Findings I like, this month

These bits of research failed to make headlines, but you might enjoy them, as I did (disclaimer: I didn’t look into the quality of any of these studies):

  • “Parents Influence on Children’s Eating Habits is Small.” Really?  How could that be?  Apparently, the community, peers, television viewing, and the “food environment” are more important.   I don’t think they were able to separate out young children from teenagers, for this study from Johns Hopkins University.  It claims to be the first-ever study to look at parental influence on eating habits.  (The news release is here.)
  • Autism Medication is Ineffective for Repetitive Behaviors. This is from Seattle Children’s Hospital.  They compared a common anti-depressant (citalopram) that is used to control repetitive behavior in children with autism against a placebo, and found no benefit.  The children wring their hands, or rock back and forth.  The drug was prescribed because some clinician thought that there was a common problem with the brain chemical serotonin.  (The news release is here. )
  • A New Material to Use Inside the Body — Blending Crustaceans and Polyester. Some University of Washington researchers are bio-engineering a substance that can blend two important qualities, stickiness and sturdiness.  You want a severed nerve to be able to grow back in the right direction, so you need some scaffolding that it can grab onto, like a wisteria in your garden.  And you need something that won’t dissolve too easily inside the body. This is an interesting blend, of shells and polyester.  They claim it has prospects for muscle and tendon repairs, too. (The news release is here.)

Chitosan and polyester fibers, at the nano scale.

Chitosan and polyester fibers, at the nano scale. (UW)

  • A Faustian Bargain, for Our Brains? This theory — and it’s more like a hunch — says our evolutionary history is a two-sided coin.  In exchange for evolving bigger, intelligent brains, we may have also been cursed with cancer.  Apparently, humans are more cancer-prone than other primates, and it may be related to a gene that kills off potentially bad cells.  By being more lax, our bodies are able to grow bigger brains.   (The news release is here.)

A manly march out of Africa

I like to imagine what life might have been like for our ancestors.  You can do this with any time period — going back to your great-grandparents, or a few centuries before that, or way back in evolutionary time.  In today’s case, how about 60,000 years ago?

That’s the era when Homo Sapiens were migrating from the Africa to the Middle East, and spreading from there to populate Asia, Europe, Australia and the Americas.  These people were anatomically the same as us.  And it’s surprising how much anthropologists have been able to deduce about them:  They were hunter-gatherers, and probably their lives were similar to hunter-gatherer communities that persisted into the 20th century.

And now there’s evidence that the bands of migrating humans, who probably worked their away across what we now call Egypt and the Sinai, included more men than women.  Alon Keinan of Harvard Medical School, and colleagues, used genetic markers to detect a surprising anomaly in human DNA that must have been triggered about 60,000 years ago.

They compared the genomes of modern people of West African descent with people of European and Asian descent.  The non-Africans show a series of random changes in their X chromosomes, known as “genetic drift,” which only seems to make sense if non-Africans all descended from a group where men outnumbered women.

(I’m skipping over the scientific methods for making these calculations, but it’s worth noting that this type of analysis is possible only using the tools developed for the Human Genome Project.)

We may never be able to say with confidence why those bands of people left.  A writer at New Scientist speculates that warfare might have played a role — that the migrants might have been similar to marauding Vikings.  Or, at the least, they may have been like more recent examples where male explorers and settlers went first (and women were in short supply).

This doesn’t imply that gender relationships back then were structured in any specific way.  But, it’s fair to imagine a charismatic leader, a visionary, whose name we’ll never know, who led early exploring parties up the Nile River, and out of Africa — 60,000 or more years ago.  The first “age of exploration”?

The study was published this month in Nature Genetics.

Spicy microbes

Ecology is full of surprises. And often those surprises have to do with microbes. I’ll write more about microbes in the coming months. I was lucky this week to be able to write about chili peppers and the strange ecology that allowed them to evolve spiciness.

Short version: Josh Tewksbury at the University of Washington, and a team of researchers, found that the spicy substance inside peppers acts as a defense against a fungus. That fungus destroys the seeds inside the peppers. (It turns them black and generally very gross looking.) In climate zones where the fungus grows more readily, the peppers evolved to be spicier. Specifically, they produce more capsaicin. The same chili species in drier zones is not spicy at all.

But what makes it not just interesting, but fascinating, is the three-way relationship between the chili plant, the fungus and a tiny insect. Without all three, the world would be full of bland food.

The insects, as Tewksbury describes them, have mouths shaped like drill bits. They drill into the chili fruit and into the seeds, and eat the nutritious inside of the seeds. They can do a lot of damage, but they don’t destroy all the seeds. However, the holes they drill allow the fungus to get inside the waxy fruit surface and seed surface. By secreting a spicy substance around the seeds, the plant keeps the fungus at bay, just enough to keep the fruit and seeds looking healthy.

As long as the chili peppers look tasty, birds will eat them, as birds are not sensitive to spiciness. And birds are the main distributors of chili pepper seeds.

If you take any of the creatures out of the system, you don’t get spicy habaneros or jalapenos or any of the other peppers we know and love. In fact, all spicy peppers, along with sweet peppers, evolved in the dry forests of Bolivia, Argentina and Paraguay. People bred many varieties from just a few core species. They spread around the world, including to India and Thailand, only post-Columbus.