Previous Year Question
The word ‘Denisovan’ is sometimes mentioned in media in reference to
fossils of a kind of dinosaurs
an early human species
a cave system found in North-East India
a geological period in the history of Indian subcontinent
Correct Answer: B
Detailed Solution
The Denisovans were an extinct group of archaic or early humans, identified primarily through the study of ancient DNA. They were close evolutionary relatives of modern humans and Neanderthals.
Discovery and naming
In 2008, a very small fragment of a human finger bone was discovered in Denisova Cave in southern Siberia.
Scientists at the Max Planck Institute sequenced the ancient DNA recovered from this bone.
Genetic research published in 2010 showed that the DNA belonged neither to a modern human nor to a Neanderthal.
It represented a previously unknown genetic group of archaic humans.
The group was named Denisovans after Denisova Cave.
Position in human evolution
The broad genetic relationship can be understood as follows:
Neanderthals and Denisovans were closely related sister groups.
Both were among the closest extinct relatives of modern humans.
Modern humans interbred with both Neanderthals and Denisovans.
Consequently, traces of Denisovan DNA survive in some present-day human populations.
Denisovan ancestry is highest in certain populations of Papua New Guinea and Oceania, reaching approximately 4-6% in some populations.
Other Denisovan evidence
Initially, Denisovans were known principally from the Siberian finger bone and a few teeth.
In 2019, the Xiahe mandible from Baishiya Karst Cave on the Tibetan Plateau in China was identified as Denisovan through ancient protein analysis.
The mandible is at least 160,000 years old.
It provided the first direct Denisovan fossil evidence outside Denisova Cave.
In 2022, an ancient tooth recovered from Cobra Cave in Laos was also identified as probably Denisovan.
Scientific caution
Option (b) uses the expression “an early human species” and is therefore the correct examination answer. In scientific literature, Denisovans are often described more cautiously as an archaic hominin group, population or lineage, because their precise formal taxonomic status as a separate species remains debated.
Why are the other options incorrect?
Option (a): Denisovans belong to human evolutionary history, not to dinosaurs.
Option (c): Denisova Cave is situated in southern Siberia, not North-East India.
Option (d): Denisovan is not the name of a geological period.