Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
If you happen to be awake, or are in Australia, have a look at the BearCam at Brooks Falls. Four Alaskan brown bears are in the rapids hunting salmon. And they’re spaced quite evenly.
It’s amazing we can watch this from the comfort of our homes.
Speaking of bears, here’s a video that’s gone viral this weekend. HuffPo gives the story:
A mama bear’s three baby bears got stuck in a dumpster recently, and it was a couple that came to the rescue.
The mama bear stayed up all night by the dumpster listening to her cubs cry, until Ruidoso, New Mexico couple Tom and Shirley Schenk arrived at light in their pickup truck with a ladder after hearing the bear cries as well.
“They know how to open the latch to the dumpster,” Shirley tells ABC News. “This mother is notorious in the neighborhood.”
While Tom backed the truck up to the dumpster — with Mama bear watching — Shirley lowered the ladder into the dumpster.
“I was not scared,” she says. “I had my husband driving and I knew we’d drop it and go. … I would have never done that on foot.”
Kudos to those nice Schenks!
Here’s the second “unanswered question of evolutionary biology” that I discussed in my BBC Focus piece (#1 is here). This one appears only in print, so I’ll put my answer online.
Why is there sex? It’s possible to reproduce without sex: many species do it, including microorganisms, lizards, fish, and plants. In fact, it turns out that reproducing asexually has a big evolutionary advantage. Imagine that each human couple can leave two offspring: on average one male and one female. If a female had a mutation that allowed her to reproduce asexually, she would have a tremendous evolutionary advantage. In the next generation, such asexual females would produce two females instead of one, meaning that our asexual females would effectively have double the reproductive rate of their sexual neighbors. Sexual females (and their male offspring) would therefore eventually be crowded out. This disadvantage of sexuality is often called the “twofold cost of sex,” but it’s really the cost of producing males who can’t bear children.
Despite this cost, the vast majority of species on Earth reproduce sexually. Why? There must be some big evolutionary advantage of sex that offsets the cost of producing those useless males. Evolutionists have offered many suggestions, but it’s not clear that any of them provides a sufficient advantage to overcome that two-fold cost.
One promising explanation involves parasites and pathogens. Every plant and animal is afflicted with these burdens, and natural selection favors the evolution of resistance. Yet pathogens themselves evolve to defeat these defenses, yielding a never-ending evolutionary “arms race” between hosts and parasites. Asexual hosts can’t respond quickly because their offspring are genetically identical to the parents, lacking the variation that fuels evolution. Sexuality gives you a leg up, however, because you can produce genetically variable offspring by mixing and shuffling your genes with someone else’s. Indeed, there’s some evidence that sex helps adapt to disease: lab experiments with microscopic worms, for example, show that sexual strains will outcompete asexual ones, but only in the presence of infectious bacteria.
Is this a general explanation? Once again we’re stymied by evolution’s historical nature. Even if the presence of parasites can account for sex in contemporary populations, it does not necessarily follow that this was the reason why sex first arose. Sex is, in fact, a surprisingly tricky problem.
Actually there are several possible answers to the conundrum of sex, but I had space to highlight just one.
This is awesome: a live webcam from Brooks Falls, Alaska, where the salmon are running at Katmai National Park. And the bears are in the water being avid piscivores. Don’t miss this one!
Read more about the webcams (there are four) at boston.com.
One camera is at Brooks Falls, where the bigger male bears compete for salmon, some while the fish are trying to jump the falls. The bears eat mostly the brains and eggs of these fish and let the carcasses flow downstream. This is the prime viewing area now.
The second camera is about 150 yards away, where females and cubs eat the fish scraps floating downstream. The third is at the lower falls, where bears will congregate later this summer when dead salmon float downstream after spawning. “Any bear can catch them when they’re dead,” Wood said.
The fourth is on Dumpling Mountain and provides an aerial view of the entire ecosystem, including Brooks Lake, Naknek Lake, Brooks River and falls, and in the distance the Valley of 10,000 Smokes, Damata said.
“The placement of the cams is fantastic,” Wood said. “I mean, they’ll be close enough, many of the bears you’ll be able to identity and follow the individual bears as they use the salmon at Brooks Falls and raise their young here.”
A screenshot:
h/t: Greg Mayer via Andrew Sullivan (!)
