The evolutionary level of human violence

There’s a new paper in Nature about the level of intraspecific violence in humans and other species, written by José Maria Gómez et al. (free reference and download below).  The question is how often members of single species kill each other in the wild, and whether humans are outliers. It’s already gotten a lot of attention in the press, including an Atlantic summary by Ed Yong, but I’ve avoided reading the journalism until I read the original paper. Now that I have, I’ll summarize the Nature paper briefly for those who haven’t seen other pieces about it.

First, the authors used data from the literature to estimate the level of lethal violence in 1024 species of mammals from 137 families. The question was this: what percentage of individuals who die within a species do so after interacting with members of their own species? That’s the measure the authors take as the degree of “lethal violence” within species. It does not include lethal violence from members of other species, like rabbits getting nicked by raptors.

When you impose that data on the known phylogeny (family tree) of mammals from genetic and morphological data, you can then, using techniques known for a while, estimate what degree of lethal violence existed in various species’ ancestors.  As a hypothetical example, imagine a group of ten related birds, nine of which have crests and one of which was uncrested. Assume further that we know from genetic data that those birds all had a single common ancestor and were all each other’s closest relatives (i.e. they’re a “monophyletic group”). If that’s the case, then it’s a reasonable assumption that that common ancestor also had a crest. (It’s more parsimonious to assume that the crest was lost once than that it evolved nine or so times independently in the descendants of an uncrested bird.) That’s a simple example, but you can use techniques like that to make quantitative estimates, too, and that’s what the authors did for lethal violence.

They first imposed measured levels of lethal violence on the known phylogeny of mammal species Here it is; the caption comes from the paper, and the color in a branch indicates the estimated level of violence in that branch, ranging from light yellow (peaceful) to dark red (violent). Click to enlarge, and notice the redness around carnivores and, especially, primates; more on that later:


Tree showing the phylogenetic estimation of the level of lethal aggression in mammals (n = 1,024 species) using stochastic mapping. Lethal aggression increases with the intensity of the colour, from yellow to dark red. Light grey indicates the absence of lethal aggression. Mammalian ancestral nodes compared with human lethal violence are shown in red, whereas main placental lineages are marked with black nodes. The red triangle indicates the phylogenetic position of humans.

The authors also found that related species tended to have related levels of violence. That’s what I would have expected, and when I read that sentence I thought, “Well of course: violence is more common in species that are more territorial as well as those that are more social, for territoriality and sociality breeds inter- and intragroup compeitition for mates, food, and territory. And of course if a species is social or territorial, its relatives are likely to be social and territorial.”

And, sure enough, there was a strong correlation between both sociality, territoriality, and violence among the species. Here’s a graph showing that, with territoriality seemingly inciting more violence than sociality:


(From paper): The figure shows the phylogenetically corrected level of lethal aggression per group (mean ± s.e.m) and the number of mammalian species included in each group. We used a phylogenetic generalized linear model (PGLS) to test the effect of territoriality (yes or no) and social behaviour (social or solitary) on lethal aggression. The level of lethal aggression was more intense in social and territorial species (PGLS, P < 0.05 in all cases and mammal phylogenies; Extended Data Table 1), with no interaction between these two terms (Extended Data Table 1).

Now what about our own lineage? Information about lethality was obtained from 600 human populations dating from the Paleolithic to the present, using both fossil (bone) and historical evidence. Lethal violence included homicide, cannibalism, war, infanticide, execution, and so on. Information was also available from H. neanderthalensis.  There are two main results:

