Feeds

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

Survival of the fittest

The next step in data security

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

Choosing a cloud hosting partner with confidence

More from The Register

next story
SCREW YOU, Russia! NASA lobs $6.8bn at Boeing AND SpaceX to run space station taxis
Musk charging nearly half as much as Boeing for crew trips
Boffins say they've got Lithium batteries the wrong way around
Surprises at the nano-scale mean our ideas about how they charge could be all wrong
Thought that last dinosaur was BIG? This one's bloody ENORMOUS
Weighed several adult elephants, contend boffins
Edge Research Lab to tackle chilly LOHAN's final test flight
Our US allies to probe potential Vulture 2 servo freeze
Europe prepares to INVADE comet: Rosetta landing site chosen
No word yet on whether backup site is labelled 'K'
Cracked it - Vulture 2 power podule fires servos for 4 HOURS
Pixhawk avionics juice issue sorted, onwards to Spaceport America
City hidden beneath England's Stonehenge had HUMAN ABATTOIR. And a pub
Boozed-up ancients drank beer before tearing corpses apart
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Security and trust: The backbone of doing business over the internet
Explores the current state of website security and the contributions Symantec is making to help organizations protect critical data and build trust with customers.