Isegoria

Memory comes in many forms — long-term and short-term, “autobiographical,” “episodic,” and “semantic,” among others — Charles Murray notes (in Human Diversity: The Biology of Gender, Race, and Class), and females have an advantage in some of them (as Diane Halpern notes in Sex Differences in Cognitive Abilities):

• Females tend to be better than males at remembering faces and names.
• Females tend to be better than males at recognizing facial emotions.
• Females tend to be better at remembering the minutiae of an event (labeled peripheral detail), while males tend to be better at remembering the core events (labeled gist).
• Females tend to remember speech they have heard better than males, particularly when it relates to emotionally laden events in their past.
• Females tend to retain memories from earlier childhood better than males do.
• Females tend to have better short-term memory than males (e.g., given a list of single-digit numbers, they remember longer lists than males do).
• Females tend to have better verbal working memory (e.g., remembering a list of numbers while answering questions about an unrelated topic).
• Females tend to have better memory for locations of objects (e.g., remembering where the car keys were left).
• Males tend to have better visuospatial memory (e.g., navigating on the basis of a combination of landscape features).

In Human Diversity: The Biology of Gender, Race, and Class, Charles Murray continues his list of specific skills and aptitudes that each sex performs better, taken from Diane Halpern’s Sex Differences in Cognitive Abilities, with a look at perceptual-motor tasks:

• Females have an advantage on certain perceptual-motor tasks. On digit-symbol coding, for example, where each symbol corresponds to a number (e.g., “substitute 2 for #”), women code faster than men do.
• Females have an even larger advantage in a variety of fine motor skills involving hand-eye coordination.
• In tests of motor skills, it sometimes happens that men are faster but women are more accurate.
• Men have a substantial advantage in many large motor skills, but few of them have much to do with cognition. The major exception is males’ pronounced advantage on tasks that involve throwing objects accurately at stationary or moving targets, because that accuracy is highly dependent on visuospatial processing in the brain.

Throwing like a girl is definitely a thing.

In Human Diversity: The Biology of Gender, Race, and Class, Charles Murray relies on Diane Halpern’s fourth edition of Sex Differences in Cognitive Abilities (2012) for his list of specific skills and aptitudes that each sex performs better. He starts with sensory perception:

When it comes to the five senses — taste, touch, smell, sound, vision — the story is mostly one of small female advantages.

• Females tend to be better than males at detecting pure tones.
• Adult females tend to have more sensitive hearing for high frequencies than males.
• Females tend to have better auditory perception of binaural beats and otoacoustic emissions.
• Females tend to detect faint smells better than males.
• Females tend to identify smells more accurately than males.
• Males under 40 tend to detect small movements in their visual field better than females.
• Age-related loss of vision tends to occur about ten years earlier for females than for males.
• Males are many times more likely to be color-blind than females (the ratio varies by ethnic group).
• The balance of evidence indicates that females are more accurate than males in recognizing the basic tastes (sweet, sour, salty, bitter), though some studies find no difference.
• Females tend to be better than males at perceiving fine surface details by touch. This holds true for blind people as well as sighted ones.

Women are also more sensitive to pain and to disgust.

Gwern recently cited a paper, Attention and awareness in stage magic: turning tricks into research, that describes the neural basis of spoon bending and the dancing bar illusion:

Spoon bending. In this illusion the magician bends a spoon, apparently by using the power of the mind. In one part of the trick, the magician holds the spoon horizontally and shakes it up and down. This shows that the neck of the spoon has apparently become flexible. The apparent rubberiness of the spoon is an example of the Dancing Bar (or Rubber Tree) illusion, in which an oscillating bar (or rubber tree) seems to bend when it is bounced rapidly. The neural basis of this illusion lies in the fact that end­stopped neurons (that is, neurons that respond both to motion and to the terminations of a stimulus’ edges, such as corners or the ends of lines) in the primary visual cortex (area V1) and the middle temporal visual area (area MT, also known as area V5) respond differently from non­end­stopped neurons to oscillating stimuli. This differential response results in an apparent spatial mislocalization between the ends of a stimulus and its centre, making a solid object look like it flexes in the middle.