In the past 500 years, humanity has come a long distance in the way we treat children, women, animals, those of other faiths, and members of other cultures; see Steve Pinker’s superb new book, The Better Angels of Our Nature, for the documentation. A graphic example of this progress comes from a new paper in PLoS ONE by Angelique Corthals et al. (free download). It’s about infections in children ritually sacrificed by the Incas.
In 1999, a group of archaeologists discovered the preserved bodies of three children near the summit of a high volcano in Argentina. Dating back about five centuries, they included a 6-year old girl, a 7-year old boy, and a 15-year old girl. All of them had been sacrificed to the gods by the horrible practice of capacocha, as described by Wikipedia:
Capacocha was the Inca practice of human sacrifice, mainly using children. The Incas performed child sacrifices during or after important events, such as the death of the Sapa Inca (emperor) or during a famine. Children were selected as sacrificial victims as they were considered to be the purest of beings. These children were also physically perfect and healthy, because they were the best the people could present to their gods. The victims may be as young as 6 and as old as 15.
Months or even years before the sacrifice pilgrimage, the children were fattened up. Their diets were those of the elite, consisting of maize and animal proteins. They dressed the children in fine clothing and jewelry and escorted them to Cuzco to meet the emperor where a feast was held in their honor. More than 100 precious ornaments were found to be buried with these children in the burial site.
The Incan high priests took the victims to high mountaintops for sacrifice. As the journey was extremely long and arduous, especially so for the younger victims, coca leaves were fed to them to aid them in their breathing so as to allow them to reach the burial site alive. Upon reaching the burial site, the children were given an intoxicating drink to minimize pain, fear, and resistance, then killed them either by strangulation, a blow to their head or by leaving them to lose consciousness in the extreme cold and die of exposure.
The bodies had been exceptionally well preserved over five centuries because they were buried 20 cm underground in freezing temperatures, and the tombs packed with volcanic ash and covered with compacted snow.
Here are three photos taken from the paper; the caption is “a) La Doncella (the Maiden); b) El Niño (the Boy); and c) La Niña (the Girl)”. The Maiden was the 15-year old, and the one studied for infection. Her hair is finely braided. You’ll find these pictures ineffably moving; they look just like children from modern Peru:
Child sacrifice was not rare in pre-Columbian cultures. Here’s a description of an equally noxious practice of some Aztecs:
Archaeologists have found the remains of 42 children sacrificed to Tlaloc (and a few to Ehecátl Quetzalcóatl) in the offerings of the Great Pyramid of Tenochtitlan. In every case, the 42 children, mostly males aged around six, were suffering from serious cavities, abscesses or bone infections that would have been painful enough to make them cry continually. Tlaloc required the tears of the young so their tears would wet the earth. As a result, if children did not cry, the priests would sometimes tear off the children’s nails before the ritual sacrifice.
At any rate, the PLoS One paper involved an analysis of blood samples and mouth swabs of the mummies using “proteomics,” the practice of isolating proteins from body fluids and identifying them by mass spectrometry. I won’t describe the complicated procedure, which you can read about here, but the aim was to see whether the children carried infections (the youngest girl wasn’t sampled as her body had apparently been struck by lightning). There were preliminary signs that the older girl was indeed ill; as the paper notes:
Computed tomography (CT) scanning and radiological examinations of the Maiden revealed that all her organs, including the eyes and the brain, were intact. Both radiological and visual examination revealed pathologies consistent with a range of infectious diseases: 1) a radiolucent area in the upper lobe of the right lung, 2) a mucosal enlargement of the left maxillary sinus consistent with sinusitis, 3) a zoster-like lesion on the right calf, and 4) streaks of mucus under both nostrils.
The proteomic analysis showed several proteins in the Maiden (but not the boy) consistent with infection: proteins produced by the body to fight off microbes. Several of these indicated a pretty severe inflammation of the lungs, presumably by mycobacteria. This was confirmed by finding proteins from the Mycobacterium itself. Since Mycobacterium tuberculosis is one of the causes of tuberculosis, it’s possible that, even at age 15, she’d already contracted TB.
The question here may seem narrow, but does have broader implications, particularly in investigating via proteomics what diseases afflicted ancient people. Proteins can last a lot longer than DNA, and are less subject to contamination, so looking at the proteins of both pathogen and host (i.e., those proteins involved in the host’s immune response) can tell us about the health of our ancestors. The authors also note that the technique can help identify the state of infection from analysis of blood in modern criminal cases, which I suppose can sometimes be useful.
