Genetics

From “What Can Twins Tell Us About Mate Choice?” (ScienceDaily, Apr. 26, 2011), we learn:

What factors influence our choice of a mate? Is it our genes? Does a man look for someone like his mother and a woman someone her father? None of the above, according to a study of Australian twins.

Body size, personality, age, social attitudes, and religiosity played little role in identical twins’ choice, but get this:

A twin’s spouse was much more similar to the twin and co-twin than the twin’s opposite-sex parent.

That suggests that the strong influence is actually the family environment. The identical twin would be more highly motivated than most people to seek out someone who is “like me.” Singletons consider ourselves lucky to get “someone who understands me.”

Twin studies should be taken with a gallon of salt anyway:  Read More ›

A friend put me onto this human genetic research program (no, no, it all sounds reasonable, keep your shirt on; no one is looking for the  missing link andyou are him and the genetic police are waiting outside … wake UP, will you?): Ethnically diverse people are donating DNA to science, and the wealth of genomic data emerging from the project already is shedding light on human evolution.A decade ago it was a big deal to spell out the entire DNA sequence of a single human being. That event marked the success of the initial Human Genome Project. Now hundreds of human genomes have been decoded. Scientists who study human evolution are using the new data to make discoveries about how Read More ›

We are in the midst of a paradigm shift in our understanding of how evolution can act…on evolution, yielding mechanisms that allow both adaptation and heritability within the course of a lifetime. And such paradigm shifts almost always have societal consequences. Manel Esteller shows that epigenetics also impacts the “dark genome” in a way that may improve cancer diagnostics. So says Andrew D. Ellington in “Epigenetics and Society: Did Erasmus Darwin foreshadow the tweaking of his grandson’s paradigm?”(The Scientist, Volume 25 | Issue 3 | Page 14). He means, roughly, a revival of Lamarckism, the idea that life forms can acquire genetic information from their environment as well as through Darwin’s natural selection acting on random mutation. Why that was Read More ›

As Globe & Mail medical reporter Carolyn Abraham tells it (February 25, 2011):

Since James Van Gundia Neel proposed it almost 50 years ago, the thrifty-gene hypothesis has reigned as the dominant explanation for soaring rates of obesity and diabetes among many aboriginal groups. Native communities where diabetes didn’t exist in the first half of the 20th century had, by the end of it, the world’s highest prevalence, with Arizona’s Pima Indians in first place, followed by the Nauru islanders of Micronesia and the Oji-Cree at Sandy Lake.Dr. Neel, an influential geneticist at the University of Michigan, felt that genes were partly to blame. He speculated that genetic traits among the world’s prehistoric hunter-gatherers enabled them to store calories during times of feast in order to survive in times of famine.

But with “the blessings of civilization,” he wrote, these thrifty genes had become hazardous baggage in a sedentary world of all feast and no famine, predisposing carriers to obesity and the diseases it brings.

His idea spread like an epidemic, embraced by everyone from public-health officials and policy-makers to the media and many aboriginal people themselves. Although never billed as more than a hypothesis, it came to be seen as fact – “a scientific axiom,” Dr. Hegele says, “dogma almost.”

But now, with obesity and diabetes shaping up to be a global pandemic, the theory appears to be dying – raising the prospect that prejudice more than proof gave it such a long life.

Why you should always be suspicious when you hear … what? Here’s what: When you hear any medical thesis whatever that is based on what “prehistoric hunter-gatherers” supposedly did.

You need to monitor three simple devices to track the growth of diabetes: Read More ›

Lab mice by Aaron Logan, Lightsource

In “Ma’s gene does different things to pa’s copy” Jessica Hamzelou (26 January 2011) reports for New Scientist on a knockout study of mice where researchers knocked out a gene called Grb10 in females and mated them with normal males.

(From the report: “Most of our genes are expressed in pairs – one copy inherited from each parent. But pairs of so-called imprinted genes have just one copy “switched on”.)

What happened? The gene was expressed “only in the brain and spinal cord.”* How did this influence behaviour?

Mice lacking the paternal gene groomed their mates so much that the latter lost their whiskers and fur.

So far so good. The gene helps regulate mouse behaviour. Now wait for the klunk:

Humans have the same gene, so there is a possibility that it might be influencing our own social behaviours, he adds.

“Possibility”,  “might” Their caution is well advised, but the question is, why bother? Humans differ from mice precisely in that we adjust our behaviour to real or perceived circumstances, and that difference greatly reduces the importance of any similarities.

If a human mother brushed her kid’s hair until it fell out, she would soon be in a supervised parenting program (at least where I live).

A study author comments, Read More ›