Found: Humanity’s Great-Grand-Rat

A new study finds our most distant ancestor — a cool 65 million years back.

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Illustration by Carl Buell

Most of us think we know exactly what we mean when we use the word “mammal”—and most of us are wrong. Typically, we think only of the sub-group of mammals like us, the so-called placental mammals. There are two other kinds, however:  the egg-laying monotremes, which include the duck-billed platypus; and the marsupials, which count kangaroos, opossums and wombats among their ranks. But unless you live in Australia and a few other spots, the vast majority of mammals you run into, even at the zoo, are placentals, a group that encompasses everything from rats to rhinos, gerbils to giraffes, chipmunks to chimps, and, of course humans as well.

It wasn’t always thus, however. Mammals have been around for hundreds of millions of years, but placentals for only tens of millions. Now a new paper just published in Science purports to pinpoint their, or rather, our, origins with impressive specificity. The great-great grandfather of us all, argue the authors, was a small, scurrying, insect-nibbling creature that arose a mere 200,000 to 400,000 years after the cataclysmic extinction event 65 million years ago that wiped out the dinosaurs (or, more precisely, the non-avian dinosaurs, since birds are now considered the one branch of the dinosaur family that survived).

This may seem like just a number to you and me but for paleontologists and evolutionary biologists, it’s something of a bombshell. The prevailing wisdom since the 1990’s, based on assumptions about how quickly mutations arise in DNA, was that the placentals emerged and began to diversify a whopping 35 million earlier, spurred  by the breakup of the giant continent Pangea into the smaller landmasses that exist today. They didn’t really flourish until the dinosaurs went away — but then, who could, with huge, voracious lizards towering overhead?

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There matters stood until five years ago, when a team of scientists began working on trying to understand the evolution of mammals with funding from the National Science Foundation’s “Assembling the Tree of Life” program. Like their predecessors, says co-author Michael Novacek, provost for science and a curator of paleontology at the American Museum of Natural History in New York, “we did use genomics,” or the mammalian gene-line as a sort of bread-crumb-trail that would lead back to our ancestors.

But they also factored in phenomics – analysis of the body structures, biology and even behavior of creatures both living and extinct, looking for points of similarity that suggest how closely two species might be related. “If we have a fossil that falls in between two living species,” says lead author Maureen O’Leary, a vertebrate paleontologist at Stony Brook University, on Long Island, NY, “we use the living species to form the simplest hypothesis for what the fossil’s behavior was like. Things like ‘does it nurse its young, and if so, for how long? Does does it swim, does it eat insects, is it active at night or during the day?’”

All of that information went into a gigantic Web-based database called MorphoBank, in which the scientists recorded more than 4,500 individual traits, both physical and behavioral, culled from 86 placental mammal species, about half of them extinct. “I was working in one cell [of the database],” recalls Novacek, “when another was suddenly populated with information that was being entered in real time by a collaborator from Brazil. It was really exciting.”

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MorphoBank established the species relationships among placental mammals, while DNA and fossil-dating calculations established the timeline — and while that sounds simple enough, it was, says Novacek, “hugely laborious.” Indeed, writes Duke University biologist Anne Yoder in a Science commentary, “O’Leary et al.’s study offers a level of sophistication and meticulous analysis of morphological and paleontological data that is unprecedented.”

All that impressive brainwork led us back to a rather humbling place: You, your loved ones and your  friends, not to mention Abe Lincoln, Winston Churchill, Napoleon, Babe Ruth, Marilyn Monroe—all of us, in other words—are the multi-multi-generational grandkids of a rat-like, half-pound, furry-tailed bug-eater. Like it or not. The work, Novacek promises, will go on. “This thing will continue to grow like an organism. We have this important new result, but we also have a playground for future research.” The science may advance, but our egos may never recover.

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I'm really fighting the urge to make an Intersect joke, but I doubt there are any Chuck fans out there to notice :)

My real question is, how does this system handle conflict? If one group of studies seems to support Hypothesis A, and another group seems to support conflicting Hypothesis B, how does it resolve the difference? (And don't say there aren't any conflicts :-p)


I am not descended from a rat.  


