The Genome of a Human Recovered from a cup of mud

[janterry]

No skeleton needed - just 'environmental DNA' to determine her sex and when she lived.

From the article:
A cup of mud that has been buried beneath the floor of a cave for millennia has just yielded up the genome of an ancient human.

Analysis reveals traces of a woman who lived 25,000 years ago, during the last ice age; and, although we don't know much about her, she represents a significant scientific achievement: the feasibility of identifying ancient human populations even when there are no bones to recover.

and

Only a tiny fraction of her genome was recovered, but from that, the researchers were able to infer that she was a member of a previously unknown group of modern humans. That group is now extinct, but it contributed to present day populations in Europe and Asia, as discovered when the ancient genome was compared to current human genomes.

and

"Genome-wide ancient sediment DNA might open new directions for the study of whole ecosystems, including interactions between different species and aspects of human practices linked to the use of animals or plants."

https://www.sciencealert.com/a-human-genome-has-been-recovered-from-cave-dirt

[marble falls]

1. Whether one takes something or not, they will leave something.

[csziggy]

3. In forensic science this is known as Locard's Exchange Principle

Like Hans Gross and Alphonse Bertillon before him, (Edmond) Locard advocated the application of scientific methods and logic to criminal investigation and identification . Locard's work formed the basis for what is widely regarded as a cornerstone of the forensic sciences, Locard's Exchange Principle, which states that with contact between two items, there will be an exchange. It was Locard's assertion that when any person comes into contact with an object or another person, a cross-transfer of physical evidence occurs. By recognizing, documenting, and examining the nature and extent of this evidentiary exchange, Locard observed that criminals could be associated with particular locations, items of evidence , and victims. The detection of the exchanged materials is interpreted to mean that the two objects were in contact. This is the cause and effect principle reversed; the effect is observed and the cause is concluded.

Crime reconstruction involves examining the available physical evidence, those materials left at or removed from the scene, victim, or offender, for example hairs, fibers , and soil, as well as fingerprints, footprints, genetic markers (DNA ), or handwriting. These forensically established contacts are then considered in light of available and reliable witness, the victim, and a suspect's statements. From this, theories regarding the circumstances of the crime can be generated and falsified by logically applying the information of the established facts of the case.

Locard's publications make no mention of an "exchange principle," although he did make the observation "Il est impossible au malfaiteur d'agir avec l'intensité que suppose l'action criminelle sans laisser des traces de son passage." (It is impossible for a criminal to act, especially considering the intensity of a crime, without leaving traces of this presence.). The term "principle of exchange" first appears in Police and Crime-Detection, in 1940, and was adapted from Locard's observations.

https://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/locards-exchange-principle

[Javaman]

2. what truly amazes me about these discoveries is...

(and this is probably a pretty dumb question)

how do the scientists know to look in these particular caves?