The Primate Diaries

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Notes on science, politics, and history from a primate in the human zoo.

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  • November 9, 2009
  • 12:30 PM
  • 2,195 views

Reciprocity and the Anthropology of Organ Transplants

by Eric Michael Johnson in The Primate Diaries

Reciprocity is an intrinsic feature of human beings as well as most species of ape. Chimpanzees and bonobos regularly engage in granting gifts of food and expect a return on their generosity (those who don't reciprocate are less likely to receive such gifts in the future) (de Waal and Brosnan 2006). This "tit-for-tat" basis of exchange exists in all human societies and becomes ritualized based on the cultural norms that are present. One of the most well known descriptions of reciprocity among........ Read more »

Margaret Lock. (2002) Twice Dead: Organ Transplants and the Reinvention of Death. California Series in Public Anthropology, no. 1. . info:/

  • November 5, 2009
  • 06:15 PM
  • 1,706 views

Remember, Remember the Fifth of November

by Eric Michael Johnson in The Primate Diaries

Remember, remember the fifth of November,
The gunpowder treason and plot,
I know of no reason
Why the gunpowder treason
Should ever be forgot.

On this day, in 1604, Guy Fawkes was arrested in his attempt to overthrow the English monarchy by blowing up the House of Lords and assassinate King James I (who would have been present at the time). Since his arrest Fawkes' crime has been condemned as terrorism motivated by fanatical Catholic outrage against the Protestant regime of James I. However, ........ Read more »

  • October 28, 2009
  • 06:00 PM
  • 2,137 views

Eye of the Beholder

by Eric Michael Johnson in The Primate Diaries

As a species we are consumed by love. Ask yourself, how many cultural productions (films, stories, songs, dances, arts) do not have love, the loss of love or the absence of love as their central theme? Would you be satisfied with what was left over? That fact that love has so much power over us is just one reason why evolutionary research is so fascinating.

A well-worn trope of human culture is mens obsession with female infidelity. Othello. Madame Bovary. Desperate Housewives. These are........ Read more »

  • October 26, 2009
  • 06:25 PM
  • 1,929 views

Republican Losers Have Lower Testosterone

by Eric Michael Johnson in The Primate Diaries

In a new understanding of the term power grab, researchers have shown that the supporters of a political candidate literally have their power taken from them after they lose an election. In a new study by Steven J. Stanton and colleagues in the open-access journal PLoS ONE, researchers asked 163 Republican and Democratic voters (57 of whom were men) to provide saliva samples both before and after the 2008 election between John McCain and Barack Obama. What the researchers determined was that R........ Read more »

  • October 22, 2009
  • 12:10 AM
  • 2,032 views

Male Chauvinist Chimps or the Meat Market of Public Opinion?

by Eric Michael Johnson in The Primate Diaries

Female chimpanzee with her infant requests meat after a successful hunt.
Image: David Bygott / Tree of Life Web Project

Owen Lovejoy's recent paper about Ardipithecus ramidus and human origins (see my detailed critique here) bases its argument on the male provisioning observed in chimpanzees. However, what went unacknowledged in his theory was the inherent gender bias it represented. A perfect example of this was observed in April with the release of the very study on provisioning behavior th........ Read more »

  • October 19, 2009
  • 09:49 AM
  • 1,883 views

Reexamining Ardipithecus ramidus in Light of Human Origins

by Eric Michael Johnson in The Primate Diaries

Grand evolutionary dramas about human origins capture our imagination and the stories provide context as to how we view ourselves. They are the scientific version of creation myths. However, unlike Adam and Eve being fashioned in the garden or humanity being vomited up by the giant Mbombo (as the Bakuba people of Congo believed), scientific origin stories are rigorously critiqued based on the best available evidence.

Friedrich Engels, a sociologist and future collaborator with Karl Marx, wrot........ Read more »

  • October 16, 2009
  • 04:05 PM
  • 1,826 views

The Potent Fear of Male Menopause

by Eric Michael Johnson in The Primate Diaries

Three products that profit on male insecurities (Enzyte, Viagra and Tiger Penis Wine)
Note: the third image is from a campaign to encourage people to stop, not an actual ad.


In my earlier posts I explored why women experience menopause and discussed the Grandmother Hypothesis as a leading explanation. There is accumulating evidence that suggests reproductive senescence in women is an adaptation promoting inclusive fitness. However, there are many claims that menopause also occurs in men. Th........ Read more »

  • October 15, 2009
  • 10:33 AM
  • 1,835 views

Science Got Ardi Wrong or: The Enigma of Ardipithecus

by Eric Michael Johnson in The Primate Diaries

There may need to be a significant revision in the recent description of one of humanity's oldest ancestors. Ardipithecus ramidus (or "Ardi" for short), the 4.4 million year old hominid fossil discovery, has been a godsend to paleoanthropologists (pun intended). But one of the key researchers has made what could be a serious error in his interpretation.

