GUY RAZ, host:
Scientists may have come a step closer to understanding the process of human evolution. A research team from the University of Leicester in Britain found that when fish die, they don't decompose in a random order. In fact, it's the most complex or evolved parts that go first.
And Dr. Rob Sansom, who led the study, says, it could change the way we read and understand the fossil record.
Dr. ROB SANSOM (Researcher, University of Leicester): At this part of the fossil record, we don't have any bones or teeth. So the fossils are very hard to interpret, and decay can play a very important part in fossilization. And through these experiments, we found that decay and decomposition can have a pattern, an effect upon the way we interpret those fossils.
RAZ: What are some of the things that decay first?
Dr. SANSOM: So for an example, some of the things that decay first might be parts of the mouth or parts of the tentacles or sensory equipment like eyes, and it just so happens that those parts of the body would be the most useful in diagnosing and interpreting a fossil.
RAZ: They'd be the most useful because they're the most evolved parts of the body.
Dr.�SANSOM: Yes, the most evolved or the most complex. So you can end up with an organism, or a fossil, that may look more primitive than it may have been in life.
RAZ: So is it possible that a fossil that has been studied has been thought of as a certain species but in fact may have been another one?
Dr.�SANSOM: That is true, yeah. But through the new information that we now have, we now have a framework of data with which to interpret these fossils and place them more correctly in the tree of life. These are experiments to try and understand our earliest ancestors. These fishy fossils are our great, great, great grandfathers of evolution happening there at 500 million years ago.
RAZ: So how did you carry out this study? I mean, you didn't actually go to the ocean searching for these fossils, right?
Dr.�SANSOM: Well, pretty much, yes, actually. The we collected the specimens in the wild, living specimens, and we brought them back and investigated the circumstances of their decomposition from day zero through to 200 days.
RAZ: So you actually had rotting fish in your laboratory?
Dr.�SANSOM: Yeah, our laboratory is not a very popular place to be in the department. There are a series of rotting-fish experiments going on, and the smell can be quite pungent.
RAZ: And so how did you cope with the smell?
Dr.�SANSOM: Oh, I've grown used to that smell for now, but colleagues and visitors to the laboratory are less keen.
RAZ: Dr.�Rob Sansom is a researcher at the University of Leicester in Britain. You can see some of the photographs of his research subjects at our Web site, npr.org.
Dr.�Sansom, thanks so much for joining us.
Dr.�SANSOM: Thank you very much.