Early in Human Diversity: The Biology of Gender, Race, and Class, Charles Murray notes that:

The explicit rejection of a role for biology in the social sciences occurred from the end of the nineteenth through the beginning of the twentieth centuries, with the leading roles played by Émile Durkheim in sociology, Franz Boas in anthropology, and John Watson in psychology.

I didn’t immediately recognize John Watson. He was the American psychologist who established the psychological school of behaviorism — and I think he had his reasons:

Watson was born in Travelers Rest, South Carolina, to Pickens Butler and Emma Kesiah (née Roe) Watson. His mother, Emma Watson, a very religious woman who adhered to prohibitions against drinking, smoking, and dancing, named Watson after a prominent Baptist minister in hopes that it would help him receive the call to preach the Gospel. In bringing him up, she subjected Watson to harsh religious training that later led him to develop a lifelong antipathy toward all forms of religion and to become an atheist. His alcoholic father left the family to live with two Indian women when Watson was 13 years old (a transgression which Watson never forgave).

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Despite his poor academic performance and having been arrested twice during high school (first for fighting, then for discharging firearms within city limits), Watson was able to use his mother’s connections to gain admission to Furman University in Greenville, South Carolina.

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John B. Watson married Mary Ickes, a sister of Harold L. Ickes, while he was in graduate school. They had two children, also named John and Mary Ickes Watson. The younger Mary’s husband was Paul Hartley, and their daughter is the actress, bipolar disorder advocate, and founder of the American Foundation for Suicide Prevention, Mariette Hartley.

John B. Watson’s wife Mary later sought divorce due to his ongoing affair with his student, Rosalie Rayner (1898–1935). Watson’s affair had become front-page news during divorce proceedings in the Baltimore newspapers. Mary Ickes Watson, his wife, had searched Rayner’s bedroom. She discovered love letters Watson had written to Rayner. In October 1920, Johns Hopkins University asked Watson to leave his faculty position because of publicity surrounding the affair.

After the divorce was finalized, Watson and Rayner married in 1920 in New Jersey. They remained together until her death in 1935. John and Rosalie had two children, William Rayner Watson (1921) and James Broadus Watson (1924), and they raised them with behaviorist principles that John believed in. Like their half-sister, Mary, both sons also later attempted suicide. William died of suicide in 1954.

Pest managers are 30 years ahead of oncologists:

Robert Gatenby, the co-founder of Florida-based Moffitt Cancer Center’s new Center of Excellence for Evolutionary Therapy, is a pioneer in the field and driving the bulk of the work in the U.S. on adaptive therapy. He is also a co-author on a small, pilot study, with initial results published in 2017 in Nature Communications, that showed that patients lasted at least 27 months on average without their tumors growing, compared with the usual 16.5 months, while receiving less of the same drug.

Dr. Gatenby, who had a background in physics before going into medicine, often points to pest control to describe therapy, and others in the field have picked up the analogy as well. In pest management, managers often don’t try to eliminate all of the insects but instead reduce their numbers, keeping the spray-sensitive bugs around to compete against the resistant bugs. Pest management developed the technique after overusing insecticides, which eliminated most of the insects. But some resistant bugs came crawling back.

In terms of infections, it’s bacteria, parasites, and viruses that kill us, but fungi are responsible for 72% of the local extinctions of animals and 64% among plants:

Unlike viruses and most bacteria, fungi can survive — and survive for years — in dry or frigid environments outside of hosts. All they need to do is make spores: small, hardy reproductive structures containing all the necessary DNA to grow a new fungus. As spores, fungi can tough out adverse conditions and drift thousands of miles in the wind to find more livable settings.

Aspergillus sydowii, for example, hitches a ride in dust storms from Africa to the Caribbean, where it infects coral reefs. They’re also ubiquitous in the air; there are one to ten spores in every breath you take.

