Researchers may be able to recover molecular traces in fossils of extinct species. These studies of new ways to explore these traces aim to expand our knowledge of the past of life on Earth, since DNA is very fragile. Researchers have identified that this can be achieved through proteins, which have greater longevity. What can we expect from this discovery? Learn all the details.
Evolutionary connections in fossils revealed by ancient proteins
Scientists in recent years have made progress in finding ancient DNA in fossils, gaining insight into organisms that lived long ago. But the oldest DNA obtained so far dates back about two million years. Proteins, a cell’s molecular machinery, also offer valuable information and have the virtue of surviving much longer, as new research shows.
Scientists have now extracted and sequenced proteins from dental fossils of extinct rhinoceroses, elephants and hippopotamuses, including from a rhino tooth 21-24 million years old. Separate research teams found protein fragments in fossils from vastly different environments – the frigid High Arctic of Canada and a scorching rift valley in Kenya.
“Together, these complementary projects demonstrate that proteins – fundamental building blocks of living organisms that preserve information about evolutionary history – can be found in ancient fossils the world over,” said Harvard University evolutionary biologist Daniel Green, lead author of the Kenya fossils study published in the journal Nature. This opens a new frontier for probing the deep evolutionary past, including the human lineage and perhaps even dinosaurs.
“Ancient proteins can tell us about an organism’s evolutionary history by providing molecular data from specimens too old for DNA preservation. This allows researchers to clarify evolutionary relationships across the tree of life, even for species that went extinct millions of years ago,” said Ryan Sinclair Paterson, a postdoctoral researcher at the University of Copenhagen’s Globe Institute and lead author of the Canada fossil study in Nature.
New discoveries expand frontiers
The ability and feasibility of recovering proteins, even from ancient fossils and under extreme environmental conditions, reinforces the precision of the techniques applied and points to even greater potential for future research. This is relevant when considering situations in which DNA cannot survive, opening up new possibilities.
DNA and proteins are fragile and degrade over time, but proteins are more resilient. The oldest-known DNA is from organisms that lived in Greenland two million years ago. Until now, the oldest-known proteins preserved well enough to offer insight on evolutionary relationships were about four million years old, from the Canadian Arctic. The new research pushes the boundaries of ancient protein research, a field called paleoproteomics, back by millions of years.
Proteins were obtained from teeth of five rhino, elephant and hippo species that lived 1.5–18 million years ago in Kenya’s Turkana region. The proteins showed the ties between the ancient animals and their modern-day relatives. Proteins also were extracted from a fragment of a tooth of an extinct rhino unearthed at a site called Haughton Crater in Nunavut, Canada’s northernmost territory, that was up to 24 million years old. They showed how this species fit into the rhino family tree.
Proteins have allowed us to identify specific biochemical characteristics of the animals in these fossils, such as environmental adaptations, dietary habits, and evolutionary relationships. Proteins become a reliable source of molecular information in paleontological contexts and consolidate this field as a very promising one.
Fossil research beyond DNA
Advances in fossil studies, thanks to the recent extraction of proteins, mark a new era in the search for information about the past, expanding research beyond the use of DNA. It becomes an important tool for modern science, with the potential to decipher the oldest mysteries of life on Earth.