Dwarfed by the X chromosome, the Y seems more ancient than we thought (Image: Pasieka/SPL)

New research suggests that the oldest common male ancestor for all living men existed BEFORE (around 340,000 years ago) anatomically modern humans emerged around 195,000 years ago. Very interesting. This would make the oldest common male ancestor quite a bit older than Mitochondrial Eve, who is estimated to have lived approximately 190,000–200,000 years ago.

The father of all men is 340,000 years old

March 2013 by Colin Barras
Magazine issue 2908.

Albert Perry carried a secret in his DNA: a Y chromosome so distinctive that it reveals new information about the origin of our species. It shows that the last common male ancestor down the paternal line of our species is over twice as old as we thought.

One possible explanation is that hundreds of thousands of years ago, modern and archaic humans in central Africa interbred, adding to known examples of interbreeding – with Neanderthals in the Middle East, and with the enigmatic Denisovans somewhere in southeast Asia.

Perry, recently deceased, was an African-American who lived in South Carolina. A few years ago, one of his female relatives submitted a sample of his DNA to a company called Family Tree DNA for genealogical analysis.

Geneticists can use such samples to work out how we are related to one another. Hundreds of thousands of people have now had their DNA tested. The data from these tests had shown that all men gained their Y chromosome from a common male ancestor. This genetic "Adam" lived between 60,000 and 140,000 years ago.

All men except Perry, that is. When Family Tree DNA's technicians tried to place Perry on the Y-chromosome family tree, they just couldn't. His Y chromosome was like no other so far analysed.

Deeper roots

Michael Hammer, a geneticist at the University of Arizona in Tucson, heard about Perry's unusual Y chromosome and did some further testing. His team's research revealed something extraordinary: Perry did not descend from the genetic Adam. In fact, his Y chromosome was so distinct that his male lineage probably separated from all others about 338,000 years ago.

"The Y-chromosome tree is much older than we thought," says Chris Tyler-Smith at the Wellcome Trust Sanger Institute in Hinxton, UK, who was not involved in the study. He says further work will be needed to confirm exactly how much older.

"It's a cool discovery," says Jon Wilkins of the Ronin Institute in Montclair, New Jersey. "We geneticists have been looking at Y chromosomes about as long as we've been looking at anything. Changing where the root of the Y-chromosome tree is at this point is extremely surprising."

Digging deeper, Hammer's team examined an African database of nearly 6000 Y chromosomes and found similarities between Perry's and those in samples taken from 11 men, all living in one village in Cameroon. This may indicate where in Africa Perry's ancestors hailed from.

Older than humanity

The first anatomically modern human fossils date back only 195,000 years, so Perry's Y chromosome lineage split from the rest of humanity long before our species appeared.

What are the implications? One possibility is that Perry's Y chromosome may have been inherited from an archaic human population that has since gone extinct. If that's the case, then some time within the last 195,000 years, anatomically modern humans interbred with an ancient African human.

There is some supporting evidence for this scenario. In 2011, researchers examined human fossils from a Nigerian site called Iwo Eleru. The fossils showed a strange mix of ancient and modern features, which also suggested interbreeding between modern and archaic humans. "The Cameroon village with an unusual genetic signature is right on the border with Nigeria, and Iwo Eleru is not too far away," says Hammer.

Chris Stringer at the Natural History Museum, London, was involved in the Iwo Eleru analysis, and says the new Y chromosome result highlights the need for more genetic data from modern-day sub-Saharan Africans. "The oldest known fossil humans in both West Africa at Iwo Eleru and Central Africa at Ishango [in Democratic Republic of the Congo] show unexpectedly archaic features, so it certainly looks like we have a more complex scenario for the evolution of modern humans in Africa."

Journal reference: American Journal of Human Genetics, doi.org/kp4

Lynn E. O'Connor - Male Dominance and Female Depression: Based on Ideas?

Lynn E. O’Connor, Ph.D. in her Psychology Today blog, Our Empathic Nature, published this interesting look at how our primate relatives might provide insight into our own social construction of gender stereotypes. The research seems to indicate that depression levels in females, both chimps and humans, is relatively identical to that of males, until puberty. Once puberty arrives, the males become more physically dominant and the females become much more likely to experience depression. Food for thought.

Male Dominance and Female Depression: Based on Ideas?

