Category Archives: Evolutionary Biology

Darwin Quotes, Assembled

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From Janet Browne, the author of Charles Darwin: A Biography, Vol. 1 – Voyaging and other works about Charles Dawin, The Quotable Darwin.

Quotes by Charles Darwin are not just the stuff of memes. Even the fake quotes. They can be the center of long arguments, or at least, they can significantly augment the arguments. For example, did you know that while Darwin never used the term “missing link” he did talk about missing links quite a bit, missing links are central to his thinking about evolution, and all those writers of today who claim that we must never speak of missing links are misguided? Continue reading Darwin Quotes, Assembled


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Gene Therapy Is Starting To Be A Real Thing

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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


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How long is a human generation?

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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 Cultural Generation but that should really be called a Societal Generation, and then there is the Designated Generation and finally, the Historical-Long Generation. You will find some of these terms identified on genealogical web sites, Teh Wiki and elsewhere, and some of them are introduced here. (References provided below.)

More broadly speaking, humans have identifiable meaningful generation-related terminology and cultural concepts in many but not all societies, and when it does occur, it is more common to find the concept in age-graded societies or societies in which marriage arrangements are fairly strictly enforced (or at least strongly hoped for) by the ascending generation.

A Biological Generation


…is simply the unscaled transition from one parent to one offspring. In humans, the Biological generation does not have a standard length but there are limits. So you are in one generation, your mother the previous, your child the next one after you, etc. regardless of when any of you were born. As long as your Uncle Willard does not marry your Sister Betty Jean, this is not complicated; This is what people often mean when they use the term “generation” but not what they mean when they ask the question “how long is a generation.”

A Dynamic Generation


…is a concept used by anthropologists but not usually with this term. This is similar to the biological generation but applied more broadly across a group of people. You (Ego) relate to everyone else of your age as being in your generation (your siblings, your parents siblings children, etc.). The first ascending generation (your parents and those in their generation), the second ascending generation (grandparents and their generation) etc. go one way in generational time. Going the other way, your children and their generation are the first descending generation. Your grandchildren and their cohort members are the second descending generation. Etc.

Those methods of reckoning generations have to do with the relationship between people. Another reason to reckon generations is either to do demographic (or economic) analysis or to test and analyze genealogies. For this you want to know how long a dynamic generation (or a biological one) usually is. For instance, a genealogist wants to know this: From the point of view of some long-dead relative, is the time span between the birth date of a grandparent and the birth date of a great grand child … thus, the span of time of four complete generations … reasonable? If such a span is 200 years, that means that an average of 50 years time passed from birth of a person to that person giving birth to the person in line. Implausible. If the total span is 40 years, that means ten year olds were having babies (on average). Also implausible. Either way, some part of the hypothetical genealogy is messed up and it’s back to the church records, vital statistics, and Mormon database for you. This is a Familial Generation.

In the “old days” (whenever that was) people often used the value 20 to represent Familial Generations. So, a person born on the first day of a century may well have had a great great great grandparent born around the beginning of the previous century. Today, with lager age at first birth for women being the rule, we tend to see 25 years as the recommended estimate for Familial Generations.

A Cultural or Societal Generation


…is a cohort (a bunch of people born during a specified range of time) with a name that has some sort of meaning to those who use it. The following are widely recognized, given here with the midpoint of the generally accepted range of birth dates:

  • Lost 1914
  • Greatest 1923
  • Silent 1935
  • Baby Boom (Boomers) 1955
  • Generation X 1968
  • Generation Y 1975
  • Generation Z or I 1992

(See comments below for people fighting about these names and dates. I accept Teh Wiki as the final word on this, so I take this list as perfectly accurate and complete.)

Several things are noticed in this list. The first three relate to major historical events (World Wars, the Great Depression) while the later ones are vague, stupid, and obviously little more than lame attempts by people who wish they were part of a generation to name themselves. This leads to the X and Y generations to be floating in broader time ranges (see Teh Wiki) and very arguable. The Z generation is clearly an afterthought. I assume everyone was so focused on the Millennium that they forget to be in a generation for a decade or so, and then had to catch up.

Some of the more primitively sexy and exotic tribal cultures of the world of the world have a strict age grading system. This is where individuals are in a specific age-defined stratum, and there are several strata. Often there are different age-grades for males and females, and often there are more age-grades for males than females. Individuals of a particular age grade always X and never Y (fill in cultural prescriptions for X and cultural proscriptions for Y). The Pokot of East Africa are one example. These age grades can be termed Designated Generations and include not only groups like the Pokot but also Americans who have very strongly age-graded designations.


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Among the Pokot males of a certain age wear a certain hairdo. Males of a certain generation get married. All the important things you can do or not do are defined by one’s age grade. As young men age they want to move to the next age grade, and often take serious risks to do so. In one Pokot group, the boys of one age grade would typically wear the hairdos of the Ascending Generation. Males in the Ascending Generation would then beat the crap out of them. When the beatings became too common and severe (sometimes deadly) the Ascending Generation of the Ascending Generation (the “Elders”) would declare that it is time for everyone to move up one generation, and a ceremony would be held.