Christopher Ryan, who writes for Psychology Today at his blog Sex at Dawn (also the title of his forthcoming book) has discovered evidence th........ Read more »

  • October 14, 2009
  • 02:20 AM
  • 1,752 views

Reply to Moran: The Grandmother Hypothesis of Menopause

by Eric Michael Johnson in The Primate Diaries

In my earlier post I discussed the "Grandmother Hypothesis" as an explanation for human reproductive senescence, or menopause. A problem arises in understanding why women forgo one-third (and sometimes as much as one-half) of their reproductive lives, a condition unique in the natural world. Could this just be a neutral mutation, an artifact of longer human lives, or might it be a product of natural selection? If the latter, what selection pressure(s) could result in this unique human adaptat........ Read more »

Shanley, D., Sear, R., Mace, R., & Kirkwood, T. (2007) Testing evolutionary theories of menopause. Proceedings of the Royal Society B: Biological Sciences, 274(1628), 2943-2949. DOI: 10.1098/rspb.2007.1028  

  • October 12, 2009
  • 04:24 PM
  • 2,074 views

Why Do Women Experience Menopause?

by Eric Michael Johnson in The Primate Diaries

Whether they're referred to as hot flashes, power surges or personal summers, the experience of menopause is not fun. But could it be the result of human evolution?

One of the most fascinating areas of research in evolutionary studies is the question of reproductive senescence. Why do women go through menopause? Chimpanzees and bonobos, our closest evolutionary relatives who we share 99% of our DNA with, are reproductive throughout their lifespans but human women can spend the last third of th........ Read more »

Lahdenperä, M., Lummaa, V., Helle, S., Tremblay, M., & Russell, A. (2004) Fitness benefits of prolonged post-reproductive lifespan in women. Nature, 428(6979), 178-181. DOI: 10.1038/nature02367  

  • October 11, 2009
  • 07:00 AM
  • 1,997 views

Does Taking Birth Control Alter Women's Sexual Choices?

by Eric Michael Johnson in The Primate Diaries

In the classic film Casablanca, the drama hinges on Ilsa's choice between two men: her kind and supportive husband or her rugged and passionate ex-lover. In a moment of abandon, Ilsa returns to her lover's arms only to later change her mind and choose the more stable life she would have with her long-term partner. But what if something as simple as a pill had caused Ilsa to feel differently and make the opposite choice?

In a new paper in the journal Trends in Ecology and Evolution biologists ........ Read more »

  • September 21, 2009
  • 02:00 PM
  • 2,529 views

The Sacrifice of Admetus: How the Evolution of Altruism Reveals our Noblest Qualities

by Eric Michael Johnson in The Primate Diaries

Heracles battles Death for generosity's sake / Frederic Lord Leighton (1869-71)

Whereas great scientific theories stand the test of time when they accurately predict the natural world through repeated empirical trials, great literature transcends the ages when it speaks to universal qualities of human experience. Such inspirational works can also, without the authors realizing at the time, reveal the sublime beauty and tragedy of our evolutionary drama. Few classical authors have tapped into ........ Read more »

Felix Warneken, Brian Hare, Alicia P. Melis, Daniel Hanus, & Michael Tomasello. (2007) Spontaneous Altruism by Chimpanzees and Young Children. PLoS Biology, 5(7). DOI: 10.1371/journal.pbio.0050184  

Claudia Rutte, & Michael Taborsky. (2007) Generalized Reciprocity in Rats. PLoS Biology, 5(7). DOI: 10.1371/journal.pbio.0050196  

  • September 7, 2009
  • 08:50 PM
  • 1,716 views

Unicolonial Ants Pose Challenge to "Selfish Gene" Theory

by Eric Michael Johnson in The Primate Diaries

Unicolonial ants, such as these Argentine ants (Linepithema humile), are genetically unrelated but will cooperate to defeat a much larger adversary.
Source: Alex Wild / Live Science

It has been a mainstay of evolutionary theory since the 1970s. Natural selection acts purely on the level of the individual and any cooperation observed between organisms merely hides a selfish genetic motive. There have been two pioneering theories to explain cooperation in the natural world given this framework:........ Read more »

Helantera, H., Strassman, J.E., Carrillo, J., Queller, D.C. (2009) Unicolonial ants: where do they come from, what are they and where are they going? . Trends in Ecology and Evolution.