An explanation for cultural differences in orangutans might have relevance

Published on December 31, 2012 by Lynn E. O’Connor, Ph.D. in Our Empathic Nature

Chimpanzee's Emotions Similar to Ours

Over a decade ago I conducted a study with James King and Jack Berry on antecedents to psychopathology in chimpanzees. We used data that King had first collected in a study of personality in Chimps in 12 zoos, maintained under the auspices of the Jane Goodall Institute. Meaning the Chimps were living in as benign circumstances as zoos can provide, with efforts made to provide an interesting environment given the confines. The method used was to have zookeepers and volunteers who knew the Chimps well sit and observe them for hours and hours, and mark down how much they exhibited a variety of behaviors, derived from 43 specific personality attributes (used previously with people). This included behaviors like aggressiveness, friendliness, sociability, intelligence, and other obvious characteristics. King and his colleague Figueredo found the Chimps could be categorized on a scale very close to the most commonly used “Big Five Factor” personality scale used with people. There was one additional factor related to “Dominance” although I questioned its inclusion, as the attributes that went into it were also frequently found in “Extraversion,” one of the “big five factors.”

I began this new study by speaking at length to the zookeepers who had been part of the original study. Some of them had been with their “group” of Chimps for 15 years or longer. They really knew and spoke about their Chimps much as we speak of our children and family members. I heard stories, detailed fantastic stories of the Chimps behaviors. Some sounded quite screwy, along the lines of what, if it had been a person, we would have diagnosed her (yes it’s usually a “her”) as suffering from a “borderline personality disorder.” Others would –had they been people—been called “schizoid (personality disorder)” or “antisocial personality disorder” (we all know some of them, they take what they want, push to the front of the line, and don’t seem to worry whose feelings they hurt in the process). Others seemed to be quite normal, just ordinary, getting along with other Chimps kinds of behavior. After transcribing all of these extensive interviews, I read them over and over. Things just popped out at me, and I went to what was then our “diagnostic bible” the first version of the “DSM-IV” that psychiatrists and psychologists use to diagnose people with mental disorders. I started looking through disorders, characterized by “criteria” otherwise known as specific symptoms. I was limited to behavioral symptoms since I didn’t know what was in the Chimps’ minds, only how they behaved. My colleague Jack Berry joined me on this. Together we came up with five scales that were made up of “criteria” as laid out by the DSM-IV, and considered them antecedents to psychological problems we see in people. A few were the most commonly known psychological problems, like “depression” and “anxiety.” The others were “personality disorders (PD)” and specifically, “borderline PD”, “antisocial PD,” and “schizoid PD.” We then found the attributes from the original personality scales that fit into the characteristics or criteria for these disorders, thereby coming up with “antecedents to psychopathology in chimpanzee scales.”

What happened when we ran the statistics was amazing. Chimps I had thought were “schizoid” actually came out “schizoid” on our scales. One really mean girl, “Lila” sure enough showed up as “antisocial PD” on our scales. But most astounding was that we found that before adolescence, males and females were identical in proneness to depression. Sometime during adolescent however, the females zoomed ahead and became significantly more depressed than the males. What was so striking here was that they followed the exact pattern we have repeatedly found in people.

Our question then was –why did this happen (in Chimps or in our species)? Perhaps it was due to hormones and rising estrogen? Or was it because females were not as quick at metabolizing serotonin which left them more vulnerable. Biological considerations aside we wondered about the role of social environment – In other words - Is male dominance in any way related to the observed differences in proneness to depression between males and females. We wanted to look at Pygmy Chimps, better known as Bonobos. They’re the species that “makes love not war.” When they come upon a tree with ripe fruit, the first thing they do before jumping in – they all make love to one another. Males and females, males and males, females and females, they have a sex orgy. Then, apparently having reduced potentially competitive tension, they all enjoy the fruit together. Furthermore bonobos share often (so do chimps in their natural habitat, but not quite as much as Bonobos). Most striking -- in Bonobos culture, females are dominant because they stick closely together. If a male aggresses upon a female, the females gang up and go after the guy who flees as fast as he can. While there is infanticide among Chimps, there is no such thing with Bonobos. The women really stick together and thus their young are well protected, as well as one another. For all these years since we did this study, I’ve had this question – if we studied Bonobos in zoos, replicating the way we studied the Chimpanzees, would we find the females getting significantly more depressed than the males, around adolescence? Or would the female dominance protect them. Maybe the males would get more depressed. Is it social environment that leads to depression? We have no way to know. Frans de Waal, a world expert on Bonobos, told me he thought we’d be unable to find enough Bonobos to replicate the study, even if we looked at zoos world wide.

Orangutan culture transmitted by ideas

Then a few weeks ago I read a piece by Jason Goldman, a Scientific American blogger. He is summarizing research that demonstrates that Orangutan’s culture (which differs from group to group) is being passed on by ideas instead of by genetic differences, or some other physical or concrete environmental explanation.

