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News stories tagged with "evolution"

How humans inhale and exhale. Clip art: <a href="http://www.clipart.dk.co.uk/457/subject/Biology/Breathing">DK Images</a>
How humans inhale and exhale. Clip art: DK Images

Natural Selections: the evolution of breathing

All creatures breathe in some fashion, but how the job gets done has changed from fish to amphibian to reptile to mammal. Curt Stager and Martha Foley chart the evolution of animal respiration.  Go to full article
Lionesses love the mane. . . Photo: <a href="http://www.flickr.com/photos/digitalart/3240381175/">Art G</a>, Creative Commons, some rights reserved
Lionesses love the mane. . . Photo: Art G, Creative Commons, some rights reserved

Natural Selections: Lion Manes

Why would a heavy fur cape, like a lion's mane, be appropriate on a tropical savanna?

As with male fashion in humans, it appears the that the lionesses of the Serengeti like it--the thicker and darker, the better. Martha Foley and Dr. Curt Stager talk hair.  Go to full article
Top: Reconstruction of <em>Ambulocetus natans</em>, a primitive cetacean from 40-50 million years ago, by <a href="http://spinops.blogspot.com">Nobu Tamura</a>, CC <a href="http://en.wikipedia.org/wiki/en:GNU_Free_Documentation_License">some rights reserved</a>, and Bottom: Reconstruction of <em>Kutchicetus</em>, another ancestor of today's sea mammals.
Top: Reconstruction of Ambulocetus natans, a primitive cetacean from 40-50 million years ago, by Nobu Tamura, CC some rights reserved, and Bottom: Reconstruction of Kutchicetus, another ancestor of today's sea mammals.

Natural Selections: Whales and land mammals

Whales are relatively new to the ocean. Fossil evidence allows evolutionary biologists to trace the whale's transformation from land mammal into air-breathing ocean dweller. Today's whales still carry a legacy of their landed past in a vestigial pelvis, femur, and other typical anatomical traits. Martha Foley and Dr. Curt Stager dig into a big topic.  Go to full article
Sickle cells in the blood (foreground) result from two inherited copies of the gene, and cause anemia. One copy confers resistance to malaria. Photo: <a href="http://www.flickr.com/photos/wellcomeimages/">Wellcome Images</a>, CC <a href="http://creativecommons.org/licenses/by-nc-nd/2.0/">some rights reserved</a>
Sickle cells in the blood (foreground) result from two inherited copies of the gene, and cause anemia. One copy confers resistance to malaria. Photo: Wellcome Images, CC some rights reserved

Natural Selections: When evolution GOES WRONG!

Not all evolutionary change is good. Genetic changes can be neutral or harmful, as well as beneficial. And some change can be both, conferring benefit when a single copy of a gene is present, and causing a life-threatening disease when copies are inherited from both parents. Martha Foley and Dr. Curt Stager roll the dice on evolution.  Go to full article
Whales retain a vestigal pelvis and femur disconnected from the spine--a remnant of their time on land.
Whales retain a vestigal pelvis and femur disconnected from the spine--a remnant of their time on land.

Natural Selections: Convergent Evolution

We think of evolution as moving in a linear progression from the sea to the land. But some creatures, such as whales and dolphins, clearly adapted to the land, then returned to the sea. Dr. Curt Stager and Martha Foley talk about convergent evolution.  Go to full article
"If the DNA has been changed somehow--that would be a mutant." --Curt Stager
"If the DNA has been changed somehow--that would be a mutant." --Curt Stager

Natural Selections: Mutants

Mutants are neither the creepy brain domes of science fiction, nor the smart-mouth turtles of the cartoons. Mutations arise all the time from environmental exposure to mutagenic substances and from imperfections in cellular reproduction. Martha Foley and Dr. Curt Stager talk change--genetic change.  Go to full article

Natural Selections: What makes a new species?

What draws the line between one species and another? New species are said to diverge when mutations occur that make it impossible to interbreed. Sometimes it's not much -- case in point: humans and chimpanzees. Curt Stager tells Martha Foley the key difference came when two short chromosomes in the chimp joined to form one long chromosome in humans.  Go to full article
Hummingbird and whippoorwill
Hummingbird and whippoorwill

Natural Selections: the evolution of birds

Martha Foley and Dr. Curt Stager study the evolution of birds and discover that some unlikely species are very closely related.  Go to full article

Natural Selections: Ghosts of Evolution

Dr. Curt Stager and Martha Foley discuss plants that have outlived the animals they co-evolved with.  Go to full article

Natural Selections: Whale anatomy

From the bones of their fins to the free-floating and functionless pelvis, the bodies of cetaceans show clear signs of having once lived on land. Why go back to the sea? Dr Curt Stager and Martha Foley examine the tale of the whale.  Go to full article

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