Meet your distant relative, Entelognathus primordialis, possibly the first earthling with a face. Or at least a familiar face.

Entelognathus primordialis (where Entelognathus means “complete jaw”) is described this week in Nature. Discovered in a quarry in China, the remarkably well-preserved fossil is somewhat 3D, displaying a modern type of jaw.

E. primordialis is a placoderm, an early class of fish that lived 430 to 360 million years ago. These fish were covered with an armor of bony plates and gave rise to two later groups—bony fish and cartilaginous fish.

The evolution of jaws is one of the key episodes in the evolution of vertebrates, but the gap between jawed and jawless vertebrates is so large that it has been hard to work out the individual evolutionary steps in the transition. Min Zhu and his colleagues hope to make the link with E. primordialis.

The 419 million-year-old fish fossil has jawbone features previously restricted to bony fishes, but has the full body armor seen in placoderms. It would have been around 20 centimeters (eight inches) long.

Prior to this recent find, most scientists agreed that placoderms had no jaw and were more similar to the cartilaginous fish, like modern day sharks, while the bony fishes are believed to be our ancestors. According to Nature News:

Such fishes went on to dominate the seas and ultimately gave rise to land vertebrates.

In addition to facing off with placoderms, the new study puts cartilaginous fishes into a whole new light—perhaps they are even more evolved than previously thought.

Environmental Groups Need Reform

An independent review panel reported to the United Nations early this week that the Intergovernmental Panel on Climate Change (IPCC) should be fundamentally reformed. According to ScienceInsider, the review gave the IPCC

a solid B+ for its two decades of assessments of the global climate system. But the panel assembled by the InterAcademy Council, which is made up of science academies from around the world, says that there are plenty of areas in which IPCC could do better. Its 113-page report, issued today, calls for a new leadership structure with shorter terms, tighter review procedures, and better lines of communication.

The IPCC shared the Nobel Peace prize with Al Gore in 2007, but errors in a report that year, per the New York Times,

threatened to overshadow the United Nations’ message that climate change is a significant threat requiring urgent collective action.

Another organization formed to protect the environment, in this case marine fisheries, came under attack this week in the journal Nature. You’ll need a subscription to read the article, but the New York Times has a great summary of how the Marine Stewardship Council is “giving its stamp of approval to industrial fisheries that some scientists say are anything but environmentally sustainable.”

Evolutionary Teamwork

There were two recent stories in the news about creature self-sacrifice and evolution.

The first to break was about the idea of kin selection—wherein certain species have sterile members who take one for their relations, such as ants and bees whose workers do everything for the queen’s offspring and have none of their own. Last week scientists, including the venerable E.O. Wilson, disputed the idea of kin selection in the journal Nature. This week, two articles in the New York Times and Science News had scientists taking sides and putting on their boxing gloves over this. Controversies keep science fun and interesting!

“Charitable” might not be the first word that comes to mind when you think of E. coli bacteria, but the second story describes how charitable bacteria share with others to become resistant to antibacterial agents. Studying E. coli, scientists found that “just a few drug-resistant bacteria can release a protective substance that makes a whole population resilient to drugs.” [Science News]  The protective substance is a molecule called indole, which is known to help E. coli handle stress. And as Ed Yong reports in Discover, even though it takes the E. coli a lot of energy to produce indole,

Having multiplied from common ancestors, the bacteria in the group are all related to one another and carry virtually the same genes. In this light, making a small sacrifice for the sake of genetically identical others is a good move.

I wonder where that puts them in the kin selection argument?

Sour Babies

This one is purely for fun but does relate to a Science in Action video we produced a while ago describing how facial expressions are innate and not learned. Scientists studying babies’ faces found that babies make the same expressions whether they are tasting something sour, sweet, salty, or bitter for the first time. This video of babies tasting lemons and limes on YouTube will probably make you laugh—and perhaps give you some observational data to judge whether the babies’ reactions seem innate or learned.  Or it might inspire you to perform the innocent experiment on a baby you know…

What did you find fun in science news this week? Share with us!

Baby image by Chris Denbow

Two research articles published online yesterday in Nature publications follow mice research in two behavioral directions—one in father-child bonding and one on exhibiting pain—that may help humans in the future.

Neuroscientists in Calgary found that male mice that were allowed to nuzzle with their infant offspring were able to recognize those offspring as adults. According to Science Now, “That recognition correlates with new neuron growth in dad’s brain, the team reports online today in Nature Neuroscience. When Mak and Weiss injected a marker that tags newly formed neurons into the fathers just after their pups were born, they found up to 40% more new neurons in… mice that had nuzzled their pups.

“The results suggest that in mice, and perhaps in humans, young babies and dads bond biologically in ways that can last a lifetime.”

Other scientists in Canada studied facial expressions in mice, looking for signs of pain. They discovered that when subjected to moderate pain stimuli, mice showed discomfort through facial expressions in the same way humans do. (Watch Science in Action’s story about human facial expressions here.)

Their study, published online May 9 in the journal Nature Methods, also details the development of a Mouse Grimace Scale that could inform better treatments for humans and improve conditions for lab animals.

Continuing experiments in the lab will investigate whether the scale works equally well in other species, whether drugs given to mice after surgical procedures work well at their commonly prescribed doses, and whether mice can respond to the facial pain cues of other mice.

Creative Commons image by George Shuklin