BBCnews is carrying this report on a new DNA research project. By combining the common DNA found in disparate mammal species, scientists have constructed what they think is the DNA sequence of the first mammalian ancestor, a creature that lived about 75 million years ago.

While interesting, such "unionizing" has problems even beyond those mentioned in the article. What they got was not the DNA sequence of our common ancestor, but a sequence which we and that ancestor share. In other words yes, as the article mentions you can find out that the first car had wheels, an engine, and a windshield by looking at modern automobiles. However, surveying a sample of new cars and using them to create an "average" windshield, engine, wheels, etc. will not in fact yield a Model-T*.

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* Yes, yes, I know, I know. The Model-T wasn't the very first "car" as such. However, it's the very first old car most people are familiar with, and besides you can't get two automotive historians to agree on what actually is the first car even if you put them in a sack and tossed them in a river. You should get out more.