A recent study suggests that Neanderthals experienced a population crash 110,000 years ago, possibly contributing to their eventual extinction. Conducted by an international team of researchers, including scientists from Binghamton University, the study analyzed ancient fossils to track evolutionary changes in these early humans.
The research focused on fossils from Atapuerca in Spain, Krapina in Croatia, and other sites across Europe and Western Asia.
Researchers examined the semicircular canals in the inner ear, which assist with balance. These structures are genetically controlled and remain unchanged from birth, making them useful for studying evolutionary relationships.
“The development of the inner ear structures is known to be under very tight genetic control, since they are fully formed at the time of birth,” said Rolf Quam, one of the study’s lead authors.
“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.”
Fossils from Atapuerca and Krapina
The fossils from Atapuerca, dating back 400,000 years, are considered early ancestors of Neanderthals. Neanderthals later emerged around 250,000 years ago, spreading across Eurasia until their extinction about 40,000 years ago. The Krapina site, dating back approximately 130,000 years, holds one of the most complete collections of early Neanderthal remains.
By comparing the inner ear structures of these fossils with those of later Neanderthals, researchers found that classic Neanderthals had significantly less variation. This supports previous findings from ancient DNA studies, which indicate a genetic bottleneck—a sharp decline in diversity due to a shrinking population.
“New study reveals Neanderthals experienced population crash 110,000 years ago”
was that the ascension of homo sapiens https://t.co/czRVWw20fm pic.twitter.com/rHRc4wdRxl
— cfMC FEROX (@cfmceroz1) February 26, 2025
Ancient DNA analysis suggests that this decline in genetic diversity occurred around 110,000 years ago, affecting later Neanderthal populations. A reduction in population size likely caused this loss, limiting genetic variation and making Neanderthals more vulnerable to environmental changes.
“The reduction in diversity observed between the Krapina sample and classic Neanderthals is especially striking and clear, providing strong evidence of a bottleneck event,” said Mercedes Conde-Valverde, a researcher from the Universidad de Alcalá and co-author of the study.
Challenging long-held assumptions
The study also challenges previous beliefs that Neanderthals lost genetic diversity at the start of their lineage. Fossils from Sima de los Huesos, an Atapuerca site, showed levels of variation similar to those of early Neanderthals from Krapina.
“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,” said Alessandro Urciuoli, lead author of the study.
“This challenges the common assumption of a bottleneck event at the origin of the Neanderthal lineage.”
