Blog Archives

Madagascar Again! And Again!

Following Human Migrations

Analysis of human DNA has allowed researchers to refine theories about early human migrations such as the “Out of Africa” theory and how humans eventually got to North and South America.

A map shows human migration routes beginning about 100,000 years ago, based on mitochondrial (yellow) and Y-chromosome (blue) DNA evidence collected by the National Geographic Society's Genographic Project and other sources.

Some very well known examples of this type of genomic and mitochondrial DNA work are summarized in the excellent books Journey of Man and Deep Ancestry by Spencer Wells and The Seven Daughters of Eve  and Saxons, Vikings, & Celts by Bryan Sykes.

This type of genetic research is the obvious way to obtain information on human migrations. Yes, I’m implying there is another (less obvious?) way to gather information.

Of mice . . .

Norwegian Mouse, image courtesy George Shuklin

Researchers can use the “companions” we bring along with us when we move. A recent study about mice (Fellow Travelers) is “in press” at the moment at the BioMed Central (BMC) Evolutionary Biology journal. The researchers have documented that mice in Greenland are descended from mice in Norway. The Greenland mice must have come from Norwegian forebears that stowed away on the journey to Greenland. Very nice additional evidence to support the timeline of Viking wanderings.

. . . and lice

Body louse, Pediculus humanus var. corporis. Image courtesy of Scott Camazine

Dr. David Reed has learned about humans by using one of our very close companions. Dr. Reed studies ectoparasites, and has done considerable genomic work in lice. By studying lice, he found that body lice diverged from head lice about 170,000 years ago. Body lice require clothing to hide in. Therefore, according to Reed and his coworkers, clothing must have appeared on humans about 170,000 years ago. In his 2011 paper Reed says

A suite of complex behaviors and technologies associated with the transition of archaic to modern Homo sapiens, including improved clothing, are credited with facilitating the successful expansion of AMH [anatomically modern humans] out of Africa into higher latitudes.

Visit your ancestors

The Smithsonian Natural History Museum has finished a great looking exhibit “The Hall of Human Origins“. From online, it looks like it has the latest info on our human family tree along with some spectacular artwork and sculptures to bring it to life.

Depiction of early humans building a shelter. Image courtesy of Karen Carr Studio.

This is on my list of things to see this summer. I know, I have a big “G” on my forehead. As a good friend of my husband’s once shouted (while standing in a parking lot holding a big-ass trophy we had won at a Star Trek convention), “We may be geeks, but we’re the best geeks!”

I plan to post a review of my trip and let you all know how much fun we had.

Tree of life has more leaves than expected

It turns out being a descendent isn’t as clear cut as it seems. As sequences of genomes fill the digital world, their analyses surprise many evolutionary biologists. It is hard to define exactly what a species is. Where do you draw the line between species? Wolves and dogs are clearly different. What about wolves and coyotes? Wolves and huskies? Coyotes and dogs? Labs and Newfies? Mutts and purebreds?

We have a habit of standing where we are and looking back in increments. How else can we learn about our world? Well, scientifically, we are growing up very fast, and need new perspectives. Just because the only information we have is that of clear, distinct species in a neat branching tree doesn’t mean that act of speciation is a neat business. In fact, I’m willing bet the farm that as we study genomes, we will find speciation is messy and “blurry” and species can only be distinctly identified long after the “speciation event”.

If there is even a single event. In some cases there may be a single change that allowed a new species to survive and the old to become extinct. I suspect that for many species (most?) it’s a continuum and that once you get far enough along the continuum, the species are then very distinct. Kind of like the visible spectrum. What’s the difference between 695nm and 700nm? Both are still red light. Once you get to 600nm, however, the light is very clearly orange. Can’t confuse those two colors. I think speciation is likely to the same way. At the very least, different species have interbred in the distant past, making the creation of family trees a bit more challenging.

Here are few stories about finding the “blurriness” in species by comparing genome sequences.

Why is “Extraterrestrials!” always the answer?

Because “Nature abhors a vacuum”. This is an old Latin proverb that can be first attributed to François Rabelais (c. 1494-1553) . Our minds can’t stand unanswered questions. So we populate the emptiness with answers like “Exterrestrials!”. Like the old maps of the world – men couldn’t leave the unknown parts empty and added “Here there be monsters!” or actually drew a few.

What has this got to do with biology? I could wave my hands and say of course behavior is driven by biology. Said and done. Moving on, I must confess, there is no direct link. I was  happily reading science news online and came across the headline:

Man looking for missing cat stumbles on buried ‘UFO’

Of course I was sucked in. I always am. I find it fascinating that the first explanation is always aliens. Even when there is clearly an obvious, logical explanation. There was in this case as well, but you can read the article for yourself if you’re interested.

I just don’t get it.

“When Fruit Flies Strike Out, They Like To Booze It Up”

NPR’s Scott Hensley reporting on brain biochemistry and alcohol. That’s all I have to say. Scott can be very humorous, and this report lends itself well to his humor. No spoilers here. Go read his work.

Drosophila melanogoster - fruit fly

If it’s not Madagasacar, it’s the Galapagos!

What are these things? Icicles? Stalactites? Here’s a hint: chomp!

Shark species identified: Bythaelurus giddingsi

It’s been around a long time, but us humans have just gotten around to seeing it. Shark species are becoming extinct worldwide, and one expert estimates that of the species present ~50 years ago, 90% have become extinct. Since it is now clear there are species out there we’ve never encountered, there are probably even more species becoming extinct than what we are aware of. Ignorance is bliss? No, more like extinction.

A close-up of the shark's pointy teeth. The species has a wide mouth good for grabbing passing fish and invertebrates. The research is published in the March 5 issue of the journal Zootaxa. Photo by Douglas Long

“Icy Finger of Death” posted by Phil Plait on Bad Atronomy

3, 2, 1 Lift Off!

Today is the grand opening of my blog. I’m the last one to jump on the band wagon. Why now? I’ve actually found something useful for a blog. My plan is to use this to post fun bio stuff I come across for my college students and add comments and my opinions. That means it will be most active during the school year and rather sleepy during the summer.