Stories tagged heredity

Dec
23
2008

Prejudice against the rural poor: Well, sure, but a fictional rural poor. This gentleman is an urban musician who shops at trendy surplus stores, and it's too difficult to tell if his parents are closely related.
Prejudice against the rural poor: Well, sure, but a fictional rural poor. This gentleman is an urban musician who shops at trendy surplus stores, and it's too difficult to tell if his parents are closely related.Courtesy Poodleface
Well, Buzzketeers, we’re in the thick of the holiday season now—wading through that sticky caramel center of winter festivities, thigh-deep in a swamp of sweater clad relatives, up to our necks in mixed metaphors…

And, you know what? I hope you dig it. That’s my gift to y’all: the honest wish that you are all enjoying your elbow to elbow time with your closest kin. There’s your non-denominational seasonal gift, everyone, I hope you like it. (Personally I celebrate “Wintermania,” during which my family falls into a Wham!-induced frenzy, and then sacrifices anything to our winter deities. We come out of it with a lot fewer pets and household appliances, but it’s an exciting and high-spirited occasion. But I won’t force my beliefs on you.)

There’s some extra thought behind my gift, though. I mean, I know you’ll like it anyway, but it’s practical too! See, it just might happen that, someday, you’ll be bumping more than elbows with your cousins, and working your way up to that may start with the holiday conviviality. So you’re welcome for my making your life easier.

“What?” you say. “I’m not doing… that… with my cousin!”

Nor should you, sensitive Buzzketeer, nor should you. Necessarily.

But you could. Generally not legally, of course. But it turns out that, genetically, the whole “kissin’ cousins” thing might not be as problematic as you have been lead to believe. So says a new article on population genetics in the journal PLoS Biology.

See, the thing about serious inbreeding with close relatives is that it drains your gene pool—it reduces the variety of genes in your offspring. There are a couple reasons to have a nice assortment of genetic traits in a population. If everyone is the same genetically, then they all have the same genetic vulnerabilities, and something like a specialized disease or an abrupt change in the environment could wipe out the whole group. Also, and here’s the kissin’ cousins problem, a lot of genetic disorders result from having two recessive genes matched up in your DNA. If you just have one recessive gene for a disorder, you won’t develop the disorder, but you could pass that gene on to your kid, and if the kid got another copy of that recessive gene from his or her other parent, the kid would develop the disorder. People get disorders caused by matched recessive genes even when their parents aren’t related at all, but if a recessive gene for a particular disorder runs in a family, the chances that a kid in that family will get the gene from both parents is greatly increased if those parents are related.

That’s the idea, anyway. The folks who published this new article, however, say that, in reality, the chances that the offspring of two cousins will have birth defects (caused by recessive genes pairing up) really isn’t as great as most of us think. Specifically, the odds that two cousins would produce a child with congenital defects are only 1-2% greater than those for the rest of the un-related, child-producing population. Women over 40 have a similar risk of having children with congenital defects, the researchers point out, and there are no laws prohibiting them from having kids, whereas 31 states have laws against cousins being married. Laws like these, they say, aren’t based in solid science and reflect “outmoded prejudices about immigrants and the rural poor.”

So there. Do with your present what you will. Try it on for size, or give it to someone else—you won’t hurt my feelings. Merry Wintermania!

Oct
29
2008

He can teach you much, but give you nothing: Wait... Is this man even handsome? This IS complicated!
He can teach you much, but give you nothing: Wait... Is this man even handsome? This IS complicated!Courtesy monseurlam
Sorry to break it to you, dudes, but you aren’t just ugly ducklings—you’re just ugly. Or, if you are mirror-melting hot, those good looks are an invention all of your own, so skip the father’s day present, and get yourself something nice.

See, guys and boys, you’re dad may have taught you how to gut a possum, and he might even have given you your first possum-gutting knife, but he didn’t give you the looks that attracted all those hungry eyes at the possum market. He saved those for your sister.