In Orangutans, just seeing a behavior before a child has the physical skills to actually do it, allows them to do it quite easily when they are old enough to develop the skills. But Orangs from a group where the behavior was never done so the children never saw it, have a much harder time learning it, when exposed to the behavior under different conditions, in a shelter where Orangutans from differing cultures are mixed together. Maybe the same is true of male or female dominance, and subsequently, maybe the onset of female depression in adolescence is part of a cultural package, made up of ideas carried from generation to generation. Could this possibly hold an answer to the mystery of the onset of adolescent depression in Chimpanzees and in our own species. Could the cultural habit of male dominance be something the young have to see, long before they can actually do it. Could the cultural habit of females sticking together and chasing off males who grew offensive, thereby establishing a female dominant culture be something youngsters just have to see, in order to later imitate the same pattern? I don’t have the answer but Goldman’s summary of this new research really made me wonder if male dominance is based on cultural ideas and cognitions and thereby possibly subject to change, albeit with effort.

Male dominance at work, still very present

The story of our Chimpanzee research is sadly an example of how the idea of male dominance holds power in our culture. Our study was presented at the APA in 2001, over a decade ago. Then a young alpha male joined King’s group. I’m not naming names. He grabbed the data, began to dominate the show, claimed he added some Chimps to the data, re-analyzed it and came up with the same results. But when I tried to publish our findings, he refused to give me the original data, or the data set to which he’d added. Feeling uneasy at publishing something based on a data set I was unable to review myself, presenting findings while being unable to re-analyze data on my own --well that seemed potentially unethical. Why would I be denied the data set, having been the principal investigator on the study? Must be the pervasive idea of male dominance. I withdrew the piece from the Journal to which I’d sent it. The new alpha male who had nothing to do with the original study is now getting a bigger and bigger name in animal and human personality. I accept it (almost), we live in a culture that’s still unfortunately male dominated at least in science. But I found Goldman’s review of the orangutan research a comfort. If social differences or culturally specific skills are related to cultural ideas, this thing we know as male dominance may all change in the future. Ideas may be far more malleable than something wired into our genetic material.

References

Gruber T., Singleton I. & van Schaik C. (2012). Sumatran Orangutans Differ in Their Cultural Knowledge but Not in Their Cognitive Abilities, Current Biology, 22 (23) 2231-2235. DOI: 10.1016/j.cub.2012.09.041

King JE, Figueredo AJ. (1997). The Five-Factor Model plus Dominance in chimpanzee personality. J Res Pers 31:257–271.

O'Connor, L. E., Berry, J. W., King, J., Landau, V., & Pedersen, A., (2001). Chimpanzee subjective well-being and psychopathology. Presented at American Psychological Association, August, 2001, San Francisco California.

De Waal, F. & Lanting, F. (1998). Bonobo: The forgotten Ape. Berkeley: U. California Press.

Dogs Decoded - The Remarkable Bond Between Humans and Their Dogs

Man's best friend. . . . In country music and popular cliche, nothing comes between a man and his dog, not even (or especially) his woman. This 2010 NOVA episode, reposted at Documentary Heaven, looks at the long and complicated history between human and dogs.

Dogs Decoded

Broadcast (2010) "Dogs Decoded" reveals the science behind the remarkable bond between humans and their dogs and investigates new discoveries in genetics that are illuminating the origin of dogs—with surprising implications for the evolution of human culture. Other research is proving what dog lovers have suspected all along: Dogs have an uncanny ability to read and respond to human emotions. Humans, in turn, respond to dogs with the same hormone responsible for bonding mothers to their babies. How did this incredible relationship between humans and dogs come to be? And how can dogs, so closely related to fearsome wild wolves, behave so differently?

Dogs have been domesticated for longer than any other animal on the planet, and humans have developed a unique relationship with these furry friends. We treat our pets like a part of the family, and feel that they can understand us in a way other animals can't. Now, new research is revealing what dog lovers have suspected all along: Dogs have an uncanny ability to read and respond to human emotions. Humans, in turn, respond to dogs with the same hormone responsible for bonding mothers to their babies. How did this incredible relationship between humans and dogs come to be? And how can dogs, so closely related to fearsome wild wolves, behave so differently? It's all in the genes.

Dogs Decoded investigates new discoveries in genetics that are illuminating the origin of dog - with big implications for the evolution of human culture as well. In Siberia, the mystery of dogs' domestication is being repeated--in foxes. A fifty-year-old breeding program is creating an entirely new kind of creature, a tame fox with some surprising similarities to Man's Best Friend.