In that particular group the ceremony applied to many different villages, and representatives from each village had to bring to the major chief’s village one head of cattle. The cattle were all slaughtered and the fresh meat laid out on racks to be guarded from lions and hyenas overnight by the chief, alone. If any of the meat was taken by predators, the chief was fired and a new chief appointed, everyone was sent home and were required to return with a fresh head of cattle, and the ceremony was re-started with the new chief. But I digress.

The Historical-Long Generation is my own invention. This is the period of time that is just short enough for a person to have a conversation with another person about shared memories where those memories are separated in time by the maximum amount possible for our species. Let me explain further:

Just today, the last surviving US veteran of World War I died. When I was a kid, I went to (or marched in) parades in which there were lots of veterans. Most vets in the parade were of World War II. Korea was not ever represented. The Viet Nam Vets were busy in Viet Nam being Viet Nam soldiers, so they were not in the parades. But World War I was represented by the grandpas and there were a lot of them.

And, leading all of the veterans in the parade was this one guy who looked quite dead, eyes closed, not apparently breathing, wearing a 19th century Slouch Hat and covered with a blanket and slumped in wheel chair pushed by members of the VFW Ladies’ Auxiliary, and he was the only remaining veteran in town of the Spanish-American War. I know he was not in fact dead because he was in the parade several years in a row. That war was in 1898, and the parades I remember must have been from the mid 1960s. I assume he was a drummer boy, perhaps 10 or 11 at the time of the war. The last surviving vets from Civil War were similar: Boys who served in the military as aides or drummers. The point is, one could argue that a historical-long generation is about a century, because that old guy and I share involvement in an event … marching in those parades … that link two memories, the parade and the war, which were about 100 years apart.

I have an even better memory. The Emancipation Proclamation was signed on Januray 1st, 1863. When that happened, a toddler who’s last name was Alexander and who was born as a slave in the Carolina’s became free. Later, his family moved to Albany, New York. In around 1968 or 1969, my father asked me to accompany our congressman, Representative Samuel A. Stratton (famous for introducing the bill to give us Monday Holidays, I am told) to an old tenement building in “Teh Ghetto” and bring him up to the third floor to meet Mr. Alexander, the now old former infant slave. I did so, and we all chatted for a while. I was about ten, and Mr. Alexander was closer to 110. He had memories of the assassination of Abraham Lincoln that were similar to my memories of the assassination of John F. Kennedy: Vague, mostly about the aftermath and not the event so much, but seemingly real. We shared memories that were a century apart in time, and in this case, interestingly parallel.

So, the Historical-Long generation is a century. If you meet me and shake my hand, you are shaking a hand that has shaken the hand of a man who was an American slave. Meaningless, yet profound.

Fox, Robin.Kinship and Marriage: An Anthropological Perspective (Cambridge Studies in Social and Cultural Anthropology)

Lutz, Catherine. Reading National Geographic

Teh Wiki. Generation.

Teh Wiki List of generations.


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Aging in men: An evolutionary perspective

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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


In homage to an inspiration of this post, I provide this link to the secret, generally unseen obituary of Professor Irven Boyd DeVore.



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Is Human Behavior Genetic Or Learned?

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Imagine that there is a trait observed among people that seems to occur more frequently in some families and not others. One might suspect that the trait is inherited genetically. Imagine researchers looking for the genetic underpinning of this trait and at first, not finding it. What might you conclude? It could be reasonable to conclude that the genetic underpinning of the trait is elusive, perhaps complicated with multiple genes, or that there is a non-genetic component, also not yet identified, that makes finding the genetic component harder. Eventually, you might assume, the gene will be found. Continue reading Is Human Behavior Genetic Or Learned?


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A new study of Natural Selection in Birds

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…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.


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Critique of Rebecca Watson's Talk: Haters gonna hate.

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Whinging About Skepchick

A critique of a talk by Rebecca Watson is very likely heavily influenced by the critiquer’s membership in one group or another as defined by The Great Sorting. This not because Rebecca is a polarizing person. It is because she has been outspoken on issues that tend to polarize people, like feminism. This polarization is enhanced by the fact that a break-off group of skeptics have chosen to join the haters rather than the thinkers and doers. Also, she leads a group of women who have tried to open up the Skeptical Community to having more female participants and to more frequently address women’s issues, and this has led to significant push back. As you listen to Rebecca’s recent talk on Evolutionary Psychology or read critiques of it, especially those that specifically call her talk “science denialism” or “creationism” or some other absurd thing, keep that in mind. Continue reading Critique of Rebecca Watson's Talk: Haters gonna hate.


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Among Cannibals

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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


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Darwinian Thinking From The Birds

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…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


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The Origin of the Human Smile

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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:
i-dd043713df73be0b845ef877e5482e6e-smiling.jpg

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:
i-01d0bd42a7c6b68e9fcef589615dafcc-notsmiling.jpg

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:
i-6d64822ef22db7742c26efe2380c9bf1-cat_eat_you.jpg

As for lunch, Wednesdays are good for me.


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