“Neanderthals are the best-documented pre-modern people in the fossil record in regards to morphology, genes, habits, and culture,” stated Dr. Alessandro Urciuoli from the Universitat Autònoma de Barcelona and coworkers.

“Recent molecular-clock-based analyses position their divergence– together with Denisovans– from the contemporary human family tree 765,000-550,000 years earlier, or older based upon morphological information.”

“The Neanderthal family tree distinguished quickly afterwards, as affirmed by the hereditary and morphological proof from the Middle Pleistocene Sima de los Huesos people, formerly thought about to represent Homo heidelbergensis and now considered an early population of the Neanderthal family tree.”

“While the hereditary divergence time is now well developed for the clade as an entire, dispute continues on the relationships in between European Middle Pleistocene populations, Middle and Late Pleistocene Neanderthal populations, in addition to the evolutionary procedures that resulted in the advancement of a complete ‘traditional Neanderthal’ morphology in late Neanderthals.”

“This is because of the mosaic morphology of the Middle Pleistocene specimens, the so-called muddle-in-the-Middle, from which Neanderthals are argued to have actually progressed.”

In the research study, the scientists determined the morphological variety in the structure of the inner ear accountable for our sense of balance– the semicircular canals.

They concentrated on 2 extraordinary collections of fossils: one from the Sima de los Huesos website in Spain, dated to 430,000 years of ages, which makes up the biggest sample of pre-Neanderthals readily available in the fossil record; and another from the 130,000- to 120,000-year-old website of Krapina in Croatia.

They determined the quantity of morphological variety (i.e., variation) of the semicircular canals of both samples, comparing them with each other and with a sample of traditional Neanderthals of various ages and geographical origins.

The findings expose that the morphological variety of the semicircular canals of traditional Neanderthals is plainly lower than that of pre-Neanderthals and early Neanderthals, which lines up with previous paleogenetic outcomes.

“By consisting of fossils from a broad geographical and temporal variety, we had the ability to catch a detailed image of Neanderthal advancement,” stated Dr. Mercedes Conde-Valverde, a scientist at the Universidad de Alcalá.

“The decrease in variety observed in between the Krapina sample and traditional Neanderthals is specifically striking and clear, supplying strong proof of a traffic jam occasion.”

“On the other hand, the outcomes challenge the formerly accepted concept that the origin of Neanderthals was related to a considerable loss of hereditary variety, triggering the requirement to propose brand-new descriptions for their origin.”

“We were shocked to discover that the pre-Neanderthals from the Sima de los Huesos displayed a level of morphological variety comparable to that of the early Neanderthals from Krapina,” Dr. Urciuoli stated.

“This challenges the typical presumption of a traffic jam occasion at the origin of the Neanderthal family tree.”

A paper on the findings was released in the journal Nature Communications

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A. Urciuoli et al2025. Semicircular canals clarified traffic jam occasions in the development of the Neanderthal clade. Nat Commun 16, 972; doi: 10.1038/ s41467-025-56155-8