It turns out that men don’t inherit their fathers’ “attractiveness”. Fathers do pass on masculine features to their sons, but there doesn’t seem to be any strong correlation between attractive fathers (or, technically, “hot dads”) and attractive sons. So says the journal Animal Behaviour.

By rating the images of hundreds of males and females, and their respective parents, the recent study hoped to test the theory that women seek out attractive mates to produce sexy male offspring, who will in turn pass on their mother’s genes.

Uh uh. The study found that hot dads didn’t necessarily have hot boys, and that unattractive fathers (or “ug dads”) didn’t necessarily have ug boys. In fact, the study found no evidence of male-to-male attractiveness inheritance at all. So that beautiful bone structure, those sparkling eyes, that indefinable something that makes you so, so foxy… where did that come from? Your mother, perhaps?

Nope, attractiveness doesn’t seem to come from your mom either. It seems that when boys are born, they’re cast out into the Land of Fug to fend for themselves, and if they find a sunny hilltop to build a face on, they have to do it on their own.

Mothers, the study found, do pass on attractiveness to their daughters. And, ironically, so do fathers—hot dads are likely to have attractive daughters. That means that daughters are getting all those good looks funneled into them from both sides! Ooooh, I hate them so much!

It’s like the legend of Puss in Boots, really. The wealthy old miller and his wife (who I believe was some sort of novelty hat heiress) were on their deathbeds at the same time (food poisoning, I believe), and were deciding how to divvy up their vast wealth between their two sons and one daughter. Keep in mind, this was before division was invented, so the two dying parents decided that the fairest thing to do would be to give all their money to the daughter and none to the sons. The daughter lived a long and very happy life, and no more needs to be said about her. One of the sons died more or less on the spot (food poisoning, I believe), and the other grabbed the miller’s cat and did a runner.

The stolen cat may or may not have had a plan for the surviving son’s well-being, but there was no way to tell, because the cat couldn’t speak English, and the son couldn’t speak Cat. So, making the best of what he had, the son forgot to feed the cat until it died, and then took its fur. (And this was clever in itself, because the son was still too poor to afford a knife, and he had to be creative—that’s where the saying “there’s more than one way to skin a cat” comes from.) The son then used the beautiful fur (it was a good cat) to make an attractive fur hat (a skill he learned from his mother), which he sold to a local eccentric. The profits from the sale were then invested in the construction of a new animal shelter/hat factory. The venture proved to be a lucrative one, and it kept the man in stockings and gin for the rest of his life, until he burned the factory down so that his own son couldn’t inherit it.

Do you see the connection? If you replace all references to money in the story with the word “hotness,” the analogy is particularly apt.

Jun
20
2008

For decades, scientists have been growing microbes in their labs and watching them evolve new traits. Most of the changes tend to be simple things, like an increase in size or growth rate.

But Dr. Richard Lenski of Michigan State University (just 2 miles from my house!) recently witnessed a major evolutionary leap--as it was happening. Twenty years ago, he took a colony of E. coli, a common bacteria, and split it into 12 identical populations. He’s been watching ever since to see if the strains evolve in different directions.

A few years ago, one of them did. One of his study strains suddenly evolved the ability to eat citrate, a molecule found in citrus fruits. No other E. coli in the world can do this, not even the other strains in Dr. Lenski’s lab. Even given several extra years and thousands of extra generations, the other strains are still citrate-averse. What’s more, the bacteria evolved this mutation entirely on their own, without any prodding or genetic manipulation from the researchers.

Lenski had saved frozen reference samples of all of his strains at regular intervals. Going back and growing new cultures from these samples, he again finds that only those from one strain ever evolve the citrate-eating habit – and only those sample less than about 10 years old. Lenski figures that some mutation happened around that time in one strain – and one strain only – that would later lead to citrate eating. He and his lab are now working on figuring out exactly what that mutation is.