Scientists Analyze the Inner Ear of Different Neanderthals and Detect When Exactly the ‘Bottleneck’ Event Happened
Past examinations have revealed how Neanderthals faced a massive collapse at one point in time. This collapse supposedly had an impact on the genetic diversity of this group, making the last generations of these prehistoric humans exhibit uniform traits, stated IFL Science. A team of researchers has possibly resolved this problem and published their results in the journal Nature Communications.
As per the study, the collapse happened around 110,000 years ago. This assertion was made based on the examination of the 'bony labyrinth' present in the inner ear of different Neanderthal populations. Researchers compared the features of the labyrinth in the pre-Neanderthal specimens, early Neanderthals, and classic Neanderthals, in order to understand where exactly diversity slowed down. This helped them to pinpoint when exactly the collapse happened, as the event correlated with the reversal of genetic variance.
The fossils examined in the study came from Atapuerca (Spain) and Krapina (Croatia), as well as several locations all over Europe and western Asia, stated SciTech Daily. Experts specifically focused on the inner ear structure because these parts are known to be created mostly by genes. Outside factors do not impact the formation much because these parts are fully in place at the time of birth. “This makes variation in the semicircular canals an ideal proxy for studying evolutionary relationships between species in the past, since any differences between fossil specimens reflect underlying genetic differences. The present study represents a novel approach to estimating genetic diversity within Neandertal populations,” Binghamton University Professor of Anthropology Rolf Quam shared.
Atapuerca fossils were dated back to around 400,000 years ago and hence were considered to be Neanderthal ancestors known as pre-Neanderthal. Samples from the Croatian site of Krapina were adjudged to be early Neanderthals as they were 130,000 years old. For the study, researchers had in their custody several samples of classic Neanderthals, which were of different ages as well as places. Classic Neanderthals came into existence around 70,000 years ago and went extinct 40,000 years ago. The comparison detected genetic loss between early Neanderthals and classic Neanderthals. Analysis suggested that genetic variation slowed down around 110,000 years ago, as the prehistoric humans were moving from 'early' to 'classic.'
Researchers made sure to include a variety of locations in their examination, so that their results are comprehensive and not limited. The results challenge the past assertion that this 'bottleneck' event occurred when the early Neanderthals came into being. The finding even stunned experts. "We were surprised to find that the pre-Neanderthals from the Sima de los Huesos exhibited a level of morphological diversity similar to that of the early Neanderthals from Krapina," Alessandro Urciuoli, lead author of the study, shared.
Experts are yet to understand what exactly caused this 'bottleneck' event, according to Live Science. As per experts, such events can be brought on by catastrophic events like climate change, genocide, hunting, and a multitude of other processes capable of reducing the numbers in a very short duration. Further analysis could possibly shed some light on this mystery.