I was looking for 'page 2' that explains the remarkable timing of the species origin right after the KT boundary. This seems to imply some causal relationship. Fascinating, if verifiable.


Now I know....RATS are still walking on earth! most RATS with white neck.


This sounds like an interesting new methodology. It'll be cool to see what else can be determined with the database. 


Its a phenomena that conservatism has never recovered from, after all there is no such thing as evolution in their rat brains!


Can any of you be so kind to explain to me any of the following?.

How they were 70,000 witnesses to the Miracle of the Sun at Fatima, Portugal in 1917?

How the Virgin Mary statue shed tears in Naju,Korea in 1986 or in several other places?

How the tilma at Guadalupe has lasted 200 years?.it normally only lasts 30 yrs

How the eyes of the image at Guadalupe has microscopic images of Juan diego and 13 other people?

How the colors of the painting of the virgin Mary at the las Lajas cave penetrate 3 ft. of rock?

How the bodies of Catholic saints  like Padre Pio and others have lasted 40 yrs or more without corruption?

How the blood of St. Januarius liquefies on his feast day?

How the millions of miracles and healings that have taken place throughout the world for centuries?

How the image of the Shroud of Turin was formed?

How a Eucharistic miracles (in 2001 in Kerala, India) can happen?

Or if you believe in Evolution? any one of these please??please?

Why the best labs in the world cannot create life when evolution believes it happened by chance?

How can a mixture of acids create life with a reproductive mechanism already in place?

Why do whales have lungs and fishes have gills even though they have the same descendant?

Why is it that the earliest human writing occurred only in  3000 B.C? -no record of human writings for millions of years?

Why we are the only planet with life? SETI has searched over 200 trillion km and counting. Heck you have more chances winning the lottery!!

How can frogs, fish and other creatures fall from the sky?How dead fish land up on shores?

Why are humans the only ones who have an ability to develop an argument, follow a line of logic, draw conclusions and frame hypotheses .We have a marked faculty for language, of course, intertwined with our powers of reason.Our vocabulary is enormous,  grammar complex, our conversations deep and meaningful.We have the ability to codify language in writing .<BR>We also have a strong spirit of inquiry and our research in the fields of astronomy, mathematics, medicine and physics is noteworthy.We yearn for meaning in life and devote so much of our time to philosophy, theology and ethics. We not only have questions  of origin but also of destiny. We also have a refined aesthetic sense.Admire beauty and long to surround ourselves with it.We cultivate a garden, puts flowers in a vase, or hang up a painting, in expressing  our love of beauty.

We also have a strong creative impulse as seen in our poetry, painting, dance, drama and music and to a lesser extent our creativity is also evident in the way we gather in weekly craft groups to weave baskets, spin wool, knit shawls, and cover photo albums.Our sense of humour ,Our delight in the ridiculous and our love of a good laugh is plain .<BR>

Reason, language, inquiry, wonder, longing, religion, morality, aesthetics, creativity, imagination, aspiration and humour ... such intangible but fundamental qualities are so unique to us humans and yet you say we are an animal  “evolved” from other species? Which??

The most famous “transitional” fossil is the Archeoptryx.So far 20 have been found but they are all the same.Why?

The bacteria flagellum it is 20 nanometres thick (1 nanometre is one millionth of a millimetre) it has a whip-like tail, called a flagellum, which it spins at approximately 100,000 revolutions per minute.This complex biological motor requires 20 seperate components to be assembled in “perfect” order for the motor to function and the organism to thrive.Since it is absurd to think that one single mutation could have produced this complex mechanism and there would be no biological advantage to a partially constructed one,the bacteria flagellum simply could not have developed through natural selection .So how do you explain that?

If the earth was one degree too close to the sun ,it would have been too hot and one degree farther from the sun,it would have been too cold and yet you say –there is no God?

Please google any of the above for more info

Before you trust anything with your life and eternity.Make sure you have all the answers.Don’t lose your soul to the devil!.He is the prince of lies.

The greatest act of human intelligence is knowing GOD! - Mother Theresa

Only a fool says there is no God – Bible


I can't see how this comes as a surprise to anyone.  That we are descended from rat-like creatures actually explains lawyers, politicians, terrorists and other rat-like individuals among us.