AP Biology class blog for discussing current research in Biology

We used to be shrews!?!

Ever think where did we come from?  Well, one answer to that could be evolution. While it is not yet a proven fact, it is a theory that shows promise to be true.

Experts on the matter of evolution “recorded 4,500 physical traits for 86 mammalian species, including 40 that are now extinct.”  Using this information in tandem with DNA samples, the experts were able to figure out the probable start of placental mammals.  One of the findings was that the rise of placental mammals came after the dinosaurs had become extinct.  This was an earlier hypothesis that was now confirmed. The death of the Dinosaurs would allow for mammals to fill the top of the food chain where the dinosaurs once stood.  Less competition makes it easier to rise to the top.  Dr. Jonathan Bloch, who works at the Florida museum of Natural history, said “This gives us a new perspective of how major change can influence the history of life, like the extinction of the dinosaurs. This was a major event in Earth’s history that potentially then results in setting the framework for the entire ordinal diversification of mammals, including our own very distant ancestors.”

I think this is incredibly cool how all species could be related to one primal and ancient ancestor.  It shows how we are all linked in some way.

What do you guys think on the matter?


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  1. ilikebioha

    I believe this study to hold a lot of truth. In my 12th grade biology class we just learned about Developmental Regulatory Genes. These different genes are in a hierarchy, and the lower down the genes are, the more specific their commands are to a species or specific animal. These genes dictate when another gene will be turned on or where a gene will go. Apparently, all animals have extremely similar genes considering how different we look and act(ex- humans and mice are 85% genetically identical) . The thing that makes us different is the regulatory genes turning on and off and them dictating other regulatory genes what to do. This theory strongly supports the theory of evolution.

    This is a great video that explains Developmental regulatory

  2. dwil

    I think it is very interesting how almost all living things are linked in their genetics. Despite the fact that humans other animals look very different on the outside, there DNA is and actually very, very similar. In fact, humans share 50% of their DNA with a banana. It is amazing what the small differences in our genome can control.

    Here is an article on that fact.

  3. evolucious

    I have to admit – I was unfamiliar with what a shrew was until I searched it up. Did you know that the pigmy shrew is the smallest North American mammal? Furthermore shrews only live 1 to 2 years. Hard to believe that we “used to be shrews”!
    Read more about this animal at:

  4. explodingllama342

    There are actually an incredible amount of misconceptions about evolution. This piece explains five of the most common ones. It’s a shame when people who have little to no information on a topic start making random assertions. It is pretty neat that although evolution is still technically just a theory, many people treat it as a fact. Although, this may be due to misinformation about the difference between a heavily-supported theory and fact.

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