  • The proportion of individuals in the genus Homo killed by lethal violence was about 2%, and this estimate is robust to things like the uncertainty of phylogenies. This is pretty high compared to some other animals (see below), but is explained by the fact that hominins are both social and territorial. This is the ancestral condition before we became civilized. These levels persist in many non-“civilized” groups, though, and from this the authors conclude that there is an evolved, genetically-based propensity for humans to be violent at a level that causes roughly 1 in 50 humans to be killed violently by other humans. That baseline level can be reduced by the imposition of law and “civilized” societies.
  • Violence is correlated with human social organization. The authors divided human groups into four types: “bands” (hunter-gatherers and the like), “tribes” (small groups that live in semipermanent places, with egalitarian societies composed of hunter/horticulturalists), “chiefdoms” (hierarchical non-industrial societies pervaded by kinship ties), and “states” (“politically organized complex societies”). Here are the data, which show that “historic” bands and tribes didn’t differ significantly from the phylogenetic “ancestral” level of violence, while historic chiefdoms and contemporary bands and tribes have significantly higher levels of violence than presumed in our ancestors. In contrast, both historic and contemporary states have considerably lower levels of violence than the ancestral estimate, probably (as the authors note) because in such societies the state takes over the imposition of violence. That, in fact, is one of Steve Pinker’s hypotheses in Better Angels for the historical decline in violence over the last five centuries.

Human lethal violence in different socio-political organizations28. In all cases the boxplots show median values, 50th percentile values (box outline), 95th percentile values (whiskers), and outlier values (circles). We tested whether the level of lethal violence observed in each ancestral node, human period and human socio-political organization differed significantly from the phylogenetic inferences in a.

Finally, I still haven’t read Ed Yong’s piece, though I will now, but I will reproduce a figure from his piece that someone put on Twi**er. It shows the level in violence among many species, and you’ll be surprised at the most violent:


Yes, the primates are up there, but Jebus, the most violent species is the MEERKAT, with over 19% of individuals killed by other meerkats. Who knew?


Vicious murderers!


Gómez, J. M., M. Verdú, A. González-Megías, and M. Méndez. 2016. The phylogenetic roots of human lethal violence. Nature, doi:10.1038/nature19758, Published online, 28 September 2016.

Donald Trump and taxes: did he do anything wrong?

I feel it essential to begin, as usual, with an asseveration that I despise Donald Trump and all that he stands for, that he appeals to the worst instincts in Americans, and that I will certainly vote for his opponent. But I also dislike the deification of Hillary Clinton—adulation that has gone so far that one is not allowed to criticize her lest, her adulators say, such criticism could help elect Trump. One friend of mine even wrote that she had a “storied career”! I respectfully disagree.

Does it become allowable to criticize a candidate we favor only after she’s elected? I don’t buy it. The same people who want to stifle criticism of Hillary Clinton also have said that it’s imperative that we criticize atheist “leaders” like Harris and Dawkins, for rationality demands that we hold those leaders as accountable as anyone else. If Clinton is elected (and I’ve put substantial money on the fact that she will be), we’ll just continue to hear the STFU trope about her, for she’ll in all probability be facing a Republican Congress. We can’t criticize her as it will just give fuel to those Republicans.

In fact, the Presidential campaign has become nasty on both sides (nastier on Trump’s), and this contributes to what I see as an irreversible polarization of American politics. Trump has no choice but to engage in negative politics, as he has no positive policies except for his execrable “wall” and the denigration of women, but it pains me to see Hillary Clinton engaging in those kind of politics. After all, she does have policies, and that is one thing that helped her during the last debate. But mud-slinging is the theme of the season, and it’s ugly.

Now we’ve heard that Donald Trump won’t release his tax returns, and that in fact he may have paid no taxes.  In his response during the debate, he said that paying no taxes made him “smart”.

The response, both from the public and the media, has been outrage. How could a multimillionaire pay no taxes, while the poor working stiff pays a big dollop of money to the government?

This criticism is misguided, and the outrage is faux outrage because it’s directed at the wrong target. So odious has Trump become that he now is the whipping boy for nearly everything, including the poor condition of America’s airports.

Everyone tries to minimize their tax burden, including me, using the legal provisions in the tax code. Seriously, how many of you refuse, for instance, to take your legal mortgage-interest or dependent deductions because you want to pay more than you have to to the government? If you do take legal deductions, you have no business criticizing Trump on this account. His taxes may reveal other malfeasance, and perhaps we’ll know eventually.