NPR - How Dogs Evolved Into 'Our Best Friends'

 

Gray Wolves

One of the great cliches of movies and country music is a man and his dog. For a lot of us, our dogs are family - and the only "friend" in our lives who always accepts us exactly as we are, no matter what stupid thing we have done.

Naturalist Mark Derr has written How the Dog Became the Dog — From Wolves to Our Best Friends, a book that looks into our history with the best friend some of us have ever had.

For a little extra background, Archaeology ran an article a year or so ago on the history of domesticated dogs from the perspective of their field.

How Dogs Evolved Into 'Our Best Friends'

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Dogs today evolved from wolves who first developed a relationship with humans on the hunting trail.

November 8, 2011

Dogs have aided humans for thousands of years. Man's best friend has provided protection, companionship and hunting assistance since the days of the earliest human settlements.

But how and when dogs evolved from wolves is a matter of debate. Naturalist Mark Derr says there are two main schools of thought: Some researchers believe that humans domesticated wolves who were scrounging around their villages for trash. Others think that humans were taking care of wolves from the time they were puppies — until enough puppies were tamed and they somehow then evolved into dogs.

"Neither explanation seems satisfactory," writes Derr in How the Dog Became the Dog — From Wolves to Our Best Friends. "That is why there's no consensus."

In his book, Derr explores how the relationship between humans and wolves developed, and how that relationship then influenced the physical evolution of wolves into dogs. He tells Fresh Air's Dave Davies that he believes humans and wolves developed a close relationship after recognizing themselves in each other while hunting on the trail of big game.

How the Dog Became the Dog: From Wolves to Our Best Friends

by Mark Derr

Hardcover, 287 pages

MORE ON THIS BOOK:

NPR reviews, interviews and more

"[That's when] they started traveling together, and they've been at it ever since," he says. "The dog is a creation of wolves and humans — of two equal beings that came together at a certain point in history and have been together ever since."

Derr says our ancestors likely followed behind wolves as they hunted for game on the trail. Wolves, in turn, learned to wait for scraps from bipedal hunters — who were far more accurate with their rudimentary weapons than the wolves were with their teeth.

"The wolf could say, 'These people are far more profligate hunters than we are. When they go out, they always leave a surplus. It's easier for us to take the scraps that they have than to hunt,'" says Derr. "Hunting is a highly energetic activity. And they could learn from each other, just by observing each other."

As humans and wolves began to work and live together, physical features on the wolf began to change: Its skeletal frame grew smaller, and its jaw shortened. Wolves that socialized well with humans began to travel with them, and then were able to pass on their genes.

"You had populations of dog-wolves that became isolated, and in doing so, they began to inbreed," says Derr. "And when you inbreed, you get genetic peculiarities that arise, and then those peculiarities become part of the population. If they work or become popular or have some function of beauty or utility, then they were kept by the humans — and that population then spreads those through other populations through breeding."

Fossils of wolves and dogs have been found in early hunting camps. In China, researchers have found evidence that some hunters were raising millet to feed to their hunting companions.

"This kept the dogs alive during times of thin meat," says Derr. "When they weren't getting as much meat as they wanted, they would feed [the dogs] millet. That would indicate that the early dog was being used as a hunter, but also that it was highly valued."

Interview Highlights

On puppies

"There's something about them that makes us friends with them. There are people who dislike dogs for sure. But dogs also have an uncanny ability ... to walk in a room and pick out the one or two who seem to dislike dogs the most and make friends with them. It's happened to me with some of my dogs on numerous occasions. I think there's a deep — some people call it love, I call it a 'deep empathy' between these two species that resonates with each other in a way that makes them comprehensible to each other, even though they don't speak the same language."

On small dogs

"There are some people who suggest that the small dog, because of its size, was a curiosity, an easier dog to have as a companion. In much of American history and even today, you'll find people who have two dogs: a large dog, who is in the yard, and a small dog, whose job is to kill rats and make a noise if somebody comes near, be a companion or playmate for the children, or a guardian."

On the cultural evolution of dogs

"This is one of the reasons why people like to speak of the dog as a separate species than the wolf, even though they're so closely related. The dog lives with us in a way that wolves don't. It is created by us in different ways."

On breeding

"I'll say it bluntly, and it has to be said: Some of these breeds are incapable of giving birth without C-section. ... I think that it certainly is wrong to produce animals that aren't healthy. It's bad for the animal and bad for the people who take them into their homes and find out that this dog they love is going to die at a very young age because of an inheritable disease. ... We really should ask ourselves whether it is fair to the animal to do that. I am of the opinion that it's not."