But what stays with me after having read the paper are the photos of the children, needlessly slaughtered—as were so many adults—in the name of a nonexistent deity. Religion has poisoned everything for a long time.
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Corthals A, Koller A, Martin DW, Rieger R, Chen EI, et al. (2012) Detecting the Immune System Response of a 500 Year-Old Inca Mummy. PLoS ONE 7(7): e41244. doi:10.1371/journal.pone.0041244
UPDATE: A reader pointed out, and the Alaska Dispatch seems to verify, that this story is an elaborate hoax: Stubbs wasn’t really elected mayor at all. Well, maybe. But it’s still cool, as he does holds court at the store and sips catnip-flavored water from a wine glass. Now if that part is phony, I give up.
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About two years ago, in Alaska to lecture, I drove up to Talkeetna, a small town near Denali National Park, site of Mt. McKinley, the highest mountain in North America. Talkeetna is the jumping-off spot for climbers and visitors to Mount McKinley, since you can hire small planes to either take you to the base camp or get an eagle’s-eye view of Mt. McKinley. I did the latter, with the bonus of landing on a glacier to deposit two climbers (see the link for photos, which include the airport cat).
Several readers have recently informed me that, as reported here by CNN, the mayor of Talkeetna is not a human, but a cat—a ginger tom named Stubbs. And he’s been mayor for 15 years, holding court from Talkeetna’s general store. (I visited that store and at the time was tragically unaware of Stubb’s presence). The CNN piece is hilarious:
For 15 years, Stubbs the cat has held the top office in Talkeetna, Alaska. And his approval ratings have never been higher.
“He doesn’t raise our taxes — we have no sales tax. He doesn’t interfere with business. He’s honest,” said Lauri Stec, manager of Nagley’s General Store, which doubles as the mayor’s office.
Stubbs may be the only mayor in the country who rose to office as an infant.
“He was in a box full of kittens in the front of the store, and (the owners) were giving them away,” Stec said. She picked “Stubbs” because he had no tail.
Talkeetna doesn’t need a human mayor because it’s so tiny: just one street with a few businesses, really, and the airstrip. Nevertheless, Stubbs runs a tight ship:
“All throughout the day I have to take care of the mayor. He’s very demanding,” said Skye Farrar, a clerk at Nagley’s. “He meowed and meowed and meowed and demanded to be picked up and put on the counter. And he demanded to be taken away from the tourists. Then he had his long, afternoon nap.”
In addition, the mayor will only drink water from a wine glass that has catnip in it, Stec added. [This is shown in the video below!]
But most everyone is willing to put up with the mayor’s high-maintenance lifestyle, especially because he’s a big tourist attraction for the community of about 800 human beings.
Here’s a video report on Stubbs, and, as you might expect, he has a Facebook page:
I don’t share Ayn Rand‘s deification of egoism and untrammeled capitalism, though I was briefly enamored with “objectivism” as a teenager (who wasn’t?). Nevertheless, her emphasis on the use of reason made her a passionate opponent of religion. Here’s a five-minute clip of her defending atheism on three television programs. I don’t recognize the first show, but I think the host of the second is Phil Donohue. As a reader below notes, the third is Tom Snyder.
h/t: PN
In April I was asked by the BBC’s science magazine, BBC Focus, to provide them with a short essay identifying and discussing some major unanswered questions in evolutionary biology. (This is part of their regular “Questions at the Frontiers of Science” series.) I identified three, and at my request the magazine has kindly put one of them online for my readers. The question is “Was the course of evolution inevitable?”, and you can read my answer here.
In the next two days I’ll post the other two questions and my answers; these are available only in the print magazine but I’d like to give readers to have a chance to see them. Alternatively, since there was some editing of what I submitted, if you email me I’ll send you a Word document with my original questions and answers.
One issue that I didn’t tackle was the thorny problem of how the first organism (or replicator) came into being. There’s not much to be said here yet: we have lots of hypotheses but are approaching the answer only slowly. (Do note, though, that studies of the origin of life, or “abiogenesis” aren’t formally part of evolution, which takes over only when a replicator has come into existence.) And even if we can produce life in the laboratory under conditions approximating those of the early Earth, that only shows us that it could have happened, not how it happened. Still, such a demonstration—and I think we’ll see one in the next 50 years—would go a long way toward blunting one of the few arguments left in the creationist arsenal. For it would dispel the main creationist claim about this issue: that there’s no way life could have originated spontaneously without the help of God.