Video on what exactly a gene is

There’s a video on the evidence for evolution going around, but turns out the artist that made that video has made a number of them, including this one on the scientific understanding of a gene.

via Videos / What Exactly is a Gene? – Stated Clearly.

What’s interesting about this, is that the definition of “gene” has changed over the decades.  As I understand it, when the word was originally coined, it meant a discrete unit of inheritance, but now it refers to a cistron, a discrete string of DNA encodings that only make up a small percentage of DNA overall, with the remainder initially receiving the nickname “junk DNA”.

As molecular biologists are learning more about DNA and inheritance, it’s becoming increasingly evident that these coding sequences aren’t the whole story, that vast swaths of what was thought was junk DNA are turning out to be part of the process, which is causing many to declare that genes aren’t the whole story.  And they’re not, using the modern definition.  But by the classic definition, which would include the sequences and any supporting framework in non-coding DNA, they arguably remain the main story.

Learning the smell of fear: Mothers teach babies their own fears via odor, animal study shows.

Some of the ways that mothers can teach offspring is pretty primal: Learning the smell of fear: Mothers teach babies their own fears via odor, animal study shows — ScienceDaily.

Babies can learn what to fear in the first days of life just by smelling the odor of their distressed mothers, new research suggests. And not just “natural” fears: If a mother experienced something before pregnancy that made her fear something specific, her baby will quickly learn to fear it too — through the odor she gives off when she feels fear.

In the first direct observation of this kind of fear transmission, a team of University of Michigan Medical School and New York University studied mother rats who had learned to fear the smell of peppermint — and showed how they “taught” this fear to their babies in their first days of life through their alarm odor released during distress.

This study reminds me of one I linked to a few months ago which appeared to show that mice could inherit a fear of smell from their father.  Both studies tried to address the actual phenomenon in humans where children sometimes inherit trauma about experiences that their parents had.

One difference between these studies is that in the earlier one, the offspring were never exposed to the smell until they were tested.  That seemed to show that they could only have inherited the fear of that smell genetically.  I thought I had remembered that the offspring in that earlier study were also isolated from their parents, but looking it over again, I don’t see that mentioned.  (I do see it mentioned that some of the offspring were conceived through in vitro fertilization, which does seem to imply isolation.)

The question is, which of these transmission mechanisms, communication of a parent’s fear to their baby through smell, or the apparent transmission of that fear through sperm or egg, is most relevant to the human phenomenon?

Going forward, he hopes to work with U-M researchers to observe human infants and their mothers — including U-M psychiatrist Maria Muzik, M.D. and psychologist Kate Rosenblum, Ph.D., who run a Women and Infants Mental Health clinic and research program and also work with military families. The program is currently seeking women and their children to take part in a range of studies.

The problem here will be in knowing that the transmission didn’t happen by the mechanism identified in the earlier study.  This will be difficult to determine in humans, since you can’t exactly isolate human children from their parents in the manner possible with animals (for obvious ethical reasons).

BBC – Future – How human culture influences our genetics

BBC has an interesting article on the effects of culture on evolution.

You shouldn’t be able to drink milk. Your ancestors couldn’t. It is only in the last 9,000 years that human adults have gained that ability without becoming ill. Children could manage it, but it was only when we turned to dairy farming that adults acquired the ability to properly digest milk.

It turns out that cultures with a history of dairy farming and milk drinking have a much higher frequency of lactose tolerance – and its associated gene – than those who don’t.

Drinking milk is just one of example of the way that traditions and cultural practices can influence the path of our evolution. Culture and genetics are traditionally thought of as two separate processes, but researchers are increasingly realising that they are intimately connected, each influencing the natural progression of the other. Scientists call it “gene-culture co-evolution.” Why does it matter? If we can pin down how culture influences our genetic makeup – and how the same processes apply to other creatures too – then we can be better understand how the way we act as a society today could influence our future.

more at BBC – Future – How human culture influences our genetics.

This makes a lot of sense if you think about it.  Culture is part of the environment in which natural selection works.

I’ve recently come to appreciate the fact that natural selection doesn’t necessarily mean those without the adaptive attribute died prematurely.  It could simply mean they were slightly less successful reproductively.  An imbalance which, over thousands of years, can lead to the adaptive trait dominating in a population.

This also reminds me of the research which seems to be showing that the development of our large brains is probably largely due to our social nature.  Being slightly more intelligent probably increased your ability to navigate social dynamics, giving you a slight reproductive edge.  Over hundreds of thousands of years, this is probably what led to a rapid increase (in terms of evolution time frames) in our species intelligence.

Humans and Neandertals interbred, new method confirms — ScienceDaily


Technical objections to the idea that Neandertals interbred with the ancestors of Eurasians have been overcome, thanks to a new genome analysis method. The technique can more confidently detect the genetic signatures of interbreeding than previous approaches and will be useful for evolutionary studies of other ancient or rare DNA samples.

via Humans and Neandertals interbred, new method confirms — ScienceDaily.

Well then, that’s that.  As someone who’s 3% Neandertal, I can say I’m fine with it.  It does seem to confirm that Neandertals must have been more like us than they’re often portrayed, since it’s unlikely either them or our ancestors would have been interested if we were too different.

Who’s afraid of math? Study finds some genetic factors

As someone who’s never been good at math, I found this particularly interesting.  It’s strange that I’ve always been in the top tier of programmers on any team I worked on, easily gotten As in any programming class I took, and that programmers as a general breed tend to be good at math, but I’ve always invariably sucked at it.  Go figure.