The fault lies not in Trump, but in a tax code that allows rich individuals and corporations to get away with paying almost nothing. And that is wrong, for of course all citizens have a duty to share in the burden of running the government, and of funding schools, roads, and other infrastructure.

But if you are outraged at Trump’s zero tax bill, then save your rancor for the government and its tax laws, not at him.

As for him not releasing his tax returns, I think that’s a mistake. Though it’s not mandated, it’s customary, and I suspect that he has something to hide beyond not paying any taxes. My suspicion is that his donations to charity are pitiful compared to what he should be giving, especially for someone who pays no taxes.


Readers’ wildlife photos (and a video)

If you’ve sent photos, I have them, so please be patient and I’ll let you know when yours are up.  Today we’re featuring more photos taken by Lou Jost on his recent visit to the Tambopata National Reserve in the Peruvian Amazon.

I’ve just come back from a visit to a remote part of the Peruvian Amazon, which humans have not yet messed up too badly (though they are trying hard). Big animals and birds that are rare and shy near humans are abundant and unafraid here.

One morning a Black-and-white Hawk-Eagle (Spizaetus melanoleucus) was soaring near the clay bank we were watching. It flushed all the macaws and parrots, and all three species of macaws then flew towards the eagle and seemed to try to drive it away from the area. But the eagle dived at one of the Red-and-green Macaws (Ara chloropterus), which briefly rolled upside-down to defend itself. The eagle continued to pursue this individual, but a Blue-and-yellow Macaw (Ara ararauna) went after the eagle, which looked backwards and screamed at it, while the potential victim escaped. I wished Stephen Barnard had been here with his big guns; these were just dots in the distance that sometimes accidentally came into focus in my little Lumix FZ300. I didn’t know what I was photographing until I reviewed the pictures. Sorry about the quality, but this kind of interaction is rarely photographed so I thought it was worth including.

Scarlet Macaws escort their enemy away

Black-and-white Hawk-eagle turns on the Red-and-green Macaws; on

Black-and-white Hawk-eagle banks onto Red-and-green Macaw, which

Blue-and-yellow Macaw distracts the hawk-eagle from its pursuit

Another morning we arrived early at a clay lick expecting to find parrots, but the entire clay bank was covered by a rambunctious herd of White-lipped Peccaries (Tayassu pecari). These are large, aggressive wild pigs that have been known to tear jaguars apart. Meanwhile a hungry jaguar was following these herds at the reserve, as we found fresh jaguar tracks on top of the peccary tracks.

White-lipped Peccary herd at Rio Tambopata clay lick

White-lipped Peccaries at Rio Tambopata Clay Lick

And a video:

Friday: Hili dialogue

If you’re reading this, you made it through the week alive, though you’re 7 days closer to death. That’s the bad news; the good news (?) is that it’s National Mulled Cider day, so celebrate your sentience with a mug. I prefer a good hard cider, particularly an English cask cider served in a big mug or glass and having about 7% alcohol. It’s also the last day of September, so tomorrow I’ll be able to post Thomas Wolfe’s “ode to October.”

On this day in history, Babe Ruth hit his 60th home run of the 1927 season, a record not surpassed until Roger Maris hit 61 in 1961 (I saw him play that season). On this day in 1941, the Baba Yar massacre of Jews was completed in Kiev, and, in 1955, James Dean died in a road accident, crashing his sports car. He was only 24.  On this day in 2005, the Danish newspaper Jyllands-Posten published the “Muhammad cartoons” that brought so much rancor; it was, perhaps, the beginning of Regressive Leftism in the form of those Leftists who said the cartoons shouldn’t have been printed.

