Genes tell who we are

By studying doo-doo, or excrement as it is called, it is, in fact, possible to find out quite a lot about a person. The excrement consists of cells that contain DNA. They also contain remains of DNA from the food people have eaten. For instance, it's possible to tell whether you have eaten popcorn or a banana. This is why a geneticist can study you and your diet by studying faeces, as doo-doo is called in scientific language.

Varied Stone Age diet

Using some sort of magic chemical trick, researchers can recover DNA from dried up doo-doo. DNA is no more mysterious than long sequences of chemical codes that are also called DNA molecules. Researchers compare the DNA codes in ancient excrement with DNA from animals and plants that are alive today. By doing this, they have figured out quite a lot about some people who lived in a cave in Texas several thousand years ago. Finds of human DNA in the excrement revealed that the cave-dwellers belonged to the indigenous people of America. Searches for animal and plant DNA showed that these people ate sunflower seeds, acorns, leaves, legumes, sheep and antelope. They also chewed tobacco. One single lump of doo-doo contained genetic traces of four different animals and three plants. With such a varied diet, they probably knew how to mix different types foods to make a good meal. Norwegian archaeologists dream of making similar genetic tests on Viking excrement found in an ancient toilet in the Viking village of Kaupang. However, the samples are in storage for the time being. Perhaps this might be a job for you in a few years?

ADDITIONAL INFORMATION:

We come from Africa!

By comparing DNA codes, geneticists are trying to understand the relationship between different peoples on the Earth. This job is sort of like the job language researchers do when they try to find out which languages are related to each other. It is not hard to see that Norwegian and Swedish are quite similar and closely related even though some of the letters are different. Chinese and Greek, on the other hand, have little in common with our languages. By comparing the DNA codes of people in Africa, Norway, China and other countries, is it possible to set up relationship trees. It turns out that all the people living on Earth today probably had a common ancestral mother and father who lived in Africa.

DNA detectives

The police often get help from genetic detectives to solve crimes. To help them, researchers use some special codes in the DNA that can be compared with other codes, like looking for certain words in the text of pop tunes. But instead of repeating words like ?baby, baby baby?, they contain repeat sequences of DNA codes like GAGAGAGA. Every person has his or her own personal sequence of these DNA codes. A little bit of DNA from a tiny skin cell or hair cell can therefore be enough to help convict a criminal. DNA can also be used to determine whether people are related to each other, for example, to find out who is the father of a child. The descendants of the famous US president Thomas Jefferson have experienced this first hand. Jefferson lived 200 years ago. At that time, it was legal for white people to own slaves, but it was a great disgrace to have children with them. However, DNA tests of the descendants of the president and one of his slaves, Sally Hemings, show that they had children together. When Jefferson was president, he fought hard against freeing the slaves, and he was very much against black and white people having children together. Talk about being exposed as a hypocrite many years after your death!

DIFFICULT WORDS:

Molecule: The whole world and everything in it are made up of teeny tiny invisible building blocks known as atoms. When two or more atoms join together, they form a molecule. If you think of atoms as Lego blocks, the molecules are all the fun things you can make out of Legos such as cars, trains, boats, houses and people.

DNA and genes: DNA molecules are actually long threads of chemical codes. The DNA codes in your cells contain recipes for all the ingredients needed to make YOU. Altogether, we are talking about roughly 140 000 recipes, and each recipe is called a gene.

Translation: Linda Sivesind

*Published in 'Nysgjerrigper' No. 2, 2001*