Wheat stem rust, a common fungus that causes $60 billion of crop damage a year, produces up to 10¹¹ spores per hectare, and they can travel 10,000 kilometers through the atmosphere to find new hosts. That’s only taking into account one of its five spore forms, which are produced at different times in its life cycle.

For plants in general, fungi are the number one infectious threat, far above bacteria or viruses. Many fungi are also generalists that use a scorched-earth strategy to parasitize a wide range of hosts. To invade host cells, viruses need to sneak their way in by fitting into specific proteins like a key in a lock. Because viruses need to have this precision, it’s hard for them to jump from one species to another one with a different set of proteins, and it’s a big deal when it does happen. Fungi, on the hand, don’t need to enter cells; like the mold that eats your bread, it squirts its digestives juices and rots everything in sight. While viruses nimbly pick your locks, fungi are like a bomb that will blow up your door — or anyone else’s.

Being generalists has another added bonus for fungal pathogens: They can completely wipe out a main host while living in other species as backup. For bacteria or viruses, killing an entire species is usually a bad bet for survival; get rid of your host and you’ve got nowhere to go yourself. In contrast, the fungus Batrachochytrium dendrobatidis, which eats away at the skin of amphibians, is able to infect 508 different organisms, killing 100% of some species but lurking in others without doing much harm. The unaffected species act as reservoirs that can harbor and even spread B.dendrobatidis as it “looks” for other hosts.

Some fungi can also lie in wait in the environment, not as spores but as living fungi that feed on decaying matter. For example, the fungus that causes white nose syndrome, Geomyces destructans, has been recovered in the soil in bat caves, and scientists think that it lurks in caves during the summer, surviving off of nutrients in the dirt and bat guano (droppings). The fungus can only infect hibernating bats, so it must live outside of its host for the majority of the year. Come winter, bats go into hibernation and the infection cycle starts again. G. destructans, too, is extremely deadly, killing 90% of the animals it infects or an estimated 6 million bats since it first appeared in North America in 2006. The fungus wakes bats up during their hibernation, which makes them burn out their fat reserves too quickly and starve to death.

That G. destructans can only infect bats during hibernation is a clue to the key reason we don’t have much to fear from fungal infections. During hibernation, the normally warm-blooded bats drop their body temperatures significantly to save energy — and that’s when G. destructans attacks. Fungi in general just don’t like high temperatures. A 2009 analysis of 4,802 fungal strains found that the number of surviving strains drops off rapidly as incubation temperature increased from 30° to 40° Celsius. The researchers suggest that fighting off fungus may be one reason why our body temperature is fastened at 37° C.

Microbiologist and immunologist Arturo Casadevall has even speculated that the anti-fungal protection of warm bodies may have been one of our ancestors’ advantages over the dinosaurs. In the aftermath of the massive plant die-off of the K-T extinction 65 million years ago, fungi likely thrived on plentiful rotting vegetation. As they proliferated, fungal diseases could have contributed to the selection pressure that killed off cold-blooded dinosaurs, opening the door for the ascent of warm-blooded mammals. Casadevall’s theory is speculative at this point, but the high virulence, adaptability, and transmissibility of modern fungi show why fending off fungal disease could have been quite advantageous for our fuzzy ancestors. So it seems we have warm-bloodedness to thank for protecting us from most pathogenic fungi, with a few exceptions.

(Hat tip to Gwern.)

In epidemiology, the basic reproduction number (denoted R₀, r nought) is the number of cases one case generates (on average over the course of its infectious period, in an otherwise uninfected population):

This metric is useful because it helps determine whether or not an infectious disease can spread through a population. The roots of the basic reproduction concept can be traced through the work of Alfred Lotka, Ronald Ross, and others, but its first modern application in epidemiology was by George MacDonald in 1952, who constructed population models of the spread of malaria.

When

R₀ < 1

the infection will die out in the long run. But if

R₀ > 1

the infection will be able to spread in a population.

Generally, the larger the value of R₀, the harder it is to control the epidemic. For simple models and a 100% effective vaccine, the proportion of the population that needs to be vaccinated to prevent sustained spread of the infection is given by 1 – 1/R₀.