Feeds

Is it true that fewer boy babies are born in hard times?

Survival of the fittest

Intelligent flash storage arrays

Also in this week's column:

Is it true that fewer boy babies are born in hard times?

Asked by Jack O'Connor of Dublin, Ireland

The sex ratio of boy and girl births is affected by severe stressors such as earthquakes, tsunamis, environmental toxin contamination, political and social upheavals, and even serious downturns in the economy.

When society gets such a severe shock, the number of boy births falls and the number of girl births rises. A reduced number of boys are conceived and a higher number of boys die before birth.

The theory behind this is that natural selection favours female births when times are hard because, on average, females have a better chance of mating successfully than males. This principle seems to be followed in animals.

In 2003, evidence emerged that the same principle applies to humans. In an article in Human Reproduction that year, Dr Ralph Catalano, professor of public health at the University of California, Berkeley, presented an examination of birth records from Germany. Birth records reveal that in 1991, immediately following German reunification, the ratio of boys to girls in the former East Germany dropped to its lowest point since 1946, but then bounced back a year later. In the rest of Germany, where conditions were more stable, the boy/girl ration was unaffected.

In the same journal in September 2006, Dr Catalano has shown that the same odd occurrence happened in New York City after 9/11. The sex ratio of male births in New York City dropped in the period 1 January to 28 January 2002.

In addition, Dr Catalano has suggested that a male's life expectancy is affected by whether or not he was born in stressful times.

In the American Journal of Human Biology (e-published 12 October 2006), Dr Catalano and colleague Dr T Bruckner evaluate two rival theories accounting for this reduced male fetal morbidity. The first is the "damaged cohort" theory. This theory holds that a mother's response to the shocks of stressful times can trigger "stress reactivity" in the fetus and thereby shorten the lifespan of males in utero.

The second is the "culled cohort" theory. This theory holds that shocks of stressful times induce spontaneous abortions of frail male fetuses, but hardy male fetuses survive. Drs Catalano and Bruckner examine data from several northern European nations and conclude that there is more support for the "culled cohort" theory.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

Providing a secure and efficient Helpdesk

More from The Register

next story
SECRET U.S. 'SPACE WARPLANE' set to return from SPY MISSION
Robot minishuttle X-37B returns after almost 2 years in orbit
LOHAN crash lands on CNN
Overflies Die Welt en route to lively US news vid
You can crunch it all you like, but the answer is NOT always in the data
Hear that, 'data journalists'? Our analytics prof holds forth
Experts brand LOHAN's squeaky-clean box
Phytosanitary treatment renders Vulture 2 crate fit for export
No sail: NASA spikes Sunjammer
'Solar sail' demonstrator project binned
Carry On Cosmonaut: Willful Child is a poor taste Star Trek parody
Cringeworthy, crude and crass jokes abound in Steven Erikson’s sci-fi debut
Origins of SEXUAL INTERCOURSE fished out of SCOTTISH LAKE
Fossil find proves it first happened 385 million years ago
America's super-secret X-37B plane returns to Earth after nearly TWO YEARS aloft
674 days in space for US Air Force's mystery orbital vehicle
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.