I have to admit that the idea of being able to blame it on my genes is appealing.

A new study of math anxiety shows how some people may be at greater risk to fear math not only because of negative experiences, but also because of genetic risks related to both general anxiety and math skills. The results don’t mean that math anxiety can be blamed solely or even mostly on genetic factors, the researchers emphasized. In this study, genetic factors explained about 40 percent of the individual differences in math anxiety.

more at Who’s afraid of math? Study finds some genetic factors — ScienceDaily.

America’s first settlers were trapped in Beringia for 10,000 years

The ancestors of Native Americans came to the New World by walking over a land bridge across the Bering Strait. But there’s a rather glaring 10,000 year gap in the story — one that could be explained by a migratory pause that lasted for millennia.

via America’s first settlers were trapped in Beringia for 10,000 years.

I’ve always thought of the idea of a land bridge as a narrow strip of land.  Apparently it might have been as wide as Alaska and hosted an environment for a culture to have thrived in for thousands of years.  It’ll be interesting to see if they can find any archaeological evidence for this theory.

The importance of (experimental) design — ScienceDaily

One of the hottest debates in evolutionary biology concerns the origin of behavior: is it genetically encoded or do animals and birds copy their parents or other individuals? A classic experiment published in 2000 seemed to provide overwhelming evidence that a particular behavioral choice (whether individuals of a species of swallow breed in a small colony or a large one) is largely genetically determined. Scientists have now re-examined the data and shown that the findings could be explained by random choice.

via The importance of (experimental) design — ScienceDaily.

A shot across the bow for evolutionary psychology?  One of the hardest things about behavioral sciences is sussing out genetic behavior from learned behavior.  This study apparently just added a new wrinkle to take into account when looking at behavior.  It’s about animal behavior, but I suspect there are implications for human studies as well.

It seems like these kinds of studies are getting progressively more expensive.  Human studies now need to be cross cultural to avoid WEIRD (western, educated, industrial, rich, democratic) biases.  Now they’ll have to look out for these identified fallacies.

Seven things about evolution – john hawks weblog

English: This is a recreated vector image in S...
José-Manuel Benitos: “Simplified scheme of human evolution, it does not try to be trustworthy, but a symbol of this process” (Photo credit: Wikipedia)

What is evolution?

In its original sense, evolution meant “unrolling”, as if a papyrus scroll were being unrolled to reveal its contents. We may talk about the “evolution” of many things, from an individual’s lifetime to the evolution of the universe. In the most general sense, evolution means “change”.

Biologists are very specific about the kinds of processes that qualify as “evolution” in the biological sense. Biological evolution is genetic change in a population over time. Populations and individuals change in many ways, but only some changes are evolution.

Here’s a list of seven things about evolution. It’s not comprehensive but it hits on several important issues that help to understand how evolutionary biologists think about the process of evolutionary change.

via Seven things about evolution – john hawks weblog.

John Hawks gives a good primer on some common misconceptions about evolution.  One that I run into a lot among creationists, is that they assume that Darwin’s writings are a sacred scripture of sorts for people who accept evolution.

I’ve done a modest amount of reading on evolution and have never felt the need to read ‘On the Origin of Species’ or ‘Descent of Man’, any more than I’ve ever felt to need to read books on computer programming from the 1950s.  Scientific theories are constantly being improved and reading 19th century versions might be inspiring for some, but usually isn’t required for understanding.

Studies of a skin color gene across global populations reveal shared origins | Penn State University

English: Skin color distribution around the wo...
English: Skin color distribution around the world, data for native populations collected by R. Biasutti prior to 1940 Italiano: Distribuzione del colore della pelle di tutto il mondo, i dati raccolti per le popolazioni native di R. Biasutti prima del 1940 (Photo credit: Wikipedia)

All instances of a gene mutation that contributes to light skin color in Europeans came from the same chromosome of one person who most likely lived at least 10,000 years ago, according to Penn State College of Medicine researchers.

via Studies of a skin color gene across global populations reveal shared origins | Penn State University.

An interesting article on how the genes for light skin tone may have originated.

All the different skin colors are relatively recent developments.  Anatomically modern humans evolved in Africa 200,000 or more years ago, where we were all black.  60,000-90,000 years ago, a small population migrated out of Africa, whose descendants went on the settle the rest of the world.

Your skin tone is most likely a factor of where your ancestors lived over the last 10,000-90,000 years.  Lighter skin tone in higher latitudes and darker in lower latitudes.

Lower latitudes get hit with more direct sunlight, and darker skin is better at protecting against skin cancer, but not as good at vitamin D production.  Higher latitudes get less direct sunlight, and lighter skin is better at vitamin D production.

At least that’s the prevailing theory as I understand it.  I suspect how much of your body is covered in those latitudes, due to variations in temperature, is a factor as well.

But northern European skin is particularly light and susceptible to skin cancer.  I find the idea that it arose from a single person as little as 10,000 years ago fascinating.

David Dobbs mucks up evolution, part II « Why Evolution Is True

David Dobbs mucks up evolution, part II « Why Evolution Is True.

The second part of Jerry Coyne’s response to David Dobb’s Aeon piece on the problems with the selfish gene metaphor.

Be sure to read Dobb’s extended response in the comment section.  Maybe I’m misreading, but Dobb’s appears to be backpedaling significantly from the sentiment expressed in the title of his article.

I find Coyne’s arguments more compelling on this, but I wonder about whether the recent results showing smell memory being passed from generation to generation in mice has any bearing on the debate.