot of time, because we were both busy, but we were good friends and broke bread (a euphemism for guzzling beer but there were also tacos and cheeseburgers) quite often.

When Rick got to Harvard, there was already a strong tradition of working to understand modern human problems in the Western world by examining modern human behavior and physiology in a variety of other societies, including foragers.

Many young men and women went to the field from that department, to work in Poland, Borneo, the Amazon, the Congo. Among those, very few attempted to work in the most difficult of conditions, in a rain forest with foragers. Of those who tried most retreated and picked another topic. A few persisted and continued to study this or that thing about one of the few remaining forager group son the planet. That’s what I did, with the Efe. That’s also what Rick did, with the Ache, of South America.

And, as a result of that, Rick produced a bunch of interesting peer reviewed papers, and eventually, a book that has been out for a while now called Men: Evolutionary and Life History. A number of books had been written about female reproductive ecology, but along the way, rick became the expert on male reproductive ecology, discovering that it is not as simple as one might expect. This book is the result of that achievement.

And now, Rick is an old guy. He must be at least 45. And, as such, he has turned his attention to a new but related topic: How do men age. And, the newly produced book that comes from this research to your book shelf is How Men Age: What Evolution Reveals about Male Health and Mortality

Do not buy or borrow some book on aging written by a web site, a fake MD, or some other charlatan. Read a book on aging (in men) that first appeared many times in the peer reviewed literature, written by Harvard Trained Yale Expert Richard Bribiescas.

Note the subtitle. This is about what evolution reveals about male health and mortality. Having taught along side him many times, and after all those beers, tacos, and cheeseburgers, I can tell you that Rick knows all about evolution, and of course, he is the world’s leading expert on male reproductive ecology.

I put the Table of Contents below to give you and idea.

Rick is a great writer, and this book is fun to read.

Do the well known features of male aging have some sort of evolutonary advantage, as has been proposed for females? How much of male aging in the West is a function of our Western lifestyle, or a function of our seemingly extended lifespan? What about the contradiction between what we mere humans think of as “health” or “healthy” and what the cruel and cold process of Darwinian natural selection things about such silly things? What about sex, relationships, monogamy, polygamy, fatherhood and child rearing, in male humans in general, and across the aging process? And our brains, our obscenely large brains, what the heck are they for?

You will enjoy this book, especially if you are a man of a certain age.

Table of Contents:

Acknowledgments ix
Chapter 1 A Gray Evolutionary Lens 1
Chapter 2 Dead Man’s Curve 17
Chapter 3 Getting a Handle on Love Handles 45
Chapter 4 Older Fathers, Longer Lives 70
Chapter 5 Dear Old Dad 88
Chapter 6 Darwinian Health and Other Contradictions 106
Chapter 7 Older Men and the Future of Human Evolution 133
Notes 145
Index 169

A new study of Natural Selection in Birds

…there is a new study that has significant advantages of the Bumpus study, though the latter will still be useful in teaching about evolution because of its limitations and the questions it raises. The new study is about Cliff Swallows (Petrochelidon pyrrhonota) in southwestern Nebraska.

As you know, a lot of birds are killed in the U.S. because of collisions with vehicles. About 80 million, according to the Cliff Swallow study by Charles Brown and Mary Bomberger Brown. Brown and Brown examined the possibility that birds in a population subject to this particular form of mortality would undergo Natural Selection, with some traits that prevented death through vehicular collision being selected for over time. …

Read the whole thing here.

Among Cannibals

I have lived among Cannibals, according to a lot of people who claim to know. The number of times that the “tribal” people of the Congo have been called cannibals is too great to be counted, most notably in great literature like The Heart of Darkness but most commonly, I suspect, from the pulpit or soap box by those raising money to spread this or that word. Most Europeans and Americans don’t know it, but many people who live in the Congo are quite convinced that the bazunga … the white foreigners … are cannibals. I’ve listened closely to these assertions, made by many individuals, and I’ve lived in both places for considerable time and I can say something about these claims.

They have a case. Continue reading Among Cannibals

Darwinian Thinking From The Birds

…Louis Agassiz, the most famous scientist of his time, eclipsing Darwin in his stature and influence (up to a point) addressed this diversity across the landscape in one way. Darwin addressed it in another way. Today, most people don’t even know what Agassiz said, even though it is a perfectly rational model if you are a creationist, and something like half of all Americans are. But, his ideas would be considered absurd even by modern Young Earth Creationists (YECs). Darwin’s view, in contrast, is not absurd, but it is complicated….

Read more

The Origin of the Human Smile

i-292d5241115b67e27ce78512e86d1926-chimp_smile.jpgA 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, Daniel McNeil refers to a study that shows that while judges are as likely to convict (or not) smiling defendants, the ones who smile get lighter sentences.

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.

An Evolutionary View of Humans 5: The Opposite Sex

Efe people
Ituri Forest
Anthrophoto is an
excellent source for
anthropology stock

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