Notables born on this day include Hans Geiger (1882), Buddy Rich (1917), Deborah Kerr (1921; her performance in From Here to Eternity was superb), and Elie Wiesel (1928; he died this year), Johnny Mathis (1935). Those who died on this day include James Dean (see above), Patrick White (1990), and Barry Commoner (2012). Meanwhile in Dobrzyn, Hili is doing some of her awkward philosophizing. I wonder if she thinks love of cats isn’t reasonable?

Hili: What is philosophy?
A: Love of wisdom.
Hili: This is highly suspect because love is not reasonable.
In Polish:
Hili: Co to jest filozofia?
Ja: Miłość mądrości.
Hili: Podejrzane, miłość nie jest rozsądna.
And out in Winnipeg, where shoeshoes are de rigueur these days, we have two pictures of everyone’s favorite earless white cat. Gus’s staff writes:
The angle of the sun is getting lower as we head into the fall, it seemed like it was almost horizontal yesterday. The first picture strikes me as a polar bear pose. In the second picture, I like the way the sun lights up the individual bits of fur sticking out his side.

Damien, a baby kangaroo

I suppose this is a juvenile of the big red kangaroo, but Aussies can weigh in here. At any rate, it’s adorable:

HuffPo stupidity of the day

I can’t really find anything to admire about Donald Trump (except, perhaps, how he keeps his hair on), but it does bother me that many Democrats and organs like the HuffPo are obsessed with finding fault in his every statement. It’s an obsession, and an unhealthy one, for it’s turning our political system into a mutual hate-fest. And here’s one from HuffPo (click on the screenshot to go to the post). It’s followed by a quote from Trump:


Our airports are like from a Third World country,” Trump ranted. “You land at LaGuardia, you land at Kennedy, you land at LAX, you land at Newark, and you come in from Dubai and Qatar and you see these incredible ― you come in from China, you see these incredible airports, and you land ― we’ve become a Third World country.”

Now it is true that many U.S. airports (and I’m thinking of LaGuardia and Logan) are unpleasant, crowded, and don’t even have decent noms; other countries, like the Netherlands and Germany, do much better. So some U.S. airports do bespeak a third-world atmosphere. As far as our becoming a Third World country, well, that’s true hyperbole, and yet in many ways: child mortality, lack of public medical care, income inequality and so on, we are. But HuffPo, instead of trying to turn Trump into a Satan by attacking his every word, might concentrate more on stuff related to the campaign, particularly his stands (or, rather, non-stands) on the issues.

And I’ve discovered that HuffPo now puts this at the end of every article about Donald Trump. I guess it can’t allow readers to think for themselves:


A letter

I’m wicked busy today, so have a letter from my past:


Nick Cohen on the flaws of the “cultural appropriation” warriors

I keep saying that Nick Cohen is an Anglophonic treasure. In terms of his straightforwardness and adherence to classical rather than Regressive Leftism, he’s the closest thing we have to the late Christopher Hitchens. And everyone should read his two books You Can’t Read this Book: Censorship in an Age of Freedom and What’s Left?: How Liberals Lost Their Way.

In his column at Standpoint this week, Cohen has finally written about the Cultural Appropriation Wars, using as his springboard the fracas involving Lionel Shriver, a white woman who gave a talk at the Brisbane Writer’s Festival defending a writer’s prerogative to write about the lives of marginalized and oppressed people—indeed, about anybody. In response, the black Australian Muslim writer Yassmin Abdel-Maglied, mortally offended at what was not that provocative a talk, stalked out of Shriver’s talk in tears, and wrote a petulant screed in the Guardian about the dangers of culturally appropriating minority characters. I was strongly on Shriver’s side (see here, here and here for my posts on the story).

And so I’m pleased that Cohen agrees with me, and on several issues, including the right to try such writing, even if it fails, and on the notion that no group is homogeneous, and that there’s no culturally approved way to write about marginalized characters except to make them flawless heroes. And that would be a disaster for fiction, since everyone’s flawed and flaws, in fact, are what makes good fiction.

