Before Humanity: Denisovans
- erudite .
- Jul 1, 2022
- 2 min read
By Anoushka Ghosh
Before Homo sapiens, human beings were mere neanderthals. Neanderthals are an extinct species of the archaic humans who were once living and breathing 40,000 years ago. Alas, many factors such as inbreeding, small population size, and other factors led to the unfortunate extinction of the subspecies. Yet, it is interesting to understand that there was a similar subspecies of the archaic humans, and these were the Denisovans. Denisovans are a species of hominids that originated from Asia, and the interesting aspects of these unevolved beings were as closely related to neanderthals as possible. So, what is so significant about these hominids?
Denisovans were named after the Denisova Cave in Serbia wherein the first fossil of these beings were found. However, they are largely scarce and have very few remains that were uncovered. Interestingly, these hominids came about due to the species Homo heidelbergensis leaving Africa for Eurasia approximately 700,000 years ago. This then led to the group being split into two groups: western and eastern. This led to the birth of the Neanderthals for the western group, and the Denisovans for the eastern group.
In 2010, scientists found DNA from the pinky bone and tooth which led to the understanding that a group, such as the Denisovans, existed. How does it occur? Well, Liran Carmel from the Hebrew University of Jerusalem led the research team to discover DNA evidence of the Denisovans. DNA is a unique string of chemical letters that have instructions for producing protein. It gives us information of the type of protein that is produced and the activity of the gene. Therefore, it depends on whether or not DNA methylation has occurred which means that a methyl group (-CH3) is added to the DNA molecule. These scientists studied the methylation patterns for ancient humans, and tied the physical features of the Neanderthals to modern humans. This way, it would be easier to discover the physical features of the Denisovans by following the methylation patterns. Yet, this is with the assumption that mutations have not inactivated the gene expression of a particular protein.
Intriguingly, the Denisovans are nothing like modern humans or Neanderthals. “What we’re looking at here is not just another Neanderthal,” says Murray Cox from Massey University. “We’re really looking at a third group that looks quite different from both modern humans and Neanderthals—that’s really interesting.” These species would allegedly have the Xiahe jaw from Tibet that is strongly built, low craniums, low foreheads, and wide pelvises. Yet, these are all features that are observed from the bone fragments and dentures that were found as fossils. Till date, there are large uncertainties in the actual appearance of the Denisovan ancestors as gene expression depends upon mutations that could deactivate or activate genes rendering predictions null and incorrect. The mystery of the Denisovans will remain unsolved.
Sources:
Comments