What is the difference between DNA and eDNA?

A new study has found that us humans are leaving our DNA everywhere - and scientists think information could be used to learn about disease, solve crimes and even discover archaeological sites!

They have called this eDNA - e standing for 'environment' - the different places that this DNA is found.

By studying people's DNA, we can learn more about what diseases they may risk developing, and learn more about different populations' biological history.

Unsure about what the different words mean? Check out Newsround's guide further down the page.

What is DNA?

DNA stands for deoxyribonucleic acid and carries unique and useful chemical information. If humans were computers DNA would be our coding - it tells us how to grow and function.

DNA instructions sit inside cells and the full set of DNA is called a genome. In humans, the genome consists of 23 pairs of chromosomes located in the cell's nucleus.

How many chromosomes each living thing has can vary a lot. Humans have 46 chromosomes in each cell. The fruit fly has only 8 chromosomes, while red king crabs have a whopping 208!

What is eDNA?

Scientists found eDNA on footprints in the beach

You might be thinking of something electronic because of the 'e' prefix - but it's not that! High quality DNA found in environments where humans have been - the beach, a hospital or even air - is known as eDNA.

Normal DNA samples can be extracted and studied in a lab to discover someone's heritage. You might have heard of this before through things like ancestry tests, where people send a lab a sample of their spit to find out more about their biological family's past.

Human DNA in the spit sample is analysed and scientists can work out where it came from.

With eDNA, scientists can look at DNA in certain places to find out genetic history and ancestry of people nearby. Researchers looked at samples taken from different environments in the US and Ireland, and found high quality DNA with plenty of information to look at in the lab.

Why did the scientists do the study?

The researchers say eDNA can be used for many different things. Some of these include helping with criminal forensics or discovering archaeological sites, for example by finding human DNA in an area and exploring where it came from.

Scientists even think they can use eDNA for disease prevention, by looking at what genetic mutations there are in certain areas. A genetic mutation is a change in a piece of DNA - it can happen naturally, be passed on through generations, or caused by things like cigarette smoke and radiation.

One of the professors in the study said he had concerns around how eDNA could be used - such as to track people from the DNA in their environment - and said that some safety checks should be put in place amongst scientists to make sure people's privacy is protected.