Tag / hormones

by Roslyn

Does biology explain the sex ratio in tech?

Here’s what bugs me about James Damore’s recent anti-Google screed: it’s a terrible misuse of biology.

The question he addresses is: Why are there so few women in tech and tech leadership? In his memo to Google, Damore offered an explanation (note: I added the numbers):

On average, men and women biologically differ in many ways. These differences aren’t just socially constructed because:

(1) They’re universal across human cultures

(2) They often have clear biological causes and links to prenatal testosterone

(3) Biological males that were castrated at birth and raised as females often still identify and act like males

(4) The underlying traits are highly heritable

(5) They’re exactly what we would predict from an evolutionary psychology perspective

I’ll assume, for the sake of argument, that points (1)-(4) are more or less true.

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by Roslyn

A bad year for birds

June 2013 was bad for tree swallows. At the Queen’s University Biological Station, over 90% of nests failed as a result of persistent cold, rainy weather.

This happened to be the same year we were conducting an experiment on the hormonal mechanisms of parental care in these birds. The bad weather made for a disastrous field season. Just a couple of weeks in, and we were turning up cold lifeless chicks in nearly every nest. The upside was that it led to some potential insights into the way stress hormones and tough weather conditions interact. My coauthors Jenny Ouyang and Ádám Lendvai were invited to write an excellent blog post about it here:

Terrible weather provides insight into a bird’s life

It was remarkable how closely the nest failure rates tracked the fluctuating air temperature. This could be caused by a couple of factors, with a major one being that tree swallows rely on flying insects to feed their young, and the ability of insects to fly depends on temperature. Persistent cold weather means that parent tree swallows cannot find enough food to support their offspring.

The corticosterone hormone implants made the treatment birds more susceptible to faster brood mortality, even during benign weather. It should be noted that the implants were deployed before the bad weather struck, and we would not have performed this experiment if we had known in advance that this would be such a tough year! Hopefully, though, the results provide some insight into the role of stress hormones as mediators of a sensitive period in the life history of these birds.

Read the study here:

Ouyang et al. 2015. Weathering the storm: parental effort and experimental manipulation of stress hormones predict brood survival

by Roslyn

Not when cupid strikes

Raphael's The Triumph of Galatea

“Not when cupid strikes.”

That was Christine Drea’s response at the Animal Behavior meeting last summer. She had just given a talk on her latest study, showing the dramatic effects of hormonal contraception on the way lemurs communicate with the opposite sex1. I was asking her what advice she gives to women about birth control. On the 50th anniversary of the Pill, scientists like Drea were adding to the evidence that we might want to think twice about our widespread use of these drugs. The lemur research suggests that hormonal contraception could be replacing one “problem that has no name” – Betty Friedan’s idea of the dissatisfaction felt by modern women – with another2.

Like many primates, ring-tailed lemurs have a complicated system of signaling to one another through scent. Males are able to detect the sex, fertility and even the identity of a particular female by smell alone3. At first glance, the connection to humans might seem far-fetched, since our noses are pretty poor compared to other mammals. But we are relatively well-endowed when it comes to scent production: humans have more scent glands on the surface of our skin than any other primate4.

We also have some surprising olfactory abilities lurking beneath the surface. The classic example is the T-shirt test. In the 1990s, researchers at the University of Bern in Switzerland gave a group of men T-shirts to take home, with instructions to sleep and sweat in them over the next two nights5. When women were later asked to sort the dirty T-shirts based on pleasantness of smell, they did something surprising. Their rankings came down to genes: the more genetically distinct a man was from a female rater, the more she liked his scent.

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