  • August 17, 2009
  • 12:00 PM
  • 2,668 views

Those Cheating Testicles, or Who's Your Baby?

by Eric Michael Johnson in The Primate Diaries

Benjamin Franklin once quipped, "Where there's marriage without love there will be love without marriage." His affairs are well known in American history, however this founding father may have been stating a truth extending to evolutionary history as well.

Christopher Ryan (author of the forthcoming Sex at Dawn) offers some thoughts on the role of novelty in the sex lives of our favorite primate. He suggests that men are drawn to variety in sexual partners while women are drawn to variety in ........ Read more »

  • August 7, 2009
  • 06:05 PM
  • 2,132 views

Why Chimpanzees Make Bad Suicide Bombers

by Eric Michael Johnson in The Primate Diaries

The Evolution of Spite is the Evil Twin of Altruism



Someone walks into a crowded restaurant, looks about the diners calmly, and blows themselves up as well as everyone nearby. Why? This is a scenario that forces us to explain the dark side of human nature. Why do humans have a capacity for such hate that they'll take their own lives in order to destroy others?

A study in Proceedings of the National Academy of Sciences on chimpanzee behavior suggests that humans may be alone in this way: a........ Read more »

Jensen, K., Call, J., & Tomasello, M. (2007) Chimpanzees are vengeful but not spiteful. Proceedings of the National Academy of Sciences, 104(32), 13046-13050. DOI: 10.1073/pnas.0705555104  

  • July 17, 2009
  • 02:53 PM
  • 2,163 views

Adoption in Non-Human Primates

by Eric Michael Johnson in The Primate Diaries

How genes for altruism can benefit strangers as well as kin

The generosity of adoption has long been considered a unique human hallmark.

Image: Shadows of Forgotten AncestorsFor decades it was conventional dogma that humans were the only species that used tools. "Man the Toolmaker" was our celebrated designation. The hominin fossil Homo habilis (or "handy" man) was even defined within our genera primarily because the skeleton was associated with stone implements. However, when Jane Goodall ........ Read more »

  • July 14, 2009
  • 11:05 PM
  • 2,113 views

Darwin's Connection to Nazi Eugenics Exposed

by Eric Michael Johnson in The Primate Diaries

On this day 76 years ago (July 14, 1933) a sterilization law was passed in Nazi Germany, known as Gesetz zur Verhütung erbkranken Nachwuchses (Law for the Prevention of Genetically Diseased Offspring). Any German was a target if they were found to be suffering from a range of perceived hereditary ailments, such as congenital mental deficiency, schizophrenia, manic-depressive insanity, epilepsy, Huntington's chorea, blindness, deafness, any severe hereditary deformity or even severe alcoholism......... Read more »

  • July 8, 2009
  • 04:50 PM
  • 2,350 views

Brooding Angelmakers

by Eric Michael Johnson in The Primate Diaries

Offspring Abandonment in the Ancient and Natural World



In the Greek tragedy Oedipus Rex the great kingdom of Thebes is condemned following a case of mistaken identity (and a little patricide). The sordid tale begins when the infant prince is abandoned by his parents (see right) after learning of a prophecy that his son will one day murder his father, marry his mother and assume the throne. His ankles pierced with a spike, young Oedipus is sent to be abandoned atop mount Cithaeron. Whi........ Read more »

  • July 7, 2009
  • 04:01 AM
  • 2,230 views

The Struggle for Coexistence

by Eric Michael Johnson in The Primate Diaries

A cancer cell may eventually kill its host when an error in transcription causes it to multiply despite the signals not to from its external environment. Likewise, evolutionary theory has long assumed, following the work of Thomas Malthus, that all species attempt to maximize their reproductive success and grow their range exponentially. This overpopulation results in a "struggle for existence" over the remaining resources and, if gone unchecked, may result in a massive plunge in popul........ Read more »

  • June 20, 2009
  • 10:21 PM
  • 1,206 views

Repost: The Biology of a Mother’s Love

by Eric Michael Johnson in The Primate Diaries

Mother-infant bonds predicted by hormone levels in humans and other mammals

Image: Statue in Zamora, Spain / heidi.vilppola

My son is expected to be born any day now and it has been a fascinating experience watching my partner’s changes during these past nine months. I’ve been reading a great deal about evolutionary perspectives on birth and childrearing lately (and I highly recommend primatologist Meredith Small’s Our Babies, Ourselves). With that so much on my mind of la........ Read more »

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