Just two excerpts of Cohen’s piece to whet your appetite. In the first, he shows how you just can’t win when trying to placate the social justice warriors. (I used to use that term but then stopped because I thought it was offensive to people who really were concerned about social justice instead of just promulgating purity tests and flaunting their own virtue and purity; but now I think I may adopt it again):

Jonathan Franzen said recently that, because he had few black friends, he would not dream of creating a black character. Notions of identity politics and cultural purity lead to segregation. Yet when Franzen acknowledged it, the same type of social justice warrior who criticised Shriver criticised him. None quite demanded that he must create black characters, but, as one said, his reprehensible admission had weakened the fight for “diversity and inclusion” — as if the two were synonymous.

And that is how the Left eats its own, a theme of Cohen’s book What’s Left. And in the final bit of his article, Cohen makes an argument for the right of cultural appropriation that I see as unassailable (I’ve put the telling bit in bold):

Given the passion behind the assaults on cultural appropriation, can we expect the appearance of culturally sensitive novels and dramas whose frightened writers confine themselves to their tribal homelands or apply for visas if they wish to stray beyond its borders. It’s possible, but unlikely.

Shriver asked who a writer should go to for permission to publish her story of a trans woman or Nigerian man, when no one had the authority to issue permission on behalf of others. When I wrote about freedom of speech, for instance, an editor wanted “a Muslim scholar” to assure him that a passage about the life of Muhammad was not “offensive” (by which he meant “not likely to get my office bombed”). A liberal Muslim activist said it was fine. If an Islamist or Salafist had read the book, he would have said the opposite.

The great failing of identity politics and arguments against cultural appropriation is they assume identities and cultures are islands with warships patrolling their coasts. Cultures mix. None exists that is not a hybrid except possibly in the Amazon rainforest. Not everyone in an ethnicity shares the same identity, and it is a rank prejudice to treat them as if they do. Freedom of the individual is the freedom not to have your autonomy denied by collectives who claim to speak on your behalf. In other words, there is no legitimate cultural authority to stamp a writer’s passport. [JAC: I’ve noted before that while some black writers criticized white author William Styron’s book The Confessions of Nat Turner, about a slave, other black writers praised the book.]

The logical conclusion of cultural appropriation is solipsism. For why stop at saying a person of one culture cannot appropriate the experience of another? By what right can I write about you, or you me? If no one can imagine or inquire about life in another culture, how can they do so about the life of another person? The self will then be the only subject. Solipsism may power the social justice warriors, who weep about how grievously their feelings have been offended. But it is unlikely to produce fiction even they will want to read.

We’re now past the time when blatant and invidious stereotypes can be counted as good fiction, and even if they are published, everyone has a right to criticize them. But nobody has the right to dictate what subjects—or what people—can and cannot be written about.


Nick Cohen

Google honors inventor of the ballpoint pen

Today’s Google Doodle honors the 117th birthday of the Hungarian inventor László József Bíró (1899-1995). From either his name or the Doodle you can guess that he invented the ballpoint pen.


Biró’s story from Wikipedia:

Bíró was born in Budapest, Hungary,[2] in 1899 into a Jewish family. He presented the first production of the ballpoint pen at the Budapest International Fair in 1931.[2] While working as a journalist in Hungary, he noticed that the ink used in newspaper printing dried quickly, leaving the paper dry and smudge-free. He tried using the same ink in a fountain pen but found that it would not flow into the tip, as it was too viscous. Working with his brother György,[1] a chemist, he developed a new tip consisting of a ball that was free to turn in a socket, and as it turned it would pick up ink from a cartridge and then roll to deposit it on the paper. Bíró patented the invention in Paris in 1938.

In 1943 the brothers moved to Argentina. On 10 June they filed another patent, issued in the US as US Patent 2,390,636,[3] and formed Biro Pens of Argentina (in Argentina the ballpoint pen is known as birome). This new design was licensed for production in the United Kingdom for supply to Royal Air Force aircrew, who found they worked much better than fountain pens at high altitude.[4][5]

In 1945 Marcel Bich bought the patent from Bíró for the pen, which soon became the main product of his Bic company.

