Investigating Relationships

Introduction


DNA Gel In some ways, collecting evidence is the easy part of science. Much trickier are evaluating the data, figuring out how one piece of information relates to another, and deciding what it all means.

In recent years, for example, advances in genetics have allowed us to tackle questions that once seemed impossible to answer. Where and when did humans originate? Why can only humans speak?

The pattern of black and white lines on the electrophoresis gel shown here holds some of the answers. Electrophoresis is a technique that allows us to record and compare patterns of genetic material found in the DNA of every living thing. This particular gel is very special: It reveals the genetic makeup of a Neanderthal who lived 38,000 years ago. With it, we can see changes over time in some of the traits that make us human.

But genetic evidence isn’t as black and white as the lines on a gel. Reams of genetic data don’t always supply an easy answer to the most obvious question: How do differences in genes translate into the physical and behavioral differences that make us human?