And from the Torygraph:

The first major buyer of the newly created pen was the Royal Air Force. During the Second World War the organisation ordered 30,000 of the tools, which would work at high altitudes unlike traditional fountain pens. After the war it entered commercial production.

Today, the Bic Cristal biro is the world’s most popular pen. In the US, the price has remarkably stayed the same since 1959 – retailing at 19 cents despite inflation.

In Europe you can still hear these pens called “biros,” but that word is virtually unknown in the U.S., where they’re called ballpoint pens. Here’s an early ad:


And here’s Biró himself:


Now I’ve never liked writing with ballpoint pens. Earlier in my life I loved fountain pens, which made the act of writing a sensuous pleasure, and I eventually worked my way up to the King of Fountain Pens, the Montblanc Meisterstück. (I still have it, but it needs to be repaired.) I also had a Parker 75 in sterling silver. Over the past few years, though, I’ve graduated to the Uni-Ball micropoint pen, a sort of hybrid between ballpoints and fountain pen. The ink dries quickly and it has a very fine point, good for drawing cats in books. I also find that I write almost nothing by hand any more, and so my handwriting has degenerated a bit.

What do you write with?


Readers’ wildlife photographs

Reader Karen Bartelt sends picture of Giant Tortoises from the Galápagos, despite the variation, they are all subspecies of one species, Chelonidis nigraKaren describes them as Geochelone, which is the genus of the ancestral species from South America, but there may have been some taxonomic revision of the group.
It’s not easy to see tortoises in the wild.  I did see a small one on Isabella, but it was under a bunch of brush.  The place where one is guaranteed to see them is the Santa Cruz highlands.  Various farmers and landowners allow the tortoises to roam freely, and some offer “camps” where one can stay overnight.  The first three photos are domed tortoises from Santa Cruz, Geochelone nigrita.  
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The last three photos are saddlebacked tortoises at the Charles Darwin Research Center.  The first two photos show the tortoises recently recovered from the Wolf Volcano area on Isabella.  This is an exciting find, because these are hybrid (or even possibly pure) Pinta (Geochelone abingdoni; Lonesome George was thought to be the last) or Floreana (Geochelone galapagoensistortoises.  As such, they represent a possible mechanism for reintroducing the two extinct species.  They were found a few years ago.  The story we got is that after the holds of pirate or whaling were stuffed full of tortoises, these ships sometimes sank, or were sunk.  The lucky tortoises bobbed around until currents carried them to the northern tip of Isabella island, near Wolf Volcano.  Because tortoises can live over 200 years, it’s possible that some purebreds of the “extinct” species are still roaming around, and scientists are still looking.
The very last photo is of Diego, a saddlebacked tortoise originally from Espanola (Geochelone hoodensis).  He was returned from the San Diego Zoo in order to help reintroduce Espanola’s tortoise population.  After goats were extirpated from Espanola, Diego and two other males were mated with about a dozen females which had also been brought to the center.  By 2000, the 1000th young tortoise had been returned to Espanola, and Diego had fathered about half of them.  As of 2016, there is no longer a breeding program for Espanola tortoises, and the population is considered stable.  Diego is now a retired sex slave.
And we have two photos of fungi, a rarity here.  The first is from reader Christopher:
Here’s a lovely, slightly rude fungus for you, the Dog Stinkhorn, Mutinus ravenelii, that I found under some trees in a school courtyard in Kansas City, Missouri last week. Quit a few fungi appear a bit phallic, but this one and its relative, the appropriately named Phallus ravenelii really don’t require much imagination, at least for d*g owners.
And from Alexandra Moffatt:
Button mushrooms: Agaricus bisporus, I think. Seen in the New Hampshire woods so I am not sure; the book says they grow in grasslands. I liked the decorative, purposeful pattern and the appearance that suggests a fungal army attacking a castle.